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| Valve clearances and Camshafts | Rating: 
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| Posted: 12-31-2006 05:28 pm |
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1st Post |
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smcmanus Member 
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Both my camshafts are marked with MC25236 and 0351Y and A907E. Are these correct for this car? The valve clearances are: Intake from .002 to.005, and exhaust from .004 to .009 inches None of the valves are tight as I can turn the followers easily. How critical is this on the JH? Do I have to change out the shims? I'm afraid I know the answer, but await your guidance. It seems everything on this car was fiddled with and then put together again to maximize my frustration! It is one of those projects. Thanks and have a Happy New Year Steve
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| Posted: 12-31-2006 06:51 pm |
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2nd Post |
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Ron Mau Member
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Hi Steve, The shop manuel lists the clearances for the valves. Intake 0.005-0.007 Exhaust 0.010-0.012 Lokks like you'll be changing some shims. Ron Mau Davenport, IA
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| Posted: 01-01-2007 01:21 am |
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3rd Post |
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Mark Rosenbaum Member 
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Your cams are marked with the correct casting numbers, but that says nothing about the way the cam lobes are ground. Probably you have the stock JH cams unless there is a stamped number or machined groove present on the front part of either camshaft, just behind the timing gear. To give you an idea of what to look for, the attached photo shows a couple of type 107 cams, and you can see the 777.... stamped thereon. With the clearances you mention, I'd be hesitant about driving the car vigorously or for any considerable distance. While the intakes probably won't cause any immediate problems, the exhaust clearances are far too tight and I'd be very concerned about burning valves. I suggest checking your feeler gauges with a micrometer to make sure they're actually the thickness marked thereon. You may get lucky and discover that your gauges are too thick. Most likely, though, as Ron notes, you'll need to re-shim the engine. This is an expensive, tedious, and annoying process the first time through, as it is necessary to test-assemble each cam carrier to the head to ensure that its shims are in fact correct. If you record the shim thickness used at each valve, you can avoid most of that tedium the next time the job needs doing. Attachment: cams type 107 #1.jpg (Downloaded 127 times)
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| Posted: 01-01-2007 03:15 pm |
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4th Post |
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smcmanus Member
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I was hoping it was a JH tuner's secret to set the valves tight. I figured maybe the valve clearances increase as the engine warmed-up. Oh well. Can you measure your 107 cam from heel to lobe so I can check mine against it? As I mentioned, everything on this car has been monkeyed with. I'm wondering if someone modified it, or maybe just ground the valves when they did the head gasket. Thanks and have a happy New Year Steve
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| Posted: 01-01-2007 05:00 pm |
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5th Post |
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Mark Rosenbaum Member
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You can determine a cam's nominal lift by measuring the lobe height (the distance from the tip of the cam lobe to the belly of the base circle) and the diameter of the cam's base circle, then subtracting the latter from the former. By comparing your result to the likely alternatives you may be able to determine which cam grind you have. For example, I just made some not-very-accurate measurements on two lobes of a stock JH cam, as follows: Lobe A: lobe height 1.552", base circle 1.210", calculated lift 0.342". Lobe B: lobe height 1.550", base circle 1.205", calculated lift 0.345". For 907 engines, the various Lotus-developed cams are listed below. 0.340" - Type C or 101 cam, 907E0101G (stock JH). No special markings. 0.350" - Type D or 102 cam, 907E0102G. One groove at front of cam. 0.344" - Type E or 103 cam, 907E0103G. Two grooves at front of cam. 0.410" - Type 104 cam, 912E0104E. Marked 444..... 0.378" - Type 107 cam, 912E0107F. Marked 777..... In addition to the above, there are many aftermarket cams, mostly for racing of one sort or another: 0.416" - Delta Motorsports' current Type 104 variant 0.361" - Delta Motorsports' current Type 107 variant 0.420" - Dave Smith type DS2 0.420" - Dave Bean Type BLL-104 0.425" - Dave Bean Type BLL-105 0.375" - Dave Bean Type BLL-107 0.360" - Paeco Type JH-7000 Intake Only 0.420" - Paeco Type JH-7000 Exhaust Only 0.370" - Paeco Type JH-7800 Intake and Exhaust 0.415" - Paeco Type JH-8600 Intake and Exhaust Thanks go to Tim Engel, Garry Kemp, Kurt Housh, and Judson Manning for most of the data presented here. The photo in the previous posting came from somebody's eBay offering of quite some time ago, not from parts I have on hand. Attachment: cam measurements.jpg (Downloaded 676 times) Last edited on 01-01-2007 05:02 pm by Mark Rosenbaum |
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| Posted: 01-01-2007 05:55 pm |
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6th Post |
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smcmanus Member
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Mark WOW! Great information. Thanks Steve
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| Posted: 01-01-2007 10:55 pm |
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7th Post |
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smcmanus Member
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Mark I mic'd it out and came up with .350 for both the intake and exhaust. I guess that means I have the type D cams. Did it come that way from the factory? I don't know the history of this car. Happy New Year Steve
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| Posted: 01-02-2007 12:22 am |
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8th Post |
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Mark Rosenbaum Member
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I will again note that the measurements I posted earlier weren't all that accurate -- any or all of the readings I took could easily have been 0.005" or 0.010" off. Consequently, without proof to the contrary, I'd be inclined to think that your cams are actually Type C's. Regardless, unless your cams have the groove at the front, they're not real Type D's. It's my understanding that as far as anyone has ever been able to document, all JHs came from the factory with Type C cams. I will note that there's a long-standing rumor that a very few Home Market (UK) cars built early in 1974 had the same Type D cams used in Lotus cars that year, due to an alleged shipping error by Lotus that no one caught until after the cars were sold. I've never come across any actual proof that this might be true. However, I do think it's conceivable that Lotus would have deliberately made such an 'error', regardless of contractual obligations to Jensen, if it would have saved them a few bucks in manufacturing costs through not having to custom build a few engines. In those days, it was often said that when dealing with Colin Chapman, one was always very well advised to count their fingers and their pocket change after shaking hands with the man. It is also possible that a previous owner installed reground cams at some point in the car's history. A significant decrease in base circle diameter would be a very good indication of this. If so, then without some sort of documentation, all you can do is to measure lift versus rotation at many points and compare that information against similar data from possible candidates. That would be a challenging task.
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| Posted: 01-05-2007 06:55 pm |
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9th Post |
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smcmanus Member
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OK, I pulled the intake cam housing after carefully double checking the valve lash. I find there is a gasket so I called Delta to ask how thick their gaskets are and they told me 15 thousands. I mic mine and get about 10. So I guess maybe it crushed to about 10 when installed. The guy at Delta says I should use gaskets between the cam housing and the head and that it is a bad idea to eliminate the gaskets as the service manual recommends. Use the gasket or not? If the gasket maintained .015 thickness, my valves would be close to tolerance. I suspect the gasket will crush somewhat. What is the truth? If I dry assemble without the gasket I will have no clearance at all so it is pretty hard to accurately measure what size shims I need. What to do? Sorry to be such a moron! Thanks Steve
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| Posted: 01-05-2007 09:18 pm |
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10th Post |
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Greg Fletcher Administrator 
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Why would you use the paper gaskets? The gasket was a design flaw from the start. There was Lotus Service Bulletin way back when that clearly states paper gaskets under cam towers will leak (they always do) and to avoid that type of installation. You will never get away from the leaking at this spot if you don't correct it. It's really worth switching over in my opinion if you need to change any of the shims. You must change all the shilms at this point, but if you need to change half of them anyway, it's not like you're saving a lot. I've used Loctite 515 for many years and it has always worked perfectly. It provides a near zero gap and seals from oil leakage as long as it is needed. You can assemble everything dry for a final check and know that you will end up with the same clearance when done. I think shimming the valves is enough trouble without having to figure in additional measurements (which are always approximate).
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| Posted: 01-05-2007 10:33 pm |
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11th Post |
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smcmanus Member
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I just came in from dorking around with it. I dry assembled the exhaust cam after removing the gaskets and cleaning it. Two of the valves, which previously had .008 clearance, now have nil, but I can turn the lifters. The one valve which was had .009 has slight clearance, less than 2. Those with less than 8 were tight. So I guess it is about 8 thousands difference with no gasket. Anyone have a shim assortment they can loan me for a couple days? I'll pay shipping both ways and, of course, pay for the shims I use. Why use paper gaskets? That's why I asked! The guy at Delta said to use the gaskets but the JH service manual says don't. Thanks Steve
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| Posted: 01-05-2007 11:07 pm |
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12th Post |
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Mark Kleimola Member
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I too am in the process of installing cams and shimming the valves. Since I have switched over from the old base cams to the 107 cams I had, I find I need mostly all new shims. The new shims I need range from ~.100-.110 (exhaust) to about ~0.110-0.125 (inlet) based on my dry assembly without shims. Are these sizes readily available? All the shims in my possession range from 0.070 to about 0.095. Also if by chance someone has some thick ones they would swap for some thin ones 3 thin for 2 thick, or even want to sell, I'm open. Let me know at mkleimol@comcast.net.. Thanks Mark K
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| Posted: 01-06-2007 12:30 am |
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13th Post |
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smcmanus Member
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Let's trade!!!! I'll bring in the list of shims I've got and let you know. Steve
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| Posted: 01-06-2007 02:29 am |
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14th Post |
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Jensen Healey Super Moderator 
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I've found setting the valves a very frustrating process. The clearances seem to change randomly each time the cam carrier is bolted on. I think it may be related to worn valve stems and used shims. When the correct clearances are obtained the carrier needs to be removed one last time to apply the Locktite 515. That's usually when the shims fall out on the garage floor. Remember to shove a rag in the oil return hole so the nuts and washers don't fall into the oil pan. Kurt
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| Posted: 01-06-2007 02:42 am |
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15th Post |
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jcdean Member
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http://www.jensenhealey.com/forums/view_topic.php?id=425&forum_id=2 Just to remind those who already know and inform the newer members, the shims from the 8 valve SAAB 900 up to 1987 IIRC are a perfect fit. They come in metric sizes and I have ordered them on the internet and purchased them from the local SAAB mechanic. They are a bit cheaper than the Lotus items. Kurt Copied this from a previous post by Jensen Healey, aka Kurt. The entire post is worth reading. Joey Last edited on 01-06-2007 02:45 am by jcdean |
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| Posted: 01-06-2007 03:21 am |
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16th Post |
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Jensen Healey Super Moderator
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Update: SAAB shims are now more expensive than the shims available at the club store. Don't believe everything you read! Kurt
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| Posted: 01-06-2007 05:02 pm |
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17th Post |
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smcmanus Member
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How about this? I mentioned in a different thread that when I took off the exhaust side cam cover about a quart of oil dumped out. I didn't get any feedback so I assumed that it was normal. Maybe not! The exhaust cam case has the rear oil drain hole blocked with what appears to be epoxy. What the....? In the picture the exhaust cam is closest to the camera and the arrow points at the blob blocking the drain hole. I scratched it and it is non mettalic; maybe BJ weld or something. Am I right in thinking this needs to be removed? Thanks Steve Attachment: jhcamoilhole.jpg (Downloaded 86 times)
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| Posted: 01-06-2007 11:33 pm |
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18th Post |
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normv Member 
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Steve I know one of my engine's which was rebuilt under the original warranty in Australia has a Plastic plug in this location and another earlier engine I have doesn't so mabey it was a warranty addition or appeared on later cars as the one which has it to have a proper shaped plastic fitting glued in Looks like it is meant to be there. Many engine use the engine oil to cool the valve springs and stems particularly on the exhaust side so I suggest this is to flood the area with oil for cooling. Norm
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| Posted: 01-07-2007 03:28 am |
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19th Post |
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smcmanus Member
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The goop in the drain hole keeps the oil around the cam (and leaking out of the cover) but does not keep the valve stems or springs in an oil bath. The drain holes in question are in the cam case, not in the head. This does not look like something the folks at Lotus would do. This car has a nice protective coating of oil and was leaking like a sieve. I wonder if pluggung this hole was an attempt to stem the flow of oil from between the cam case and the head? There were also ample amounts of blue silicon sealer smeared all over. Have a nice day Steve
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| Posted: 03-13-2007 01:17 am |
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20th Post |
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Dan Eiland Member
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As a lot of you know I am rebuilding my engine and upgrading at the same time. Today I switched over to the newer style cam carriers which required that I remove ten of the mounting studs which are replaced by star headed bolts. I moved my new cams from my old carriers to the new ones and checked to make sure they were indeed the Delta 104 cams. The base measured 1.065 inches and the lobe height measured 1.481 inches. If I subtract the base for the lobe height I get 0.416 inch lift which corresponds to all the data I have as well as what Mark has already posted. Of course I did find on the end of each cam that they had been stamped with "DELTA 104", so now I know I have the 104 cams with 0.416 lift. I'm now wondering what the clearance should be between the follower and the base of each cam lobe? Should it remain the same as what the book says or does it change with the 104 cams. If it matters I'm also converting to the 2.2L crank. Any assistance would be appreciated.
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| Posted: 03-14-2007 10:42 pm |
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21st Post |
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DeDub Member 
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I'm setting my valves for the 1st time and am looking for a supply of shims to play with. Most of the ones I need I don't have because the PO, like so many others, it sounds, used gaskets under the cam towers. Between that and most of my clearances being too small already, I need all new shims and I'm not even sure exactly which ones. So buying a few dozen that I may not use is a bit daunting financially. Anyone have a personal supply they want to share. I'm glad to pay for the favor. David
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| Posted: 03-14-2007 11:49 pm |
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22nd Post |
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smcmanus Member
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List what shims you need and maybe someone can help. I have some I can't use. Also, Delta has them at a reasonable cost. Have a nice day Steve
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| Posted: 03-15-2007 06:22 pm |
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23rd Post |
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DeDub Member
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I am tentatively looking for the following cam bucket shims, in thousandhts: 60 X 2 64 X 2 65 X 2 67 X 2 69 72 73 81 95 and undoubtedly several others around these numbers, as I removed the existing gaskets under the cam towers and shrunk the clearances to the point that I can't measure them any more with my existing shims. If I was sure of exactly what I needed, I'd just buy them from the company store, but I'm only guessing here and would love to find someone with a selection I can play with. TIA, David
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| Posted: 03-15-2007 07:08 pm |
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24th Post |
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Greg Fletcher Administrator
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Hmmm, that is a bit of a problem. Ideally, you would get your trusty machine shop doing your vavle job to check the length of the valve stems and, being the great guys that they are, they would grind them to the exact length to put you in an ideal shim range, between .070 and .080". In reality, most shops don't care and don't check this which is why you need to tell them ahead of time (or better yet use a great shop like West Coast Cylinder Head). If you have no clearance now for a gauge, you'll need to do some careful filing of the stem. Probably best to take it back and it have done right to insure the material removed is all at right angles to the base. I do have a box of used shims I can loan you, not sure if all the sizes are there, send me an email on that. BTW, the JHPS 104 cams are 0.432" lift and 268 degrees duration but with 235 degrees duration at 0.040" lash. These will give slightly better torque than most of the profiles out there.
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| Posted: 03-16-2007 06:43 am |
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25th Post |
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Dan Eiland Member
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I just came in from the garage where I have been measuring all the shims just to make sure what thickness they are before I reinstalled my cam carriers. With my cam carriers torqued down, I began measuring some of the clearances. I have the Delta 104 cams and I have no idea who did the valve job, but there is a lot of space that has to be made up. So far I have only looked at four of the intake valves from the first two cylinders. If I set my clearance at 0.007 I would need oversize shims on all my valves from the measurements I'm currently getting. Starting from the front of the engine here is my list of shims I would need to have .007 clearance on the first four intake valves: one - 0.145" shim; one - 0.139" shim; and two - 0.142" shims. I hope they make shims in these sizes or I'm going to have to buy all new valves even though mine are brand new.
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| Posted: 03-16-2007 12:32 pm |
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26th Post |
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smcmanus Member
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Ouch! The parts book says shims are available from .060 to .130 of an inch. This creates a situation for which I know not the answer. The cams you have are probably regrinds which took off a lot of metal to get the desired profile. Maybe someone has some over-sized shims or some uncut cams available. My problem was the opposite. I have the stock(?) cams and removed the gaskets when I fiddled with the valves. I needed smaller shims but was fortunately they were available. Good Luck Steve
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| Posted: 03-16-2007 04:17 pm |
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27th Post |
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Jensen Healey Super Moderator
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Dan, remove the gaskets and give them to Steve. ;-) Dedub, I have 86 shims if you want to borrow them. Just bring along your first born as a deposit for their safe return. Send me a message. Kurt San Anselmo Last edited on 03-16-2007 05:16 pm by Jensen Healey |
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| Posted: 03-16-2007 04:21 pm |
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28th Post |
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DeDub Member
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I've got a set I just took off, too. How many will you need to stack up to get within shim range? 8)
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| Posted: 03-16-2007 04:59 pm |
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29th Post |
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Greg Fletcher Administrator
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This topic comes up fairly often. Although not recommended, shims do come up to .150" and owners have used them without problems from what I've heard. I have also heard of owners getting customs shims made by a machinist in even larger sizes. Alternately, it is possible to machine the cam towers about .060" or so to get into a smaller shim range. This has been done many times in the past without any issues I know about, and certainly has something to be said as a solution. Keep in mind that technically you are changing the cam center line angles, even it's ever so slightly, so my first inclination would be to fix the head by getting oversized valves to start with. Then again used JH cam towers are pretty common and it should be easy to fix at a later date when it needs to be done again.
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| Posted: 03-16-2007 06:08 pm |
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30th Post |
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Dan Eiland Member
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Greg, good suggestion on having my cam towers shaved to get into some more common shim sizes. This would be simple enough and not too costly. At a later date if I needed a valve job again could'nt I just have the valve stem heights adjusted to fit? Seems cheaper than purchasing new towers, especially when you have the newer style Lotus cam towers.
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| Posted: 03-16-2007 06:23 pm |
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31st Post |
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Greg Fletcher Administrator
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Changing the engine geometery is not an ideal fix, but it's certainly a cheap fix considering the alternatives.
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| Posted: 03-16-2007 07:47 pm |
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32nd Post |
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Dan Eiland Member
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I haven't checked, but could the newer cam towers be taller than my old ones?
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| Posted: 03-16-2007 09:07 pm |
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33rd Post |
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smcmanus Member
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If the head is coming off, you could grind the valve seats to drop the valves a little and tighten up your clearances. If you are leaving the head in place, I think the thick shims are the best solution. Good Luck Steve
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| Posted: 03-17-2007 03:18 am |
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34th Post |
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LambandAndy Member 
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David, I removed my gaskets and had a machinist buddy surface grind 8 shims down to 0.060" (minimum recommended) that I used to figure out what I needed to order. Note: DO NOT surface grind shims to run in the engine. I believe that they are case hardened and you will grind off the hardening (Someone correct me if I am wrong). I still have them and if you e-mail me (limey01@aol.com) your mailing address would gladly send them to you (or anyone else that could use them). Andy 15223
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| Posted: 03-17-2007 05:05 am |
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35th Post |
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Dan Eiland Member
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Greg please do something about the way the message board wipes things out when you go to retrieve a photo or if the photo size is too large and you go to fix it and come back and your entire message is gone. There is no telling how many great posts have been dropped because one does not want to type it 10 times because it gets wiped out everytime something comes up. I went to look at a photo I was going to share with some great information I found out today and my entire message was gone when I came back to the message board. I retyped the message only to have it wiped out again when the photo exceeded the boards size limit. Not worth the bother.
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| Posted: 03-17-2007 08:07 am |
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36th Post |
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Jensen Healey Super Moderator
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I learned to do a right click copy so I can paste it back in if it gets lost.
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| Posted: 03-17-2007 06:34 pm |
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37th Post |
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Dan Eiland Member
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Since my 104 cams came from Delta Motorsports I called and spoke with Jim Medland yesterday about my camshaft/valve clearance issues and he fixed me right up. He explained that the oversized shims are required on most reprofiled cams so he had just what I needed in stock. I ended up replacing all 16 shims with 10 differnet sizes ranging from 0.141 to 0.158. I think I wiped him out of some of the sizes I needed. I should have the new shims by Monday or Tuesday so I can finish up my engine. I have to admit that the shims take a lot of time to get right. I need to thank everyone for their advice and thoughts on the subject. I took Mark's advice and went back and measured every shim I had and it turned out that some were no longer the same size as the label had indicated. I used my Digital Micrometer (DM) and my Dial Caliper (DC) to check every shim. This ensured I double checked every measurement and it helped me round off the sizes to the nearest 1000ths since the DM goes to 5/10000ths accuracy. I recorder every measurement and labled every valve so I will know where all the shims go when they get here. Now I will have to tackle rebuilding my Dellorto carburetors next. Have attached a photo of the engine partly back together. I'll send another when it is done. Just a note that you can see in the photo where I enlarged the water opening in the block from the pump through the block into the area surrounding all the liners. I also added the port to the rear of the head for better water circulation. Attachment: 2.2L going back together.jpg (Downloaded 92 times) Last edited on 03-17-2007 06:39 pm by Dan Eiland |
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| Posted: 03-21-2007 06:48 am |
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38th Post |
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Dan Eiland Member
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Just an update- My shims came in tonite so hopefully I'll be able to install them tomorrow.
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| Posted: 03-22-2007 07:31 am |
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39th Post |
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Dan Eiland Member
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How critical is it that the clearances be exactly according to the book? My measurements must have been off by a thousandths or two due to stacking feeler guages to take measurements. I was going for the high side of the stated clearances (.007 In; .012 Ex) and now I have a bunch that are off by .001 to .003. Should I just bite the bullit and re-order to correct this. The shims are cheap enough so the cost is not an issue. Also, should I make sure all the In valves are set at 007 and all the ex at 012 or it really does not matter as long as they are between the set specs? I have heard that the valve clearances tighten up over time. How true is this? Thanks for everyones input.
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| Posted: 03-22-2007 04:48 pm |
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40th Post |
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Greg Fletcher Administrator
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Your clearance will tighten over time, always best to be on the high side. In the dealer days, I've heard that mechanics would often shim the exhausts as much as 0.014" to keep everything within range over a longer time. I always shoot for 0.012 on the exhausts.
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| Posted: 03-22-2007 05:37 pm |
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41st Post |
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Jensen Healey Super Moderator
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Dan, if you remove the cam tower, rotate the shims and re-install it you will find the measurements may change. Adjusting valve clearances on the 907 is a black art. You will not want to do this again soon, so order the shims and shoot for the high side. Throw away any shims that have obvious indentations from wear. They may not seat correctly and clearances could change within a few miles of driving. When you get them all within range, goop the towers with Loctite 515 and watch all your measurements change again. I made 6 or 7 attempts before settling on "good enough". May the Lords Of Lucas be with you, Kurt
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| Posted: 03-23-2007 06:02 am |
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42nd Post |
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Dan Eiland Member
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Kurt, I placed a thin layer of Loctite 515 on the towers and then torqued them down and measured all my clearances. I then removed the towers and cleaned all the loctite from the parts and then re-installed the towers, torqued them down and measured all my clearances again. For what it is worth, there was no measureable difference. I admit I used my finger to spread the 515 and I admit I spread a very thin layer. I did not measure the thickness of the 515 that I removed but my guess----less than or equal to 0.0005". With this issue aside I made a list of all my clearances and all my shim sizes and then found all the sizes I would need to bring all the clearances into spec on the high end. I called Jim at DMS and placed my order this morning. In the mean time I went by our local speed shop and purchased a Ford style remote oil filter kit. Installed the engine part of the kit as soon as I got home from work. My parts from Dave Bean also arrived today ( just some special washers and gaskets for my Turbo Esprit cam housings). They also got installed when I got home from work. My engine is getting closer to being finished everyday. Of course every day I feel further and further from finished.
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| Posted: 03-23-2007 03:40 pm |
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43rd Post |
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DeDub Member
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OK, being my first time at the "black art" of Lotus cam shims, it's obvious to me there's a fair amount I don't understand: I'm shimming an unknown, used, new-to-me motor I'm thrown in my fresh body. I've started it, it ran fine and didn't smoke, but because it may be in there for a year or two I thought I'd better check valve adjustment. It needed it; most exhausts were in the single high digit range. And there were gaskets under the towers. So I made some guesses, ordered up a bunch of shims in the 60s range and started the tedious process of learning how fast I can install and remove the exhaust tower. I'm not known for my small, delicate hands. All was going OK except for the last valve on the back of #4 which continued to have zero clearance no matter how small a shim I had in there. Finally I put in the tower with NO shim there and tried to measure that way but couldn't get 50 thou of stacked feeler gauges to bend enough to get a satisfactory measurement but it seemed to be in the high 40 range with no shim at all. I'm kinda stuck. The part that's got me in a mental whirlwind is that I remember, and my notes show, that I got a 9 thou feeler gauge in there the first time I checked them, before I ever took the tower off the first time, and when there was still a gasket under there. How could this be? I can't imagine anything I could have done that would have *raised* the valve stem and shrunk the clearance at least 20 thou. Visually, the stem does look higher than the adjacent and with the tower in, the bucked looks to be about 20 thou or so higher than the adjacent. FYI, none of the valve stem heights are very similar; obviously the PO didn't have a quality valve job done at some point. I don't want to pull the head for one lousy high valve on an engine I don't plan to have in there forever but even a 60 shim doesn't seem to have any clearance. Any ideas?
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| Posted: 03-23-2007 06:33 pm |
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44th Post |
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Jim Sohl Member
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David, Well... some warning signs seem to be present. If, as you say, the stem is visually higher than the others, then something has allowed that valve to recede into the seat. You state that the engine 'ran fine'. A compression check might suggest otherwise, or better still, a leak-down test. It will be very important to follow up on your wayward valve for several reasons: 1) valve trouble is always important; 2) 907's are difficult to work on (you know that first-hand) and owners (of course I mean po's) often neglect proper valve care; 3) 907's have a history of 'burning' exhaust valves; and 4) numbers one, two, and three sound like your engine. 'Sounds like off-with-the-head to me. Conceivably, some weird coincidence of warped castings could produce your symptoms, but I doubt it given that receding exhaust valves are relatively common in 907's and most 9xx Lotus engines for that matter. My advice then is double check and triple check the symptoms to try and find a cause that may suggest that a burned valve is not the problem. If you do have to remove the head, check the stem to guide clearance on all valves. If the valves wiggle around more than a few thousandths (with the springs off), it is highly indicative that a general overhaul is in your future. Also, assuming you do have a burned valve, the seat may be too far gone to rehabilitate. This will require close examination for the reason that 907 seats don't grow on trees. Try the usual suspects, DMS, Dave Bean, etc. Hopefully, you will be able to get things right without removing the head, but obviously, don't trust to luck with an engine that is expensive/difficult to repair even when the 'normal' repairs are indicated. It is my belief that a 907 properly used means high output at high RPM, things that stress valves and pretty much everything else more than your average street engine. Good luck! Jim. p.s. I have '73, '74' & '79 907's and an '84 910. All are high mileage and all have valve issues of one sort or another.
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| Posted: 03-24-2007 06:34 am |
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45th Post |
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DeDub Member
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Thanks for the response, Jim. I have 3 heads and I think I'll pull my two spares and look them over carefully as replacements. It's obviously a lot easier to set the valves with the head on the bench anyway. I'm flummoxed by the last valve and much as I want to button this puppy up, I can't so I guess I'll be learning about Lotus heads sooner than I expected to. Those exhaust nuts looks so damn fiddly and the intake's not much better. Oh, well, eh? David
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| Posted: 03-29-2007 05:43 am |
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46th Post |
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Dan Eiland Member
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Here is my progress report on shimming the valves on my engine rebuild. I now have all the exhaust clearances set at 0.012 and they went fairly easily. The intake valves are a whole different story. I can take the cam carrier off and put it back on without changing a thing and I get totally different measurements on some of the valves. I received a second order of shims from Jim at DMS and they should have set the clearances dead on to the specs on the high end but that did not happen. I have played around with the shims until I finally got all the exhaust clearances at 0.012 and stopped there for the day. The next day I went back and started working on the intake valves to see if I could get them to come into spec. No such luck. At this time I had all set to either .007 or .006 with the exception of two. I figured I would need to order two more shims and that would work. Well, I went out to the garage to check the intake clearances again and now one valve that was at .007 is at 0. All I can think is something got in the last time I removed the cam carrier. I've stopped for the evening and will call Jim tomorrow to order a few more shims to play with (sizes I don't have or I need extras of). This has been challenging to say the least and frustrating to no end, but a good learning experience. I know I'm very close to getting these clearance set just right, but then how do you make sure they stay at the same clearance when you go to mount the cam carriers for the last time? Last edited on 03-30-2007 12:43 am by Dan Eiland |
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| Posted: 03-29-2007 06:37 am |
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47th Post |
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Dan Eiland Member
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After writing my last reply it hit me that one of the shims probably slipped out of place causing the clearance on one of the valves to go to zero. I ran out to the garage and removed the cam carrier and I was right. I put it back in place and everything is either .006 or .007 with the exception of two valves. I'll order new shims for the two valves that are still out of spec and that should take care of setting the valve clearances.
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| Posted: 03-29-2007 08:03 am |
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48th Post |
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DeDub Member
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What a pain, eh, Dan. I'm in exactly the same place. Just finally, after the better part of a day today, got the exhaust to all within one thou of 12. Good enough for me, but I ran out of shims for the intakes so I'm waiting on shims, too. IYR, I was having trouble with a few of my exhausts needing shims less than 60, one quite a bit less. I was about to pull the head when on a whim I pulled the towers off another parts engine I had and voila! there were a pair of reground 107s. So now all the shims I need are around 100 instead of 60s. Much better, and hopefully the 107s will the torque a help a bit on this bone stock motor. But as so many JHers have undoubtedly found out before me, this is not a job I want to do very often, at least in the car. David
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| Posted: 03-29-2007 09:03 pm |
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49th Post |
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Jensen Healey Super Moderator
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Hi David, Precisely why my 107 cams are sitting on the bench. I hesitate to even remove the cam covers that don't leak. You are very lucky to find the performance cams. If they are regrinds of stock cams they should work well enough with the stock 110^ pulleys even though Lotus used 104^. The true Lotus 107 cams have the keyways offset so don't mix and match JH parts with them until you have done your research. Hope to see you on the road soon. http://www.nobbc.com Kurt San Anselmo
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| Posted: 03-30-2007 12:52 am |
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50th Post |
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Dan Eiland Member
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Yes David, this is a pain. It can make a sane person go insane. I have one valve with a shim that is 0.152 and has a clearance of 0.008. I do not have a shim that is 0.153 to close the gap so I do have a shim that is 0.154. This should bring the clearance into spec at 0.006. I install the 0.154 shim and my clearance is now 0.004. You tell me how that happened? Yes I checked the thickness of the shim. It is correct with a few ten thousandths. More shims on there way. I'm determined to get this right. Last edited on 03-30-2007 12:53 am by Dan Eiland |
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| Posted: 03-30-2007 04:49 am |
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51st Post |
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DeDub Member
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Kurt, Your mention of using 110 pulleys for my 107 cams made me realize I didn't understand the subtle dynamics of all the cam timing threads I read on the different forums here. 104^ was talked about for the 107 cams and even a 100^, which is a long way from 110^. But my question is: why can't I use my stock pulleys that are both marked at 110 and 115^, but just line them up where 104^ would be? Any one reading this thread who has an opinion on this? David, only needing a windshield, air cleaner, and paint to put his JH on the road.
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| Posted: 03-30-2007 05:09 pm |
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52nd Post |
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Greg Fletcher Administrator
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You can do that, but to get it spot on, you would need the later style adjustable pulleys- converting means changing all pulleys and using the uprated half-moon timing belt. It's all good, but expensive. The stock pulleys on the Jensen Healey are only keyed for one setting.
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| Posted: 03-30-2007 05:22 pm |
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53rd Post |
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Jensen Healey Super Moderator
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Hi David, You will find it difficult to adjust the pulleys except in whole tooth increments. The factory moved the keyway on the pulley to create the various degrees. Notice that the 110in and 115in are on opposite sides of the pulley. Each tooth of the 40 tooth pulley is 9^, but since the cams turn at half the speed of the crank, it represents 18^ of cam timing which is measured at the crank. The difference between 110 and 115 is less than 1/3 of a tooth. The simple answer is you have two options: use the 110 pulleys if you have reground early JH cams (A907E0351Y) or purchase adjustable pulleys and time them properly to 104^. For a full explanation of cam timing madness read this: http://www.jensenhealey.com/forums/view_topic.php?id=353&forum_id=2&highlight=turbo You didn't really want to know all of this stuff, did you? Kurt Last edited on 03-30-2007 07:58 pm by Jensen Healey |
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| Posted: 04-01-2007 01:18 am |
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54th Post |
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DeDub Member
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Yes, I do indeed have early regrinds: 907E0351Y, but ground till there's about .378 lift, which makes them appear to be Dave Bean regrinds. They're in fine shape; no visible wear. BUT reading that short PhD thesis (at least it looks like it with MY level of understanding) leaves me a bit concerned, as my cams are definitely JH, but the pulleys that were attached have a raised "LOTUS" in between two of the 6 holes in the web. But there's no sign of paint dots and yet there are 110 & 115 marked in the web with corresponding little slash marks on the rim. From my reading, the word 'lotus' on the web makes them sound like incorrect lotus pulleys but the other markings make them sound like JH pulleys. Yes, I'm confused. Another point is to use two solid web magnesium looking pulleys that were on one of my motors, which are also marked 110 & 115 but no other markings. Anyone willing to chime in with some advice before I button it up? I am deeply appreciative of the generosity this Club already. It's hard to imagine getting a dead JH running without this help. Thanks, David
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| Posted: 04-01-2007 01:44 am |
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55th Post |
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Jensen Healey Super Moderator
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You have the correct pulleys. The 110/ 115 pulleys were never used on Lotus cars.
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| Posted: 04-01-2007 04:44 am |
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56th Post |
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Greg Fletcher Administrator
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Jensen Healey wrote:The true Lotus 107 cams have the keyways offset so don't mix and match JH parts with them until you have done your research. I don't think that's correct. I have an original 107 cam and an original Federal C cam side by side and those are both keyed identically. You would need adjustable pulleys to make any difference on those.
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| Posted: 04-02-2007 04:40 pm |
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57th Post |
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Jensen Healey Super Moderator
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Hi Greg, I went to the garage to inspect several cams after your post. I was unable to see any offset when comparing the Lotus 107 to a JH regrind. The article in question states a 7 1/2^ offset which translates to 3 3/4^ on the cam pulley. This is about 100th of 360^ and I visualized an analog clock where this would be 36 seconds of movement on the minute hand. Not a easily detectable amount without accurate measuring tools. I may take the cams to the machine shop later this week to have these things measured and put this issue to bed. Kurt
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| Posted: 04-02-2007 05:02 pm |
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58th Post |
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Greg Fletcher Administrator
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I was eye balling it with a metal straight edge, not super accurate I know, but I was trying to see any minute difference. The tops of the lobes and the oil holes all seem to line up with the key ways. A large degree wheel would answer this question, I'll see if I can find one.
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| Posted: 04-03-2007 04:41 am |
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59th Post |
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Jensen Healey Super Moderator
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I tried the same thing and the straight edge seemed to line up off center on the keyway with both cams.
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| Posted: 04-14-2007 04:17 pm |
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60th Post |
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Jensen Healey Super Moderator
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After a clarification by a member of a Lotus forum, I do believe there must be a slight keyway shift from the old JH cam and the later JH and Lotus cams. How else could the later pulleys achieve a 10 degree change in timing when flipped over vs the 5 degree change of the older JH pulleys? I would still recommend avoiding mixing early and late cams and pulleys. Kurt
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| Posted: 01-27-2010 03:06 am |
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61st Post |
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roverman Member
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Hi, Maybe under the, dumb question category, has anyone considered use of, or plagerizing the design of," Vega "buckets? No shims, just a "tapered" adjusment screw. Yes, they make some noise because adjustment is only to .002",(half turn of adjustment screw).I won't even mention hyd. buckets-oops! roverman.
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| Posted: 06-16-2019 04:10 pm |
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62nd Post |
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Dakota123 Member
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Greg Fletcher wrote:. Snip... That’s interesting, Greg— It’s been a long while since I started on my 2.2L build, and I was sorting through the cams I have on hand. One of them has three grooves (which may or may not mean anything, I know), a wide nose rather than the sharper nose of the two 104s I have on hand, and ~0.430” lift. Does this sound like the club store 107, maybe?
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| Posted: 06-19-2019 03:22 pm |
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63rd Post |
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Dakota123 Member
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Or, if not Greg, anyone? The relatively high lift has me confused as to what cam that might be.
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| Posted: 06-20-2019 05:31 pm |
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64th Post |
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Greg Fletcher Administrator
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I don't know what 3 grooves could mean on a camshaft. 2 grooves would be a "E" camshaft from Lotus. On the 104 cams from the club store, those have .428 lift, no markings. The 107 would have a .387 lift. I believe a 104 cam originally from Lotus would be marked on the nose with a "444".
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| Posted: 06-21-2019 02:34 am |
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65th Post |
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Esprit2 Member
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LOTUS Cam ID . . . C . . . . . . D . . . . . . E . . . . . . . . 107 . . . . . 104 Marking . . . . . . . . None . . . 1 Groove . 2 Grooves . . 7777 . . . . 4444 Lotus Lift (inch). . . 0.340" . . 0.350". . . 0.344". . . . . 0.378" . . . 0.420" JHPS Lift . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.387" . . . 0.428" (what else is different ?) Delta Motorsports'. . . . . . . . . . . . . . . . . . . . . . . . . . 0.361" . . . 0.416" (what else is different ?) Int. Opens, BTDC . 26°. . . . . 25° . . . . . 27.5° . . . . . 22° . . . . . 32° Int. Closes, ABDC . 66°. . . . . 65° . . . . . 52.5° . . . . . 50° . . . . . 60° Exh Opens BBDC. . 66°. . . . . 65° . . . . . 52.5° . . . . . 50° . . . . . 60° Exh Closes ATDC. . 26°. . . . . 25° . . . . . 27.5° . . . . . 22° . . . . . 32° Overlap . . . . . . . . 52°. . . . . 50° . . . . . 55°. . . . . . . 44° . . . . . 64° Duration. . . . . . . . 272°. . . . 270° . . . . 260°. . . . . . 252°. . . . . 272° Besides lift, what else about the JHPS & Delta versions of the 104 & 107 cams is different from the Lotus versions? Lotus coined all the original cam names. For JHPS, Delta, or any other cam grinder to use the same names without clearly noting any differences only adds confusion. That's not a 'service'. Regards, Tim Engel Last edited on 02-01-2020 11:05 pm by Esprit2 |
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| Posted: 06-21-2019 03:56 pm |
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66th Post |
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Dakota123 Member
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Weird... well, one groove looks a bit different than the other two now that I look more closely, so I’m betting it started life as an E. Think I’ll get a degree wheel and try and figure out what it is.
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| Posted: 06-21-2019 05:29 pm |
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67th Post |
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Esprit2 Member
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Dakota123 wrote:Weird... well, one groove looks a bit different than the other two now that I look more closely, so I’m betting it started life as an E. Think I’ll get a degree wheel and try and figure out what it is.Years ago, I bought a 907 cam carrier on eBay. It came with a cam installed that had none of the usual Lotus ID marks, but it did have "Delta" stamped on the back end. I called Delta Motorsports and they said it wasn't one of theirs. So I called Delta Cams, and they also said it wasn't one of theirs. :-/ I used a degree wheel to map it's lift profile, and it's a wild, long-duration cam, clearly not for street use. It's not a Lotus cam, and I've never found any cam spec that matches it. It's unfortunate that aftermarket cam grinders weren't more diligent about marking their products, and/or obliterating any original marks that might be confusing down the road. And it's unfortunate that, as a group, they weren't more respectful of existing Lotus cam names. If you don't know the source (ie, from Lotus), "104" and "107" have become as meaningless as "3/4 Race". 'Back in the day', every cam grinder made a "3/4 Race" cam for your small block V8, and they were all different. I would have preferred to have the true meaning of "104" and "107" preserved, but what you get now depends upon where you buy them. Besides frustrating my 'OCD', it makes email-helping someone de-bug their cam timing problems very difficult, since you really don't know what they have. FYI... Other LOTUS cams. Competition only, not used for street applications, and no longer available from Lotus. Cam . . Part Number . . ID Mark . . Lift (inch) . . Duration . . . MOP . . . . Comments 105 . . . A908E0105 . . . 105 . . . . . 0.433 . . . . . 296 . . . . Per event . . Sunbeam-Talbot Rally Engine 106 . . . A908E0106 . . . 106 . . . . . 0.450 . . . . . 320 . . . . Per event . . Motorsport Cam 108 . . . A908E0108 . . . 108 . . . . . 0.460 . . . . . 304 . . . . Per event . . Motorsport Cam Regards, Tim Engel Last edited on 06-21-2019 05:31 pm by Esprit2 |
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| Posted: 06-21-2019 06:15 pm |
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68th Post |
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Esprit2 Member
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Greg Fletcher wrote:I believe a 104 cam originally from Lotus would be marked on the nose with a "444".Correct. Lotus Markings are on the exposed bit of cam that's visible between the pulley and the cam carrier: In Lotus' early part numbering system, all cams had the same part number, but with a letter prefix to identify each cam. The C, D & E cams were from that era. The A & B cams were 'developmental' cams from before the 907 went into production, and were never sold. At some time between the E-Cam and 104-Cam, Lotus changed their part numbering format. Each cam got it's own part number, and the cam's ID referred to the last three digits of it's part number. The early C, D & E cams were also issued new part numbers, but the old 'alpha' names stuck as 'street' names. Lotus Cam Names and Part Numbers. . . . . . . . . . . . . ID Mark on the Cam's exposed shank. C-Cam = C907E0351Z = 101-Cam = F907E0101G . . . None... a smooth shank. D-Cam = D907E0351Z = 102-Cam = G907E0102G. . . One groove cut all around the shank E-Cam = E907E0351Z = 103-Cam = J907E0103G. . . . Two grooves . . . . . . . . . . . . . . . . . . 104-Cam = A912E0104F. . . . 44444444... stamped all the way around the shank. Competition Only. . . . . . 105-Cam = A908E0105 . . . . 105 stamped in one place on the shank, not 'all around'. Competition Only. . . . . . 106-Cam = A908E0106 . . . . 106 in one place . . . . . . . . . . . . . . . . . . 107-Cam = A912E0107F . . . 77777777... all around. Competition Only. . . . . . 108-Cam = A908E0106 . . . . 108 in one place Regards, Tim Engel Last edited on 06-21-2019 06:22 pm by Esprit2 |
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| > Jensen Healey & Jensen GT Tech > Engine & Transmission > Valve clearances and Camshafts | Top |
