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| cams, valve timing and ignition timing | Rating: 
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| Posted: 04-03-2014 07:02 pm |
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21st Post |
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Barthol Member
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Hi Again, I think that I am getting closer to be a little wiser:-) Looking through the answer from "Subwoofer" I conclude the following: Inlet cam: MOP ( Max opening point) of 110 means that the maxvopening point occurs 110 deg. after TDC Exh.Cam: MOP of 110 means that the max opening point occurs 110 deg before TDC. Is this correctly understood? Then some more questions. Looking on my cam wheels they are reversible and marked ink and exh on both sids, on one side there is also a raised dot in the casting. Can anyone clarify wether this is 104 or 107 mapping? My cams are definitely C-cams with the low lift, I am building a 2,2 ltr engine with 45 mm dellortoes, and app 9,5:1 in CR. Can I with susses use these cams / cam wheels. or do I need to go for other options.( the car must be torquey and is only used in traffic,- no racing) Last question. When I measure the opening and closing angles of the valve, what clearance do I need between the Cam and the followers. Normal setting with cold engine or "0" clearance with cold engine?? I know it is a lot of questions , but any help will be highly appreciated as , I want to get the engine as r"Right" as possible the first time. Thanks lot. Kim
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| Posted: 04-04-2014 12:42 am |
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22nd Post |
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Art DeKneef Member
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Let me say I am as confused as you are and am trying to figure this out on one of my cars now. It sounds like your engine is from a 1974 car. I'll answer what I can. The C cam is the stock cam that was standard in all JHs. There is no 104 or 107 mapping with the C cam. The 104 and 107 refer to different grinds that Lotus used in different variations of the 907, 910 and 912. The pulleys are reversible. One side goes on the intake cam and the other side goes on the exhaust cam. Then you line up the marks accordingly. This gives you your cam timing. You are building a 2.2 L engine with Dell 45s and higher compression. Based on what I have read and understand, you will need to use either the 104 cams, 107 cams or the 104/107 combo to get the power I think you want out of the engine. Using the stock C cams will limit the engine. But with the 2.2 crank it may be torque enough for you. I don't recall anyone doing a stock 2.0 engine to a 2.2 that didn't change cams also. If there is hopefully they will chime in and share their experience. According to the shop manual there are 2 types of cam pulleys. The original (side 1: 110EX, 115IN - side 2: 115EX,110IN) type covers the years 1973 and 1974 up to engine 10480. After engine 10480 there is a new pulley (side 1: 110EX, 100IN - side 2: 115EX,110IN) that went on catalyst equipped cars. If I understand you correctly on the clearance between the cams and followers, the shop manual recommends valve clearance cold of 0.005-0.007in inlet and 0.010-0.012in exhaust.
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| Posted: 04-04-2014 05:02 pm |
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23rd Post |
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Barthol Member
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Hi, Just did some more measuring I measure the lift of the cams to be 9 mm app 0,359". The camshafts have no stampings but they have 2 groves in the front indicating E-cams?? ( I believe that the lift of the E cam should be around .340"?? looking on my cam wheels they are reversible with the txt EX and IN in raised text on both sides of the cam wheel. Additionally there is a raised dot on one side of the Cam wheel. Measuring clockwise from thee keyway to the in -marking I measure 162 deg and the same measurement to the ex mark is 198 deg. anyone who can clarify what exactly I have , and wether it would be the right choice for my project. The question I had about the valve clearance was only at which clearance I should use when determening the opening and closing degrees . have a nice weekend kim
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| Posted: 04-04-2014 10:26 pm |
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24th Post |
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Jensen Healey Super Moderator 
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The E cam has 2 grooves but the lift should be 0.344". http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=12&ved=0CIUBEBYwCw&url=http%3A%2F%2Fusers.ox.ac.uk%2F~ohare%2FCam_Data.xls&ei=dyE_U5i9E-TAyAHpn4GoBw&usg=AFQjCNFoIxrFTBT3oEmFzNTI9hzg81M5_A&sig2=pf99R9nUtgm6iRIeKgSjrQ&bvm=bv.64125504,d.aWc This is an Excel spreadsheet with tons of info.
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| Posted: 04-05-2014 01:57 am |
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25th Post |
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Tom Bradley Member
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Back in the mid 90's I put a 2.2L crank and pistons in my JH5. I did not change anything else, even the cam timing was still 115/115. The off-the-line torque was much better, but I do not remember it being that much better otherwise. But then, I was not racing it, just having fun commuting to work and such.
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| Posted: 04-05-2014 08:26 pm |
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26th Post |
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carl.bedlington Member
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Hi Barthol, I will be very interested in hearing how your car goes with the 2.2 conversation. I too am building a 2.2 with 9.5:1 comp ratio, 45 Delorto's, and have a later lotus head with the ‘E’ spec cams. I have spent the money and everything has been dynamically balanced and due to be put back together after being off the road for more years than I care to mention. I bought my 2.2 crank from Gary Kemp and speaking to him he said for a road going engine I will be more than happy with it. The guys from Lotusbits in the UK said the ‘E’ spec cams were never fitted to a 2.2 engine and as a minimum I should buy a set of 107's but I am going with Garry’s recommendation as I am looking for drivability and reliability more than anything else. Please let us know how it runs, good luck. Cheers Carl
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| Posted: 04-06-2014 03:37 pm |
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27th Post |
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Barthol Member
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hi Just tested my timing and it lucks like my cams are app 252 deg with valve clearance of 0.2 mm. Inlet opens 14 deg BTDC and closes 58 deg ABDC which indicates o me that the pulleys must be 110 MOP? do anyone know at what clearance the opening and closing degrees normally is measured at? I recon that an increase in clearance will give a later opening and an earlier closing and thus a shorter opening duration all together. I knbow when i worked with old Triumph Motorcycles the opening and closing figures in degrees was always given with 0 clearance.. To carl. I think i will try to get a 104 /107 combo with 104 MOP pullies. Cheers Kim
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| Posted: 04-06-2014 07:52 pm |
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28th Post |
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pbahr Member 
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Hi lads, If you are going to purchase cams, I would highly recommend checking with Richard Reyman at West Coast Cylinder Heads: http://www.proheads.com/ Richard built up the 907 engine in YELODOG and does his own cam grinding. He did a fantastic job on my engine (240 hp) and may have some 907 cams laying around - or he can grind a set to match the other changes in your engine. He is well versed in the 907 and had several JH that he used to race. Pete Bahr
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| Posted: 04-11-2014 07:03 pm |
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29th Post |
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Barthol Member
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hi anyone who knows the normal opening and closing figures are given?? br Kim
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| Posted: 04-11-2014 07:04 pm |
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30th Post |
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Barthol Member
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sorry I meant at which valve clearance is the normal opening and closing figures of the valves given? Best regards Kim
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| Posted: 04-12-2014 02:40 am |
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31st Post |
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Jensen Healey Super Moderator
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I'm sorry I never really understood cam timing. Since the cams and pulleys are fixed, there is no adjustment to be made unless one purchases adjustable pulleys. Even then, they would be set to 104 for the 104/107 cams. Kurt
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| Posted: 04-12-2014 08:13 am |
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32nd Post |
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Barthol Member
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Hi Kurt, That makes sense:-). My problem is that I have two set of Pulleys, and I want to find out which they are. Trying to measure with a dial gauge I get max lift at 106 deg??? I measure the lift of the valve and the angle of the crankshaft close to max lift. Then I turn the crankshaft until i get the identical lift ( after the max lift of the valve), and read the angle on the degree disk on the Crankshaft. The MOP should then be directly in the middle of the 2 readings. But 106 ?? it is closer to 104 than 110. but is this way of measuring the MOP accurate enough. There is no longer colored dots on any of the pulleys Anyone now of a safe way to identify the Pulleys? Cheers Kim
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| Posted: 04-30-2016 08:58 pm |
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33rd Post |
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westsideclay Member
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I have a 75? (build date Dec.12/74) five speed which I have recently replaced the timing belt and tensioner, the tensioner quit after 41 years. When I set the engine up to 110degress on both cams there is no compression at 115 on both it 125lbs per cylinder, but spits back through the carbs. The timing is at6 degrees before TDC If is retarded more it idles at 2 grand. Help
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| Posted: 04-30-2016 09:28 pm |
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34th Post |
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subwoofer Member
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You say the tensioner "quit" on you, did the belt jump or break on you? There is not much to go on before pistons and valves meet, at two teeth off it's very close. It sounds to me like your cam and spark timing isn't even close to the ballpark, retarding the timing will NOT increase RPM unless you are over advanced to begin with.
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| Posted: 04-30-2016 11:51 pm |
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35th Post |
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westsideclay Member
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Nothing came in contact as far as valves and pistons, I've been down that road, the bearing in the tensioner broke up and the engine died as quickly as it fired. There is good compression in all cylinders and the engine fire instantly now that it is put back together but it is not right. This is my fourth go round with one of these cars and about to be my last if I cant get past this issue
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| Posted: 04-30-2016 11:56 pm |
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36th Post |
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subwoofer Member
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The Strombergs are IMNSHO a piece of s}#% and could well be the reason for the 2k idle. Check the butterfly axles for radial play, if you feel any then toss them.
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| Posted: 05-01-2016 12:32 am |
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37th Post |
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westsideclay Member
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I'd love to but cant afford the replacement Dellortos
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| Posted: 05-01-2016 05:16 am |
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38th Post |
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Randallclary@icloud.com Member
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I changed to Dellorto and have a great set of Strombergs. If you want them, make me an offer. I'm sure you would be happy. I rebuilt them prior to the stroker crank decision. Where are you located? I'm in Riverside, CA
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| Posted: 05-01-2016 09:15 am |
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39th Post |
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subwoofer Member
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I'm trying to figure out what you meant by the "no compression at 115" bit. There are a few possible culprits here: Errors in cam timing Errors in spark timing Vacuum leaks If you have the stock federal setup there are plenty of possible places for a leak to occur.
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| Posted: 05-01-2016 02:14 pm |
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40th Post |
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westsideclay Member
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No compression occurs at 110 timing the car runs at115
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