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| Carburetors | Rating: 
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| Posted: 04-21-2005 12:59 pm |
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1st Post |
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Brett Gibson JH5 20497 Member
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Hello all, I'm looking for some advice from the "been there done that" group who have installed Dellorto's, I am presently in the install mode and so far things seem pretty straight forward but what I'm looking for is how poeple have handled what to do with the crankcase breather hose, on the Strombergs I removed it use to feed into the aircleaner feeding the carbs, but on the Dell's I'm using new aircleaners that are seperate, one for each carb, the same ones John Kimbrough is using, see his site http://home.comcast.net/~jrkengr2/html/pre-assembly.html Now do I run a hose down under the car and let it breath off there, and if I do will it create a mess with oil vapor all under the car, drips, dirt etc. or should I try and plumb the breather tube into the back's of the new cleaners, one or both cleaners, or then again I've seen oil catch reseviors attached to the fire wall should I be going that route, any help would be appreciated, Thanks in advance. Brett.
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| Posted: 04-21-2005 04:28 pm |
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2nd Post |
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Judson Manning Member 
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Brett, Letting the crankcase vent under the hood is like filling you house full of gasoline vapor and waiting for it to find the pilot light on your gas stove.....EXPLOSIVE! It's also not very ecologically friendly... This is what I did on my car: http://shorpac.com/v-web/gallery/album08/910_907_hybrid2 I'm actually using my windshield washer bottle as a catch-can to keep oil from dumping into the carbs. Using a MK1 vapor-separator would look cleaner as I did for Hugh Furr's car. Judson
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| Posted: 04-21-2005 06:26 pm |
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3rd Post |
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Greg Fletcher Administrator 
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Judson, you get extra credit for all that tubing! Pretty fancy stuff. I simply ran a hose out of the engine to an aftermarket charcoal vapor filter I clamped on the the hose. It was simple, effective and a whole lot better than having fuel vapors moving around the engine compartment.
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| Posted: 04-22-2005 03:51 pm |
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4th Post |
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Brett Gibson JH5 20497 Member
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Thanks for the info, I think I will try and pick up one of those JH oil tanks that go on the firewall but in the mean time run a long hose out the back, I dont really want to cut holes in my nice new air cleaners just yet. Thanks agian Brett.
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| Posted: 04-24-2005 05:31 am |
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5th Post |
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Jay Dee Member
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I installed a longer hose and vented it down below the bell housing. So long as the engine is in good condition, you should experience no dripping or make a mess as you say. Being vented to the atmosphere below the bell housing, I cannot see how there would be even a remote potential for explosion as has been suggested. If you do indeed have a bit of a blowby problem, then the suggestion to first of all vent it through a condensing chamber to capture any oil makes perfect sense. As far as the environment goes, I don't suppose it amounts to a hill of beans whether it is vented out the crankcase or first burnt in the combustion chamber then exhausted out the tail pipe. It's still pollution; live with it. J Dymond
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| Posted: 04-26-2005 03:34 pm |
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6th Post |
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Judson Manning Member
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J- JHs tend to have a lot of blow-by by nature of the piston-to-wall clearance, and to complicate matters, the engine wasn't originally designed for Positive Crankcase Ventilation. The MkI's crankcase ventilation was so much an afterthought, they needed the vapor separator I mentioned. The JH5 incorporated more 'positive' ventilation by adding the tube from the oil filler neck to the airbox. It didn't get 'perfect' until the Esprit had to start passing emission requirements 10+ years later. The blow-by gasses contain much more unburned hydrocarbons (HxCx)than they do combustion by-products (H2O, CO2, NOx, etc.). These unburned hydrocarbons are what contaminate your engine oil, and cause smog. It's the same principal as cows breaking-wind (methane C2H4) contributing to global warming. By routing the blow-by back into the engine, it at least gets the chance to be burned into H2O & CO2 instead of being vented directly to the atmosphere as HxCx. The trick is to keep oil from contaminating your intake...hence the separator. Granted, the JH isn't the most ecologically friendly vehicle on the road....but I'm at least trying to do my part to save the planet. Judson
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| Posted: 10-28-2005 08:51 am |
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7th Post |
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Tony Hollart Member
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I am getting quite a bit of sump oil coming up from the crankcase breather tube. The engine has had new rings fitted and the compression when hot are Ok at 100 psi for each of the cylinders. I hope this improves with a bit more running, but the oil is actually building up inside the fibre glass air cleaner fitting. So far the engine has probably done 15 hours running. It seems to drain most of the oil back down the tube again but there is a layer of oil in the housing that cannot escape. Reading Judsons comment on blow by it seems to be a documented problem, but I am surprised how much oil is getting blown up. Has anyone else had this problem with a fresh engine? Thanks Tony H.
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| Posted: 10-28-2005 04:32 pm |
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8th Post |
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Mark Rosenbaum Member 
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With good valves and properly seated rings you should see 125-130 psi in each cylinder (at sea level -- 10% less at an altitude of 4000 feet or so). If your engine has been run for 15 hours -- the equivalent perhaps of 500 to 1000 miles of driving -- and you still have only 100 psi compression, quite possibly the rings are not wearing in properly. If so, that would be the most likely cause of your excessive blowby. Are you using synthetic oil at present? The stuff is not supposed to be used during a break-in period as it is such a good lubricant that rings etc. will not wear in properly.
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| Posted: 10-28-2005 07:20 pm |
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9th Post |
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Judson Manning Member
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Tony, When the engine got new rings, did the mechanic have a machinist hone the cylinder liners? and no, that 3-stone shoe honer you attach to a drill doesn't count... A very common freshman mistake is failure to address the quality of the liner-bore during a rebuild. I've seen this happen in all makes and models of cars. The best rings in the world can't compensate for liners that are out-of-round or have significant taper. Exactly how much is too much??? Anything over .002" won't allow the rings to seal. Judson
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| Posted: 10-28-2005 08:32 pm |
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10th Post |
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Tony Hollart Member
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I am not using synthetic oil at all, I use Castrol GTX a 20 - 50 W oil on the engine. I have just recently changed the oil in the engine , less than 1 hours running on a new oil and filter. Just out of interest I cut open the oil filter that had been on the engine ( spun on the lathe to cut ) to see what had collected in the filter elements, just normal bits of gasket goo and the odd very small flake of metal trapped in the filter element. Which was a good sign that the engine was clean when reassembled. This problem did not happen on the first lot of oil. At ths stage I will carrying on running in the rings and maybe need to work the engine a little harder to get them bedding in. I have not revved out past 5000 rpm yet. I took the block and pistons to our local machine shop for checking and honing of the cylinders, on their OK I went ahead with new rings and a hone only. I did do the reassembly myself but did not encounter any problems while putting engine back together. Thanks for the feedback. **** UPDATE **** Caught out by the simpilist mistake you can make, engine oil level too high. Checking on the dipstick when the oil level had settled it was way over. Drained out 500 mls of oil and it came back onto the full mark OK. At the time of filling it is such a slow process to fill up I must of lost count of how many litres were already in and howw much was still to drain down. Last edited on 10-29-2005 12:48 am by Tony Hollart |
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| Posted: 03-15-2006 07:32 pm |
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11th Post |
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colinw59 Member 
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Who makes this Charcoal vapor filter and were did you get it? Also do you have any pics. Thanks
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