Lotus Europa Community
Lotus Europa Forums => Garage => Topic started by: Dilkris on Friday,August 23, 2024, 08:49:17 AM
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This is a bit like the "walking in sand story" :(
Couple of days back I posted in the Members Cars section under the thread "Dilkris Update - Rolling on her Wheels" and all was looking good.
This engine has maybe a cumulative total of 2 ERH's on the clock, all done in high and low idle mode; she has been completely and comprehensively rebuilt by myself with the exception of 3rd party involvement for machining works. (Crank Regrind, Cylinder Liners, New Valve Guides, Valve Seats Cut and some machining to the inlet camshaft due to the alternator pulley having spun).
Due to P.O's and unknown history I rebuilt her with a 0.070" Cometic Head Gasket to compensate for previous head skimming. With regard to the head, the only original items are the head itself, camshafts and the cam follower sleeves.
All good you would think.... :-\
I have 180 psi compression across 4 cylinders (cold) and no oil burn on the plugs although they do show signs of running rich probably due to the engine running at idle modes only; running she sounds quite sweet.
My problem is I have an oil leak from the exhaust ports on cylinders 3 and 4 - 4 being the worse. (See photo's)
My thinking is that either:-
1. I have an exhaust valve guide issue on 3 and 4
2. The head is flooding with excess oil. (I have read and seen somewhere where auxiliary drains have been fitted to the head
and also read where orifices are fitted in the oil feed in the block to reduce oil flow to the head. :confused:)
Anybody had this problem and any ideas? :(
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Yikes!
I believe there is a vent in the head that normally connects the head to the carb inlet box. Do you have that? Looking at your previous pictures, it appears to be covered...
Is any oil found on intake valves (although not seeing any may not mean much since it might be just sucked in and the oil wouldn't tend to be burned)?
Could there be an oil passage to the head near the 3 & 4 cylinders? Any evidence of that leaking?
You could do a leak down test looking for air going through your rings on 3 & 4.
Did you install valve guide seals? Are they in good shape?
Could there be a problem with your rings in 3 & 4? Ring gaps correct, Oil control rings properly installed, etc. I'm assuming your pistons are new and not worn.
I have seen many TC motors with extra venting from the cam cover - usually but not exclusively on race motors. I never paid that much attention to them but I now wonder if those were used because the normal vent from the head to the intake was blocked up since you would prefer not to sully your intake charge with oil vapors. It would not be a terrible idea to do the same but your motor shouldn't need it to prevent what you're seeing. One might expect all your guides to leak oil if that were the case anyway.
That's all I have at the moment...
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This has a vent to manifold or atmosphere? Oil level not too full?
I've never changed guides to know if that can cause oil leakage. I know people change valve spring with heads on. I would try stem seals as it would be the easiest and go from there.
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Yikes!
I believe there is a vent in the head that normally connects the head to the carb inlet box. Do you have that? Looking at your previous pictures, it appears to be covered...
Is any oil found on intake valves (although not seeing any may not mean much since it might be just sucked in and the oil wouldn't tend to be burned)?
Could there be an oil passage to the head near the 3 & 4 cylinders? Any evidence of that leaking?
You could do a leak down test looking for air going through your rings on 3 & 4.
Did you install valve guide seals? Are they in good shape?
Could there be a problem with your rings in 3 & 4? Ring gaps correct, Oil control rings properly installed, etc. I'm assuming your pistons are new and not worn.
I have seen many TC motors with extra venting from the cam cover - usually but not exclusively on race motors. I never paid that much attention to them but I now wonder if those were used because the normal vent from the head to the intake was blocked up since you would prefer not to sully your intake charge with oil vapors. It would not be a terrible idea to do the same but your motor shouldn't need it to prevent what you're seeing. One might expect all your guides to leak oil if that were the case anyway.
That's all I have at the moment...
Yikes indeed..... :confused:
I'll try and answer your comments in order - (sorry - wish I knew how to do this properly.) Here goes:-
1. The vent is there - please see attached photo - it vents nowhere atm as I have no air box installed.
2. I have not checked oil on intake valves but suspect zero as I have no blue smoke form exhaust and no oil burn evidence on the spark plugs.
3. Not sure about your oil passage comment - I believe the oil feed to the head is from the timing cover side of the block (?)
4. I have not done a leak down test (don't have the equipment) but doubt oil passing rings as this would effect compression readings which presently stand at a healthy 180psi.
5. There are no valve guide seals on a TC lotus engine - unless modified at a later stage (which is not easy and quite complex)
6. Pistons and rings are new - STD - as I had the block sleeved.
7. Agreed - why do I only have this problem on exhaust valves 3 and 4?
8. Not too sure if the works I have seen to heads is to increase venting or to improve the return of oil from the cam shaft
housings back to the sump.
In conclusion, I do not believe the problem stems from the block - everything seems to point to the head.
I know the head is going to have to come off :( :( - but I am trying to pin point what to expect.
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I’m afraid I have no better ideas…
You should know that compression and leak down tests are not really equivalent. A good compression test does not necessarily imply a good leak down test. A leak down test can give you a lot better information and they’re easy and inexpensive to make (https://www.lotuseuropa.org/LotusForum/index.php?topic=3696.msg39112#msg39112).
Good luck and tell us what you find out.
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This has a vent to manifold or atmosphere? Oil level not too full?
I've never changed guides to know if that can cause oil leakage. I know people change valve spring with heads on. I would try stem seals as it would be the easiest and go from there.
With an air box installed - the vent is connected to this and therefore the manifold - presently it vents to atmosphere.
Oil level good
Changing valve springs without removing the head on a TC Lotus is something I'd like to see.
There is no facility to accommodate the installation of stem seals on these engines - please see attached.
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I’m afraid I have no better ideas…
Good luck and tell us what you find out.
Thanks for your input BDA - the first stage will be to take the head off and see whether there is anything obviously amiss. Sending the head off to be pressure tested could well be on the cards also.
These are the challenges faced when buying a car that was in pieces. :confused:
Will keep you posted.
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CWTech had the head on TCST machined for valve guide seals .... so I installed new ones with the new valves etc. Not much room for them!
I have some anxiety about starting TCST so I feel your pain!!!
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My former boss has a habit of putting piston rings in upside down. Nice guy otherwise. The engine then pumps oil up into the combustion chambers. Many rings are symmetrical but some aren't and it is important to fit them correctly. When you pull the head, if the cylinders with the "oil leak" are clean and wet, that might be your issue.
Otherwise, valve seals as you suspect.
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Hmm, that's an interesting discovery, or as most folks would say "a real bummer".
You're right on the oil feed system and frankly I can't see how oil would end up where you're finding it under normal conditions. The feed is the front (diagram below), it goes into the cams and then floods the head. If there was a leak at the block/head interface then I'd expect to see oil outside the block, not coming out of #3 & #4 exhausts.
Although there's a drain from the head to the sump and a vent to atmosphere, both of which you've shown are in place, there's still a reasonable pressure in cam covers. If you're curious, take the filler cap off when it's running and stand back..... (no, don't try this at home, it will get messy)
So the cam followers are always flooded and even with vents in place there's enough pressure to find any weak points - look how often you see TCs with cam cover gaskets/cover nuts misted with oil.
As you're not burning oil then my first thought would be exhaust valve guides. As you say there's no seals and it's all down to machining the exact tolerance required so in theory one or two could have been reamed incorrectly. But that's a long shot, if all the guides have been replaced there's no logic that says one or two would have been machined differently to the others.
The other option, even more obscure, would be an incorrectly machined valve stem, again I can't offer that with anything other than the 1:1,000,000 chance of being right !
So if it's machined correctly then I'd look at the cam followers and sleeves.
They don't usually wear because they run in oil and on the early heads in fact the followers didn't have the sleeves the later ones had, but the oil is getting into #3 & #4 exhausts somehow.
I have read somewhere about keeping the followers in the correct order when you get the cams off and making sure they go back into their respective sleeves, so maybe there's a wear pattern involved. I honestly don't know and the reason might be the cam lobe/follower interface and nothing to do with the follower/sleeve interface, but I'm throwing that one in as a freebie.....
Personally I'd run it a bit longer and give it a few more coats of "thinking about" before pulling the head, ever hopeful that it will go away. Yes, I'm an unrealistic optimist at times.
If the oil is annoyingly persistant then I think my first move would be to look at the cam followers, lift the cams and measure the followers and sleeves on all the valves to see if some are better than others. If the followers are slack in the sleeves on #3/#4 then I could see more oil getting to the backs of the guides than on #1/#2, and I'll bet there's enough pressure from the cam cover and pumping action of the follower to push it down the guide into the exhaust port. You wouldn't see oil burning because the valve is only open when gas is flowing out
If all sleeves are identical spec then it's head off and finding somewhere who can pressure test it on the bench. I think I'd ask QED myself, they have a long history of TC heads so they might have seen similar and perhaps even a weld repair ?
Fingers crossed that swapping cam followers around fixes the problem.....
Brian
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Presumably the crankcase vent can be confirmed to be working while the engine is running? It looks pretty clean in the pic which could indicate good minimal blow-by or, alternatively, a blockage.
Got a pic of the plugs?
If they are all clean to the same extent, doesn't that kinda say the oil isn't travelling up from the cylinders? In my mind, that seems like a lot of oil for an engine that's only run for ten minutes.
If you have one of those borescopes that attaches to your phone, that might be interesting. I'm thinking brand new pistons should still be pretty clean given the minimal engine run time.
Failing that, there's only one other path the oil can take to get into the ports - valve guides.
It still seems odd this only affects 3 and 4. Does the Twink have a tendency towards oil gathering around that end of the head?
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Failing that, there's only one other path the oil can take to get into the ports - valve guides.
It still seems odd this only affects 3 and 4. Does the Twink have a tendency towards oil gathering around that end of the head?
Could be, having accidentally left off the filler cap and then running the engine I can say you get plenty of spray coming out from the exhaust cam and the cap is at the back.
The drain/sump return pipe and vent is on the inlet side so the obvious return for oil from the exhaust cam shells is along the head to the front and down timing cover. I'd expect the pressure to be equal on both sides but you've got a point, there could easily be a slower oil return/higher level above the followers on the exhaust side of #3/#4.
Brian
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Quote EuropaTC: "If the oil is annoyingly persistant then I think my first move would be to look at the cam followers, lift the cams and measure the followers and sleeves on all the valves to see if some are better than others. If the followers are slack in the sleeves on #3/#4 then I could see more oil getting to the backs of the guides than on #1/#2, and I'll bet there's enough pressure from the cam cover and pumping action of the follower to push it down the guide into the exhaust port. You wouldn't see oil burning because the valve is only open when gas is flowing out."
Thankyou everyone for taking the time to comment - my thinking is along the lines of the above. I have good compression (180psi) and no blue smoke so I do not believe the oil is actually entering the combustion chamber via either the inlet valves or via the bores; it is entering after the exhaust valves (so to speak) in the exhaust port area of the head and the only way it can get here is via the valve guides - or, (god forbid), a crack.
I have not performed a leak down test as the 180psi compression suggests no bore or exhaust/inlet valve seat problem - or is this thinking wrong?
Looking back on what I ordered and replaced during the rebuild of this engine I notice that I replaced 5 of the 8 cam followers due to visible scoring on the face of 5 of the followers - I did not replace any cam follower sleeves as not only did their appearance seem healthy but the machinist who replaced valve guides and recut the seats said the sleeves (which were/are readily available) were a nightmare to change.
As already highlighted, excessive clearance between the sleeve and follower I guess would allow the valve spring chamber to fill with oil upon which the cam follower would then act as a piston forcing oil down the valve guide.
Everything considered, this honestly appears to be the most plausible cause of my problem.
I hear you - QED are the "go to" people in this regard with provenance second to none, but my money tree is not doing so well at the moment.
I'm going to close the thread now, (thankyou all once again) and report when I know more and hopefully tell you what it was.....
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The reason I suggested a leak down test is to see if you had excess leaking through your rings. It was a long shot but I was out of ideas.
I think a leak down test is better than a compression test because it is static so not dependent on how fast the engine was being cranked. Also I think you could get a momentary high pressure that the compression test would register but you could still have excess leaking. A leak down test will also allow you to pinpoint the leak (which valve, if rings, if head gasket) and also get an indication of how bad it is. 180 psi is very good compression which I would think argues that there is no combustion chamber leaking but I also think doesn’t necessarily preclude the possibility for the reasons I’ve mentioned.
Having said all that, I think EuropaTC probably has it right and rings are not a worry otherwise you’d be burning oil.
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Turbo,
I try to stay out of the TC conversations but I hate this one step backwards.
What kind of run-in did you give the motor , RPM, Time, and total runs? If am out in left field , Please ignore.
Before pulling head I would try to clean up as much as possible and install new plugs and run again.
unless you think Its gonna hurt the engine further.
Dakazman
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As a continuation of my last comment on the 24th August, this is what I can now add to this dilemma.
I value all opinions on this forum but PLEASE don't jump in here - refer to the original post and read from there - there are pictures!! :)
The photo's really give the picture - but the "story update" is as follows:-
I pulled the head (which I REALLY didn't want to do - reassembly as we all know is time consuming and a lot of work)
I had oil on the surfaces of pistons, pistons 1 and 4 are shown, which tbh really I didn't want to see.
I had no oil track marks so to speak on both surfaces of the head gasket, (original plus cometic head gasket are shown)
I pulled piston No.1 thinking "maybe" I had installed pistons wrong way, or rings in upside down - I hadn't. Hone marks in the sleeves still prevalent. I removed and rings and confirmed ring gaps - all within spec.
As previously reported I was achieving 170,180,180,180 psi compression but filled the combustion chambers with petrol "just to see" valve seat status - levels fell to 50% equally over a period of 36 hours but that I am sure was due to evaporation.
I decided to pressurize the exhaust manifold chambers with air and made up an adapter for this purpose - I wanted to see if the chambers would hold air (40psi) or were maybe rapidly discharging air through the valve guides/tappet to sleeve running clearances, (or god forbid, somewhere else) - they were not. I WAS seeing minor leakage around the valve seats which tbh I was not worried about as quite simple valve seats are not designed to seal "backwards" so to speak.
I removed the exhaust valve from No.1 cylinder and there was zero discernable play in the guide and valve stem. (Note valves and guides are new)
I measured tappet (cam follower) to sleeve running clearances on No1 and at 8/10th of a thou - this was well within spec.
Note: I did not in any interrogate in any way the inlet valve side of the head - I have no symptoms giving any areas of concern here. Equally I did not disassemble the whole head, but concentrated on Cylinder No.1; for obvious reasons I was trying to keep disassembly to a minimum.
So..... unless I have missed something, (please chip in if I have), I am going to reassemble everything, finish the whole build and "work" the engine down the motorway. You will note from the history of this topic that I have run this engine since a complete rebuild for maybe a cumulative total of 1 hr - she starts well, high and low idles well, has no excessive crankcase pressure, has a clean exhaust and overall sounds very sweet.
Interestingly, had I had exhaust manifold gaskets that were perfectly sealing on No.1 cylinder - I would not be where I am today as quite simply I would have not been aware of any problem, (which I am now beginning to think doesn't exist). I believe the engine needs running - under load, to bed and settle the piston rings to bore relationship as quite simply, I cannot think of anything else to do. :confused:
Correction: My original post quotes Pistons 3 and 4 - this is incorrect - should have read 1 & 2, with 1 being closest to the timing cover.
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My thoughts are:-
1) Does it burn blue smoke on start-up when cold?
2) If so, does that stop when it warms up?
3) Put 500 miles on the engine, and see what happens.
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No blue smoke (or any smoke of note) when cold or hot.
Please refer "Dilkris Update - Rolling On her Wheels" in Member Cars and "Dilkris Bodywork 2227P - Help" in Garage.
It will be some time before I can put 500 miles on the engine I'm afraid.
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If it is any consolation, I have oil on plugs 1 and 4 on the car I am trying to put miles on.
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I’m still at a loss, Dilkris. The only thing I could question you about is your assertion that the valves seal better from the combustion chamber side than the port side - not that I’m saying you’re wrong. I would think there is enough pressure from the spring to keep the valve in contact with the seat with 40 psi and so I would expect it to still seal but there is no doubt that the situations are mechanically different which could affect the sealing.
I’m tempted to put it back together and run it a see if things clear up by the time it’s broken in but I realize the importance of figuring it out while it’s apart so you don’t have to go through this exercise again with a overhead cam head. If there are no ideas about what is wrong, I don’t see that you have any other options.
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:I-agree:
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Again, I'm not a TC guy, so here goes my dumb question.
Do these engines have windage trays?
Dakazman
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Is that like a baffle in the sump? If so I'll photograph and post tomorrow.
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I rebuilt my tc a few years ago. I ball honed the cylinder and fitted Deves rings to the Hepolite pistons which were in it. I had the engine apart for the water pump.
Anyway, I installed the engine and used synthetic oil.
The rings never seated because of the combination of synthetic oil I used right after the rebuild and Deves rings, which had a very weak oil control ring spring.
You could see oil on top of the pistons when the plugs were pulled. It used a lot of oil.
So, I pulled the engine, ball honed the cylinders again and installed the pistons with QED piston rings. I broke in the engine with conventional break in oil. About 500 miles.
It now uses about a quart of oil now every 2000 miles or so. There is no oil on top of the pistons.
I don't know if this is your problem, but it seems similar to my experience.
I would run the engine more with brake in oil to see if the oil consumption improves. Mine did not, so I had to remove the engine.
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Thankyou 4129R, BDA, dakazman and Pfreen for adding your thoughts - I am not clever enough with this platform to quote and comment on individual comments so I answer and comment to them altogether below:-
The sump has a baffle, (windage tray in your language?), this being to seemingly restrict oil surge and starvation to the oil pump in corners. Note the circular "polishing" that you see is caused by the spring loaded oil intake gauze, which makes contact with the sump upon fitment.
The subject of piston ring "type" and make I had not considered and as such I went through my records to see where I bought these from, (sorry at 71 you forget stuff... :confused:). The rings came complete with the pistons, (obviously), QED, and were bought from Paul Matty Sports Cars in the UK so I believe I have no reason to doubt quality.
Engine oil type was mentioned, this maybe is a contentious issue, but I ran the engine on a non-synthetic, 20/50 multigrade - would an alternative oil have been considered preferable?
Oil consumption was mentioned - but running only low and high idle for maybe 20 mins at a time, I cannot quantify oil burn.
I am seriously leaning toward "there is no problem" and putting the engine back together - hopefully she will sort herself out when under load. :holdurbreath:
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Thanks Dilkis ,
So that looks to be a baffle, not a windage tray. I’ll take it that tc do not have one then.
It may be beneficial with your new pistons . Did the manufacturer have any recommendations?
I’m sure some members will have some thoughts about its use in a TC.
Dakazman
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I learn something everyday dakazman (thankyou) and I can confirm that the TC engine does not have a windage tray - I have just Googled them and can well understand the benefit.
I am unsighted as to whether anybody has "retro fitted" one to a twin cam, or indeed, whether with such a deep sump that the ford block has, (by modern day engine standards anyway), if they would be of any benefit.
I'm sure other members will have thoughts on this.
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I doubt a windage tray would be worth it for a street motor. Usually they (with "scrapers") are used for racing engines to help keep the oil from frothing. Burton doesn't even list them for the Twin Cam.
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That slosh plate, or whatever it is called is stock twincam.
I installed a weld in baffle kit which RD Enterprises (p/n 26RE6083BK) sells and Kelvedon in England sells.
It seems to work fine.
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I installed a weld in baffle kit which RD Enterprises (p/n 26RE6083BK) sells and Kelvedon in England sells.
I cannot find reference or pictures of this - can you possibly provide?
Also - why did you deem it necessary to fit them/it? Were you having problems similar to myself?
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Dilkris they are fitted because in long right hand turns the oil moves to the left side of the pan and you can have oil starvation …. not sure that is an issue in a street car.
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We are generating confusion here between a "baffle" and a "windage tray"
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http://elantrikbits.com/lotus-elan-blog/wet-sump-or-dry-sump/
Photo of original tc sump.
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I tried to get that gated baffle e-book. They took my money, then led me to a 404 page. Has anyone else tried, or had any problems?
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Try it again, Kendo. I clicked on "click Here To Purchase the ebook" and it took me here (https://elantrikbits.com/gated-baffled-sump/). Down near the bottom of that page is a button, "CLICK TO PURCHASE EBOOK" and that gives you a little popup with a Paypal button that sets up the purchase. Good luck!
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I did the purchase, got an email from paypal confirming the charge, then got the 404 page and no ebook. I contacted elantrikbits about it, but haven't gotten a reply yet.
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In that case, I'd get Paypal to back out the purchase and do your own. It isn't that complicated. The video on that page shows enough to make your own. You can do a youtube search for "build trap door oil pan" to see how they are designed and built for different cars. You should be able to easily adapt that to your oil pan.
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I also found these:
https://mountuneusa.com/products/ford-kent-lotus-twin-cam-oil-pan-baffle-lip-seal
https://gglotus.org/ggtech/tc-oilpan/baffledpan.htm
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Sorry about bringing up this subject. I contacted https://elantrikbits.com/contact-us/ and ask them why they aren't responding to downloading a book after payment.
I like the mountuneusa product. I follow their builds on Instagram, however I never purchased any of their products and own a TC,... YET. WTS, I put out the use of a windage tray, on the thought of the piston design causes more of a vacuum, sucking more oil onto the cylinder walls. That is my opinion only, and I cannot verify since I haven't seen the piston design of either one. That is why I mentioned to check with manufacturer.
Dakazman
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I received an email see below.
Dakazman
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I just received this . See pic.
Dakazman
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Another option one might want to consider is a swinging oil pump pickup. I found this on the Documents page (you do have this bookmarked, don't you http://lotus-europa.com/manuals/).
The swinging pickup instructions are here (http://lotus-europa.com/manuals/misc/engine/36e6089s/36e6089s.html, http://lotus-europa.com/manuals/misc/engine/36e6089s/bean_swinging_pick-up_kit_004.jpg, and http://lotus-europa.com/manuals/misc/engine/36e6089s/bean_swinging_pick-up_kit_005.jpg).
The instructions are pretty scant but the URL of the pictures mention "bean" which might imply that some of the parts might come from DBE. A call over there to Ken might be helpful.
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I've only just seen this thread but think I may be able to help a little here. I've built something over 25 twincams over the years, both for road and race so I have a little experience of these engines. The OP is quite correct, there are no valve stem seals as standard which is why a small puff of smoke is not unusual when blipping the engine, a continual stream of smoke is another matter. Correct valve to guide clearance is essential but easily measured and either confirmed or eliminated as the cause. Similarly if the piston rings are at fault then there will be lots of oil present in the combustion chambers of the affected cylinders only. In this case I would be concerned about the fit of the valve guides into the head as the cambers all sound to be opretty equal interms of oil and the original pictures show an oil track down the outside of the exhaust guide where it is visible inside the port. There is no obvious sign of oil on the valve stem, so I think the oil is coming down between the guide and the head. This is quite common when inexperienced builders just hammer the old guides out and smash new ones in without heating the head first. The good news is you can buy oversized valve guides which can recover the situation pretty well. If the bore the guide fits into is horribly scored (quite common if carbon has been dragged through by the old guide) then a little "bearing fit" anaerobic sealant will work wonders. I'm afraid all the well meant speculation about camshaft followers, oil gallery location and windage trays are distractions from the primary issue here.
As an aside I wouldn't be too worried about the black sludge on top of the pistons if all the engine has done since it was built iis idled and run at light load and not really gotten up to temperature, most of that gunk is just carbonised fuel deposits that have condensed out onto the relatively cold piston crowns, especially if she is running rich at this stage.
I hope this helps, Nick