How to build an oil tight twincam?

[h20hamelan]

Here.

viewtopic.php?f=39&t=47993

So thanks 2cams70, good one. 12th post in link

[marode]

You can use the rubber sump seal at the rear IF you change the rear seal carrier to the later design,

Brain, are you referring to this part?
https://www.burtonpower.com/rear-oil-se ... fp306.html

Do you think it’s worth converting to the rubber seal?

[marode]

What is the Clearance on the Valve Guides.

Now I know: inlet is 0.04 to 0.05mm (in spec but a bit towards the maximum), Whereas exhaust is 0.03 to 0.05 which is s bit too narrow (should be 0.06 to 0.075).

[ncm]

That's the part.
Is it worth changing your current cover? Probably not as you still have to use the cork seal at the front so will be unable to use the Cometic gaskets that are cut too short.
Brian.

[2cams70]

You can use the rubber sump seal at the rear IF you change the rear seal carrier to the later design, however you cannot fit the rubber front seal as the groove in the timing case is narrower on the twincam (the same as early crossflow and the precrossflow ) than it is on the later 711M engines.To claim that this :-https://www.burtonpower.com/cometic-lotus-twin-cam-timing-case-gasket-set-c4491.html fits the twincam really is out of order as the sump gaskets in this kit are for the 711M style engine and will not work with the cork seals as shown in your picture.

Brian.

Possibly. You can only successfully use the later design rear carrier if the raised lip inside the sump recess where the carrier fits is in the same position as the later sumps (1973 onwards) intended to be used with this carrier. It's not something I've checked personally. As another poster said - the timing cover is always going to be cork anyway. Trying to convert is not something I've ever bothered with. The Nitrile rubber seals will harden and lose compression over time just like cork does.

[Hawksfield]

Hi 2cams70

That's something new in all the discussions around TC sump seals, that the sumps are different between post1973 and pre 1973 TC six bolt sump pans, that's something to be aware of

Thanks for your input

I once used a rubber halfmoon from a xflow gasket set and the rear seal distorted and finally leaked that accounts for it.

[rgh0]

Hi 2cams70

That's something new in all the discussions around TC sump seals, that the sumps are different between post1973 and pre 1973 TC six bolt sump pans, that's something to be aware of

Thanks for your input

I once used a rubber halfmoon from a xflow gasket set and the rear seal distorted and finally leaked that accounts for it.

The Lotus Twink 6 bolt sumps twin cam up to the end twin cam production of did not change and always match the narrower cork rear seal and carrier as far as I am aware, but whether the later post 73 Ford sumps were changed to match the wider rubber seal I dont know but by then I think they were not making front bowl sumps for Kent block engines except for Lotus ?

cheers
Rohan

[tonyabacus]

See if you can get hold of Brian Buckland, currently he has been doing some work in this area of too much crankcase pressure and has been in some long conversations with regard to different piston manufacturers and variations in bore honing as a likely culprit for this problem. I know he has been investigating exactly the same symptoms as those you described in your original topic.

Brian comes on the forum only occasionally so send him a pm
Tony

[marode]

I can tell some new perceptions in my case. Gave the block to a machine shop for measurements and to discuss the options. One notable finding was that the piston compression ring gaps were far too small (almost nothing). Also the block bores appeared in a polished finish, although at least some sort of pattern had be added to the bores only about 8000miles ago. This may all have resulted in poor sealing of the compression rings. I am a bit angry with the shop were I'd given the block to for assembly last time, they'd told me the rings were ok to use and I was relying on the "experts" as this had been my first engine overhaul.

I can only advice everyone to measure and double check things yourself, cause nowadays you are obviously dealing with idiots, at least in Germany.

[phil1800]

The frog green cover colour was choosen by it‘s Canadian owner. It‘s not original, but I keept it anyway.

Lots of oil in the plug recesses. Thanks to the opening at the back of the head, this oil find s its way to the clutch housing and further back

My S3 engine leaks heavily from the head cover. Oil sits in the spark plug recesses in the head, and leaks both on front and rear from the cover. The engine has received new gaskets after an engine fire only 2 years ago, but was not assembled by myself. The cork gasket may be compressed to much, but other than that I can‘t think of any obvious mistakes. Any advice how to get the head cover tight?

[gjz30075]

It may be warped. Put it on the head without a gasket and see if there's 'daylight' anywhere. You might
have to mill the cover slightly to get it flat.

[cabc26b]

I recently went through this - FWIW

The covers do warp - I looked there first - checked seal using a feeler gauge, doubted that i had a good seal , went to the trouble to machine a spare cover flat and fit that . Got a better seal however still weeped oil - checked crank case venting and that was also an issue - addressed that and it cured it . Ultimately went to yet another cam cover and added additional breather on the cam-cover ( race style on the front between the cams ).

[h20hamelan]

My guess is if oil is allowed to accumulate on-top of the gasket, it has more opportunity to find a way out. Ive taken to trimming the gasket, and once lightly bonded to the cover, add a bead of glue (well cleaned) to channel any oil away from the sides.