Lotus Elan

Twincam Head Gasket(s) Advice Required

PostPost by: mark030358 » Wed Dec 15, 2004 1:28 am

Gents,
I've just had my head and engine rebuilt (as seperate entities) and had the engine deck heighted at the same time with the appropriate pistons fitted. However I am unsure as to fit the valve chest top cork gasket. The block is sitting approx 10 thou lower that the top of the front cover after the machining work. So will the cork compress enough to allow the head gasket to seal properly or should I just silicone instead. Any help appreciated.

cheers
MArk

ps work done by QED and jolly good it looks to.
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PostPost by: Foxie » Wed Dec 15, 2004 8:14 am

IMHO QED should have fitted the front cover when machining the block.

Sean Murray
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PostPost by: steveww » Wed Dec 15, 2004 9:10 am

Hmm 10 thou is not a lot so I would think there is enough give in the cork chest gasket to allow for this. As it happens I have the head of my twinc at the moment and the timing chest is not exactly level with the block face and I have not had any problems with this. Guess that is why they used a cork gasket in this location. Always a good idea to use a smear of RTV with the gasket as well.
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PostPost by: types26/36 » Wed Dec 15, 2004 1:29 pm

Mark,
I dont think the danger is of not compressing the head gasket, I think the problem is that the cork gasket would be squezed out and it would leak.
From memory the Lotus head gasket is + - (0.30") new and when compressed + - (0.20") thick. If the front cover is 0.10" above the block that would mean the cork gasket would have to be 0.10" thick plus a little for compression.
Think I would make a gasket from velimoid of about 10-15 thou and use a silicone seal.
If you still have the old head gasket measure how thick it is and try putting it on the block to check the distance to the timing cover.
Brian.
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PostPost by: Fred Talmadge » Wed Dec 15, 2004 1:47 pm

I found this page <a href='http://www.vellumoid.thomasregister.com/olc/68105410/gasket1.htm' target='_blank'>http://www.vellumoid.thomasregister.com/ol...410/gasket1.htm</a> describing Vellumoid's materials. Exactly which material would you use?
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PostPost by: types26/36 » Wed Dec 15, 2004 2:12 pm

I dont claim to be an expert in gasket materials so I will rephrase my suggestion to an " oil resistant gasket material"
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PostPost by: types26/36 » Wed Dec 15, 2004 3:20 pm

.........and before someone picks me out those figures should have read 0.030" 0.020" and 0.010"
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PostPost by: Fred Talmadge » Thu Dec 16, 2004 1:39 pm

Didn't mean to pick on you, was just wondering what materials folks like to use. I hope to get a few days this holiday to work on my Elan and get the head back on. And of course you know sealing up these old twinks with the newer materials is kind of an art.
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