Lotus Elan

Cometic Head Gasket Modification?

PostPost by: CG901 » Fri Sep 23, 2016 3:26 pm

I had Cometic make a head gasket for my Mk1 twincam. I noticed all the holes in the gasket align with the gasket with one exception - the water jacket opening at the front of the block which on my block is tear shaped. The gasket is a bolt hole, which would restrict the flow of water. Should I cut the gasket to fit, or leave as is? I got the engine with no head gasket so haven't seen an original.
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Current: 1965 S1.5 26/4004, 1966 S3 FHC 36/5192, 1958 Fiat Abarth 750GT Zagato, 1967 Brabham BT21B, 1988 Arrows A10B-04, 1991 Brun C91-001.
Past: 1971 Elan S4/SE DHC, 1972 Europa Special, 1980 Esprit Turbo, 1988 March 881-05, 1990 Leyton House CG90105
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PostPost by: Grizzly » Fri Sep 23, 2016 4:16 pm

May be wrong but i think there all like that (round hole), i have a Ajusa Head gasket and thats the same http://www.burtonpower.com/head-gasket- ... 732aj.html

Looking at Brians picture on this thread even the Copper gaskets have round holes lotus-twincam-f39/head-gasket-thickness-t14331.html
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PostPost by: steve.thomas » Sat Sep 24, 2016 8:05 am

Just checked an old copper gasket and confirm the holes are round.
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PostPost by: CG901 » Sat Sep 24, 2016 3:36 pm

Thanks to all. Wondering if anybody has modified this gasket to better suit the underlying water passage.
Current: 1965 S1.5 26/4004, 1966 S3 FHC 36/5192, 1958 Fiat Abarth 750GT Zagato, 1967 Brabham BT21B, 1988 Arrows A10B-04, 1991 Brun C91-001.
Past: 1971 Elan S4/SE DHC, 1972 Europa Special, 1980 Esprit Turbo, 1988 March 881-05, 1990 Leyton House CG90105
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PostPost by: denicholls2 » Mon Sep 26, 2016 2:17 am

I seem to recall a thread (Europa site maybe?) discussing how you can do harm by making the modification you suggest. IIRC, the modification is to slow flow to address a cooling problem.

Unrestricted flow is not always the most desirable result in cooling system plumbing.
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PostPost by: CG901 » Mon Sep 26, 2016 7:11 pm

OK. I am convinced not to modify the gasket although I am not altogether clear exactly why the gasket is formed this way. If to restrict the flow, why?
Current: 1965 S1.5 26/4004, 1966 S3 FHC 36/5192, 1958 Fiat Abarth 750GT Zagato, 1967 Brabham BT21B, 1988 Arrows A10B-04, 1991 Brun C91-001.
Past: 1971 Elan S4/SE DHC, 1972 Europa Special, 1980 Esprit Turbo, 1988 March 881-05, 1990 Leyton House CG90105
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