Andy Moltu Posted October 14, 2021 Report Share Posted October 14, 2021 Noticed something interesting whilst mulling over head gaskets. A friend has just rebuilt his engine (with machining work to the liner seats). Only to find that his head gasket blew almost immediately. On taking the head off the 89mm liners were too low - approx 2thou. (Presumably an assembly measuring cock up) Obviously that will need adjusting with shims/Fo8s. He was advised to use a copper gasket this time rather than the composite one he used initially. Looking on line there seem to be 3 types of gasket - composite and copper as mentioned already but additionally there is a steel one (not come across that one before myself). Anyone got any reasoning behind which one might be better? Quote Link to post Share on other sites
RogerH Posted October 14, 2021 Report Share Posted October 14, 2021 Hi Andy there was a silly spat in TRAction a couple of issues ago where somebody complained that the new 4 pot heads where made wrong (no they are nor not) as they had a couple of head gasket failures. The answer appeared to be that with 89mm liners you need the solid gasket as one or two areas are a bit thin for the composite gasket. Roger Quote Link to post Share on other sites
stuart Posted October 14, 2021 Report Share Posted October 14, 2021 (edited) 12 minutes ago, RogerH said: Hi Andy there was a silly spat in TRAction a couple of issues ago where somebody complained that the new 4 pot heads where made wrong (no they are nor not) as they had a couple of head gasket failures. The answer appeared to be that with 89mm liners you need the solid gasket as one or two areas are a bit thin for the composite gasket. Roger Mine runs fine on 89mm with a composite gasket, they are actually recommended for that size of liner. Ive not seen a steel gasket, theyre usually used as a shim to lessen compression where too much has been taken off either head or block rather than as a gasket per se. Stuart. Edited October 14, 2021 by stuart Quote Link to post Share on other sites
Andy Moltu Posted October 14, 2021 Author Report Share Posted October 14, 2021 Mine is on the composte gasket too with 89mm liners and when I fitted it seemed an excellent fit with the fire rings lining up nicely on the liners without protruding into the combustion chamber. Only done 100 miles since rebuild to find out! Quote Link to post Share on other sites
trchris Posted October 14, 2021 Report Share Posted October 14, 2021 When I fitted 89mm liners I also used a composite gasket as recommended by TRGB so far all ok Chris Quote Link to post Share on other sites
BRENDA1 Posted October 14, 2021 Report Share Posted October 14, 2021 I also have a composite gasket on my 89mm piston & liners rebuild feb 2020 and done 6851 Miles and still running well. Mike redrose group Quote Link to post Share on other sites
RogerH Posted October 14, 2021 Report Share Posted October 14, 2021 39 minutes ago, Andy Moltu said: Mine is on the composte gasket too with 89mm liners and when I fitted it seemed an excellent fit with the fire rings lining up nicely on the liners without protruding into the combustion chamber. Only done 100 miles since rebuild to find out! Hi Andy, my post does not really answer your query as you had sunken liners. There is no reason the composite should not fit correctly with both original and new heads Roger Quote Link to post Share on other sites
Drewmotty Posted October 14, 2021 Report Share Posted October 14, 2021 Are we talking at cross purposes here? The standard gasket which is a composite of a number of materials surely will not fare well with 89mm liners whereas the composite gaskets sold by Restorations are specifically designed for use with modified heads and big liners. The steel shim gaskets were a copy of the competition gasket supplied by Triumph and work well with careful assembly. I've used all three types and a solid copper gasket to good effect, although I am extra careful when using a steel shim or solid copper gasket which needs a good annealing prior to fitting. I favour the expensive Racetorations composite gasket as a fit and forget option for long term use or a solid copper gasket to adjust the compression ratio or if you expect to be regularly disturbing the head. Quote Link to post Share on other sites
ianc Posted October 14, 2021 Report Share Posted October 14, 2021 For information: Revington offers solid copper gaskets in a various thicknesses from 0.5 to 2.5 mm. I have been running with solid copper gasket (two, actually, in order to get the compression which best suits me) on 88mm liners for 28 years. Ian Cornish Quote Link to post Share on other sites
MichaelH Posted October 14, 2021 Report Share Posted October 14, 2021 Some people follow the Kastner book and open up the cylinder head around the inlet valve to unshroud the valve to increase flow - and also grind away the inside of the liner to the same extent. This causes problems for composite gaskets as the integrity of the gasket is damaged if it is cut away to match. Solid copper can be cut away to match the liner/head without the problem. I think this was the cause of the problems mentioned above. If the Liners are left intact any gasket should work Next problem comes fro the height of the liners above the deck. I run copper gaskets and try to get 2 thou height and as long as the height is equal across the head it works , I suspect 4thou 2 thou 4 thou is asking too much from a copper gasket, a composite gasket might be more forgiving. MichaelH Quote Link to post Share on other sites
Andy Moltu Posted October 14, 2021 Author Report Share Posted October 14, 2021 5 hours ago, RogerH said: Hi Andy, my post does not really answer your query as you had sunken liners. There is no reason the composite should not fit correctly with both original and new heads Roger For clarification it wasn't mine that sunk. And the initial build was with a composite gasket. (Not being smug just yet as I've not had the time to get too many miles on mine since putting the engine back.) I think one of the other issues is that the head had had quite a lot of the shrounding relieved. He hadn't relieved the top of the liner to match but I guess if "too much" of the head shrouding had been taken away it could be possible there wasn't enough of a seal on the fire rings and it let go. With only 2 thou' that may well have limited the pressure. Not sure if there is any disparity of the liner heights. It is strange that the liners that were apparently clamped and measured in the usual manner (by a long standing 4 pot owner who has had his engine apart lots of times who was helping him) can have dropped by a few thou'. Steel Fo8s apparently. Got a feeling I might get roped in next week so seeking collective advice. He spoke to someone at TRE who adviced copper gasket and shims to increase the liner heights. Quote Link to post Share on other sites
RogerH Posted October 14, 2021 Report Share Posted October 14, 2021 Hi Andy, the relieving around the inlet valve was the main concern with the new heads that TRGB were moaning about Pete Cox suggested that a solid (copper) gasket is what should be used p 89mm liners and new head (or with relieved shrouding.) Roger Quote Link to post Share on other sites
TorontoTim Posted October 18, 2021 Report Share Posted October 18, 2021 On 10/14/2021 at 9:04 AM, Drewmotty said: I favour the expensive Racetorations composite gasket as a fit and forget option for long term use or a solid copper gasket to adjust the compression ratio or if you expect to be regularly disturbing the head. +1 Quote Link to post Share on other sites
Andy Moltu Posted October 18, 2021 Author Report Share Posted October 18, 2021 2 hours ago, TorontoTim said: +1 Tim, I take it that you are not a fan of the solid copper gasket? On 10/14/2021 at 5:44 PM, RogerH said: Hi Andy, the relieving around the inlet valve was the main concern with the new heads that TRGB were moaning about Pete Cox suggested that a solid (copper) gasket is what should be used p 89mm liners and new head (or with relieved shrouding.) Roger It's funny how opinions differ - I was advised to use the composite gasket on 89mm builds by someone who has built some of the most powerful TR engines over the years. He did warn me not to remove too much of the shrounding around the inlet valve. In the end of the day I decided to get my head done professionally by CNC heads who used their kit to do the head work using a known good flowed head profile. (Didn't get away with that one with the "Bank Manager" at home) They left pleanty of metal to avoid compromising the shrouding. Quote Link to post Share on other sites
TorontoTim Posted October 18, 2021 Report Share Posted October 18, 2021 7 hours ago, Andy Moltu said: Tim, I take it that you are not a fan of the solid copper gasket? I haven't used one, to be honest - I don't trust my skills with the annealing process, apart from anything else. I used to use steel shim head gaskets on my rally Vitesse, but haven't (yet) gone all-metal on the TR. Tim Quote Link to post Share on other sites
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