[TR] TR4A head gasket, 87 mm cylinders

[Jerry Van Vlack]

I’m interested in the responses too as I recently suffered a head gasket failure around the intake shroud of #4 using a 91 mm Cometic (very similar to the Lucas new improved one) In my case the head is milled .090 using 87 mm liners. The old Payen style lasted 30 or more years until I did a valve job 4 years ago. The Cometic lasted 4 years until it failed. I’ve discovered some extenuating circumstances which may have caused my failure but I am interested in the responses, especially from those who have moved up to the 89 mm liners. How have you sealed the 89’s and or is it too early to report results? Also please indicate if you’ve milled the head and by how much.

I’ve discussed this with some very reputable Triumph performance folks in the last week and gotten some good input but would like to broaden the discussion.  Once we see some responses I’ll be pleased to share what I’ve discovered. Those who I’ve already discussed this with can chime in or not, I will include your advice but not who you are unless I have your permission. But I’d like to hear some input from others before I do that.

Regards,

Jerry Van Vlack aka JVV
66 TR4A



From: asg123 at centurylink.net 
Sent: Wednesday, September 20, 2017 1:51 PM
To: triumphs at autox.team.net 
Subject: [TR] TR4A head gasket, 87 mm cylinders

I have asked a similar question before but my mechanic and I are still undecided which rabbit hole to enter

Does anyone have experience with which head gaskets hold up best against blowing out around the combustion chambers?  I see the stainless steel composite gaskets which claim to be the best.  But, some people, including the tech support at BPNW, say that the OE copper gasket by Payen withstands high compression the best.  How does the German made Payen copper gasket hold up compared to the Lucas OE type copper gasket?   We had an OE copper head gasket blow out between cylinders #1 and #2 after only a few thousand miles. It was using 93 octane gas with the timing retarded a couple degrees to keep down spark knock, but it still dieseled on when we tried to shut it off.   A solid copper head gasket from Gasket Works custom milled to drop the compression to 130psi fixed the spark knock and dieseling, but we had chronic problems with the oil and water weeping into each other no matter what sealants we tried. As always thanks for your responses.  Arnold 



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