Jim---I've used the "bronze" valve guides for almost 20 years. (I put the
second set in about 5 years ago, when doing a valve grind) Absolutely no
problems with these, OR the unleaded gas, which came to my area about the same
time. 20 years, in my case, equals about 150,000 miles.
I don't understand why any pressed-in guides would "fall out". They should
begin as an interference fit. I'm not absolutely sure about this, but I think
that these guides should tighten up, rather than loosen up, when things got
hot. Metalurgists in this crowd may want to add something to this.
Dick
-----Original Message-----
From: jim hearn
Sent: Tuesday, February 17, 2009 1:53 PM
To: 'TR6'
Subject: [6pack] Bronze valve guides?
I thought I had seen on some posts that bronze valve guides were the way to
go with a TR6 so now that I need to do a complete valve job, I bought bronze
guides to do it. When I took it to the machine shop (that has a good rep
for doing British stuff), I was told that they had quit putting in bronze
guides due to the extra heat in the combustion chamber caused by the new
fuel with no lead. They said that early on when they were using bronze
guides with the new fuel, due to dissimilar expansion rates for the
different metals (head and guides), guides were loosing up and falling out.
Has anyone heard this, experienced this, or have any information on this.
Is anyone running bronze guides successfully? Mine is a stock motor but if
this is true, there doesn't seem to be enough good points for the bronze to
risk the calamity. Any thoughts? Jim
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