[Fot] use of BRONZE GUIDES

[Enquiries Road & Track]

in our engine shop, we avoid bronze guides unless we really have to use
them such as with some specially coated titanium valves

cast iron guides last for a very long time under very arduous conditions

about the only OE manufacturer that I've seen that routinely uses a bronze
guide is M Benz, and they are a very special product and only used in some
of their engines

not all bronze guides are equal. we have encountered numerous grades. all
of them are notoriously difficult to size. we have special tooling to deal
with them.

there is an argument that some types of bronze guides can run lower
clearances and therfore improve heat transfer from valve stem to guide. i
have never seen any documented or visual proof of this .

IMHO, especially with older cars like TR's, they are mostly a marketing
fad, with unscrupulous vendors appealing to the 'go faster" set

Terry