Michael :
On the early/late TR4 exhaust valve, the only difference is the stem
diameter. All it takes to use the late valves in an early head is a
special valve guide (which has a larger od to match the larger hole in
the early heads).
Looking at the Moss catalog, I would guess the TR6 exhaust valve changed
head diameter, since the seat insert seems to be the only other thing
that changed. Since BL was looking for more performance (to make up for
smog losses), I'd guess the later valve has the larger head. But, these
are only guesses !
Randall
"Michael D. Porter" wrote:
>
> What's the difference between
> early TR4 and later TR4/TR4A exhaust valves, and early and late TR6
> exhaust valves?
|