Ed :
Just spent some (more) time trying to measure it. I am reasonably
certain it is not 1/4-28 (Unified National Fine), but I'm still not
certain if it is BA 0 (.2362 inch x 25.5 tpi x 47.5 degree thread angle)
or 1/4 BSF (.2500 x 26 x 55). Since most of the other threads on the
carb seem to be BA (British Association), I'm inclined to believe the
former. My 26 tpi gauge also seems to show more error than the 25 tpi
(which might actually be 25.5).
But, since the seal here is formed by the body of the union pressing
against the flat outside of the carb body, not by the threads, I would
guess that 1/4-28 is "good enough".
Randall
fogbro1 wrote:
>
> Randall,
>
> Speaking of vacuum advance, what' the thread size on the TR3 carb where
> the vacuum line enters? I threaded a 1/4 fine bolt in there yesterday,
> seemed to fit. Is that right?
>
> Ed
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