> Hi all. I'm not exactly sure what is on topic in here, appologies if
> this is not.
I believe it's exactly on-topic here.
> I am converting a car (a lotus) from carbs to fuel injection. The
> throttle bodies I'm using have a slightly diffeerent bolt parttern to
> the carbs, such that there is enough 'meat' on the flanges, but the
> holes are too big and about half 'a hole' out, if you see what I mean.
>
> I'm thinking about filling the existing stud holes in the manifold with
> JB weld to effectively make flat undrilled flanges and then drilling and
> tapping that. This will mean the drill/tap will be working half in alloy
> and half in jb weld.
>
> The jb weld packet seems to suggest you can tap it - in reality does
> anyone know if this will work?
JB Weld will take threads, but they aren't very strong. However, I'd be
surprised if you can tap a hole that is half in aluminum and half in JB
Weld. Since the JB Weld is so much softer, the tap will want to hog in on
that side, at the very least you'll wind up with an oblong, off-center hole.
At worst, the JB Weld plug will break loose and try to turn.
I believe you'll have the same problem to a lesser extent by trying to fill
the hole with another bolt, unless you can make it brass or aluminum. IMO
welding is the best approach, even if you have to take the manifold to a
shop to be welded.
> Should I go for a course thread like UNC, or a finer one (metric or
> UNF)?
I believe coarse threads would be best here, either SAE or metric.
Randall
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