----- Original Message -----
From: "Warren Allen" <warren-allen@triad.rr.com>
To: "Triumphs list" <triumphs@autox.team.net>
Sent: Wednesday, May 19, 2004 10:09 PM
Subject: Finding carb vacuum leaks with propane torch
> Okay, somebody please explain to me how to use a propane torch to find a
> vacuum leak. I assume that, with the engine running, you turn on the torch
> gas (unlit) and move the torch around where a leak might be occurring.
Where
> there's a leak, something changes in how the engine is running. Faster?
> Slower? Rougher? Am I close, or way off? Thanks for the info.
>
> Warren Allen
> 1960 TR3A TS55177L
Warren-
You are correct in your assumptions, the torch is unlit and the engine
is running. Engine should be at normal operating temperature if possible. If
you are doing this outside, be sure there is very little to no wind present.
Some listers have already heeded the safety warning of propane and spark but
given the fact that the carbs and intake manifold are on the opposite side
of the engine as the dizzy, you should be OK. It doesn't take the propane
set to full flow to detect a leak, a light to moderate flow typically will
show a leak as the engine vacuum will pull the propane into the leaking
hose, throttle shaft or carb spacer (or whatever else is leaking). The
engine RPM will rise when the propane goes into the combustion chamber as it
enriches the A/F mixture. Your leak will most likely be at the carb throttle
shafts, carb spacers, intake manifold to cylinder head or a vacuum hose.
Another way to verify that it is a vacuum leak is to attach a vacuum gauge
to the intake manifold. If vacuum is low (below 13" or so) and the needle is
steady, this would indicate a vacuum leak present as well.
Good luck
Tim Hutchisen
71 TR6
80 TR7 Spider
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