On my '64 TR4 with Strombergs the tiny hole into the carburettor throat is
just prior to the throttle butterfly valve (between closed throttle flap and
air piston) meaning the vacuum advance system is not working at all during
idle. As soon as you open the throttle flap just a little the hole is right
there and the vacuum gets at it thereby sucking in the vacuum diaphram
advance plate which is attached to the points plate which advances the spark
- but only by a few degrees for a CT 22326.
Carl
'64 TR4 since '74
<<The bottom line is that at idle, the vacuum advance is pulled in by the high
vacuum in the inlet manifold changing the timing. When you open the
throttle, you let in more air and bring the vacuum in the manifold closer to
zero, allowing the vacuum advance to move back to it's static position. So,
the question is whether the engine is advanced or retarded as the vacuum
decreases or increase.
Listers, can anyone shed some light on this issue?>>
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