I am new to the list so first I will give a
brief introduction:
My name is John Walker
I live in Everett Washington (Just North of Seattle)
I own an early 1974 MGB which I purchased from
it's second owner in 1993.
The car appears to be all original with the exception of the
pre-emissions cylinder head which I installed last year.
Like I said, I have an early 1974 MGB with the stock 18V engine, stock
distributor, stock HIF carbs and stock intake manifold.
The question that I have is regarding the vacuum advance on the stock
distributor. As it is currently installed, the vacuum for the vacuum
advance is derived directly from an unregulated (full vacuum) port off of
the intake manifold. When I set the timing I do it with this vacuum
advance disconnected as indicated in all of the literature I have read.
Then, after the timing is set I reconnect the vacuum to the distributor.
Since the vacuum port is un-regulated, this basically causes the
distributor to constantly run in an advanced state, thus raising the idle
to about 1100 RPM's. The car runs great, however I can not get the idle
down below about 1100. I would prefer to run the idle in the 700-900 range.
I know on the older HS style carbs, the vacuum for the vacuum advance is
derived from a metered port on the back side of the carbs, however the HIF
carbs do not seem to have this feature.
Am I missing something?
Should the vacuum be derived from a different location? If so, where?
Am I missing some sort of regulator?
Is the vacuum hose supposed to be anything other than standard 1/8" vacuum
hose?
Any direction you can give me on this would be greatly appreciated.
Thanks for your time.
~= Early 1974 MGB =~
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