Vewwwwwy interesting.
re: " A fully screwed in spark plus will not screw all the way into the
combustion chamber."
If I am interpreting this correctly, this means the plug is not fully seated in
the plug hole. Is that correct? If so, you'd probably have leakage around the
plug threads; i.e. the copper gasket would not be crushed and hence would not
seal. All the plug gaskets I have removed appear to have been crushed. Or, does
this just mean the plug threads are too short?
Also, would a hotter plug compensate somewhat for this?
bs
--------------------------------
Bob Spidell - San Jose, CA
There is a huge ignition static advance anomaly between the factory
specs for a BJ8 and every earlier 12 port 3000.
The closest explanation for this i can offer is that the later 12 port
heads are machined incorrectly by the factory where the spark plugs
screw in. If anyone on the list has a bare later 12 port head, you can
confirm this. A fully screwed in spark plus will not screw all the way
into the combustion chamber.
It screws in all the way on every other westlake designed head ive
ever seen There are a few threads still exposed in the head on the
late 12 port heads. Meaning the plug has to fire earlier because it is
further away.
I thought this issue was the reason for the bizzare amount of static
advance on a bj8, but apparently the same late model head is used on
pre BJ8 cars.
Either way, a total of 34 - 36 total advance "all in" at 3,000 -3,500
rpm is correct for all bmc c series engines. How you achieve it is up
to you (I.e combination of static advance plus distributor advance)
I have very little advance in my distributor compared to a std BJ8
(changed the distributor cam, and no vacuum advance)
Chris
www.myaustinhealey.com.
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