<VV> 102 PG idle adjust

[cmot at ix.netcom.com]

When I was tuning up distributor ignition GM's one item that I always used
to check whether modern HEI or points, especially if the engine was cold,
was the cyntrifugal advance mechanism. What I found on older, high milage
engines was that the lubricant on the distributor shaft between the shaft
and the cam lobe mechanism would varnish up and stick, not returning to the
fully retarded position at idle. 

Take off the distributor cap and twist the rotor and release, it should snap
smartly back. If the return is slow, or quick with the last part moving
slowly like one of those slick new soft close drawer mechanisms they put on
kitchen cabinets these days, your lube has seen better days and needs to be
replaced. If the engine is hot on bad lube it will appear to work ok, when
cold it will work slower or not at all in severe cases.

This has the effect of causing inconsistant timing settings and idle speeds.
When it heats up the unit will advance and retard more normally. When the
engine is run cold the advance will apply but the springs will not be able
to return the cyntrifugal advance to the idle rest position. It is not a
weak spring issue. The advanced timing will cause a higher idle. If you
re-adjust the idle speed and or mixture, you will be chasing your tail and
wondering what the heck is going on. Luckily because of the Corvairs gear
driven cam you do not have to factor timing chain wear into this sort of
diagnosis which was another issue I used to see on other engines.

If because of the sticking cyntrifugal advance you are setting the timing
incorrectly. What might happen is that after warming up fully the mechanism
frees up enough to work somewhat properly. You shut down the engine and it
returns to base timing, the lube re-hardens and everything cools down and
locks in the new position. You restart the next day and the choke and fast
idle takes care of initial performance issues. Once choke comes off you find
that idle is lower and you have a hesitation from retarded timing, that is
until the engine warms up a bit and it start to advance some, but
performance it is not entirely correct because the timing was never set
correctly through no fault other than not noticing this issue.

I used to see this problem a lot. You have to pull the distributor, remove
the drive gear and slide the whole thing apart on some distributors. It's
been so long since I did the early Corvair distribuors I don't recall if
they were assembled the same way (some makes of distributors disassemble
from the top) but the problem was the same. I had inherited a stock of the
original Delco distributor lubricant in large tubes, it was black with
specks in it that made it look like some of the more modern moly greases
available. What the original composition was I am not sure. I can get the
part number if people need it.