Re: [Amc-list] Nick Frank or Davis - thermostats

[Tom Jennings <tomj@xxxxxxx>]

Nick knows tons more than I do, listen to him! I can tell you one
(embarrassing) thing -- I ruined a newly-built motor (304v8,
long ago) with a bad distributor. The mechanical advance had
failed and I was running with not enough spark advance. At low
speeds it would cool right down, but on the highway it got very
hot. Burned valves and piston tops!

Grossly speaking, less advance, engine runs hotter; more advance,
cooler, up to where it pings. The reason is simple -- with late
(less advance, retarted) spark, the burning fuel runs through
the head into the exhaust, and dumps heat into the cooling
system. With lots of advance, the fuel is fully burned and
goes into expanding gases pushing the piston down, and does
work aka torque! That little detail takes the heat out of the
soon-to-be-exhaust.


Simple check:

Put a timing light on it.

Pull the vacuum hose off the distributor. Rev the engine to 2500
rpm.  Should see 20 or more degrees advance from idle to 2500.

Back to idle. Put a vacuum pump or idle vacuum onto the vacuum
advance.  You should see about 20 degrees of advance from that.

If either of those fails fix the distributor!

Running vacuum advance at idle often results in a cooler motor at low
speeds/idle.
_______________________________________________
Amc-list mailing list
Amc-list@xxxxxxxxxxxx
http://splatter.wps.com/cgi-bin/mailman/listinfo/amc-list