With the problem you describe, it sounds like your idle speed/mixture is
also a bit off. You'll need a vacuum guage and a timing light. Set your
timing according to the emissions label, or perhaps a bit more, 14-16 won't
hurt. Remember to read the label where it directs to pull the vacuum line
from the distributor and plug it. After doing that, set idle speed with the
set screw at the side of the carb, using the emissions label to verify the
RPM, about 700-800 would be correct. The idle mixture screws probably have
cap limits on them, you'll have to eliminate them in all likelyhood. Use the
vacuum guage, connected to the base of the carb, to adjust idle mixture to
the point where you get the best vacuum reading. Double check rpm, reset if
needed. Now double check timing, and verify the correct setting with your
RPM adjustments made. This should cure the dieseling problem.
The reason all this is happening is because the idle mixture screws are
"limited" in how far you can turn them, which is fine when the truck is new,
but not now. So instead of adjusting the idle mixture, they've used timing
and idle speed to compensate for poor idle mixture.
"There are four boxes to be used in defense of liberty:
bad, bad word, rebuild! tim, i hope he's not right. do what max says
first -- his advice is bang on -- and i really hope that's all it is.
weak under load -- not good -- we know
if budd's right, you might want to hot plug the weak cylinders and get
rid of it (or rebuild as budd says, or throw in another motor if you
have one, rebuild later)
i have an 86ish with a weak cylinder #5 on my SL6, and the plugs get
carboned up way to quickly although only carbon out exhaust on startup
-- think I'll drop in my other SL6 (well, not on my own) as soon as the
bloody thing will go more than 2 blocks and i can get it home
my 91 dodge 318 i sold for $100 -- didn't need it -- there are some good
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