Hi Everyone,

I have an 87 Formula Firebird 5spd with a Carb'd 305 VIN H with 120000 miles. Lately the car has been dieseling when I shut it off, continuing to sputter for 2-10 seconds, randomly. It seems to do it 50% of the time. Also, sometimes it seems to skip when shifting, probably at about 1500 rpmI've searched through the archives trying to find info, found a couple of things.

My idle speed in neutral is 1000 rpm. That seems way too high to me, can someone confirm this, and tell me the proper idle speed? I'm hoping the idle screw fixes that. Would lowering this solve my dieseling problem? If not, what else would cause run-on?

Also, today while shutting the car off with the hood open, I could see fuel spew out of the carb when it was shut off and diesled...a foul smelling gas fume fills the air when this happens. Thanks in advance for your replies, I'm eager to fix this cause I know how bad diesling is for engines and I don't want mine to be ruined!

Steve

 

Your timing is off.

 

Your timing could be off, but I would be inclined to suspect carbon build up in the combustion chamber plus a high idle speed.
Check your timing, clean out your combustion chambers, and try to adjust your idle speed to around 600 to 700 rpm in drive.
"how do I clean out my combustion chambers you ask?"
Well for the low low price of a glass of water (atf is a good substitute, about 3 or 4 ounces) dribbled into the carburator of a running engine, you too can have sparkling clean combustion chambers.
All standard disclaimers apply, so if you completely destroy your engine, it ain't my fault.