adjusting choke on a stock carb 350

[1985gmc350]

this may or may not have been asked a lot on these boards....i don't know, i just registered....sorry if it has.
anyways, i have an old beat up 1985 GMC suburban 1500 with a 350 with the stock 2 barrel carb.

as can be expected with a carb, it stutters and runs horrible when it's cold, until the engine gets warmed up. however, it recently has got warm enough that it shouldn't run so rough, and it continues to run horribly. it's running very rich (black exhaust smoke, hard idle, low MPG, stumbles when i rev it, etc.) and i'm occasionally getting a CHOKE light that stays on after the car starts and continues running. i assume this car is has an electric/automatic choke, but i'm not sure.

i drive a camaro during the summer that has TPI, so fixing a problem like this is much different with it.

can i adjust the choke at all on the suburban? if so, how? also, where can i set the idle on this engine, and can i adjust the timing manually, or is it computer controlled like on a fuel injected motor? if i could adjust any or all of these three, it would help immensely, as the motor runs very rough right now, and dies frequently. my gas mileage is also horrible (much worse than when i drove it during the summer). sorry for asking what seems like a dumb question, i guess. if it was a camaro i could fix it, lol . thanks.

[KShortell]

The choke light is actuated by an oil pressure switch. If your idle rpm's drop too low, it'll come on-- not necessarily a choke problem.

There's no computer, no ESC (Electronic Spark Control), etc. on your 350. The factory 350s were like this up through '86. You do have an electric choke, though.

To be honest, I haven't had to screw around with my carb in all the years I've had it, although I did farm out the choke replacement about 3 months ago when I was having all the valve stem seals, rear main seal, etc. replaced. I was having a cold start/cold idle problem.

The idle speed and mixture adjustment screws are straightforward carb stuff. You shouldn't have to adjust the mixture screw, however. That would require an exhaust gas analyzer to really get it right. That's why they're set at the factory and have the tamper-resistant stuff on 'em.

Setting your timing is a manual affair. Again, you have no computer. It's a standard HEI with vacuum advance only. Your spec. should be 8 deg. BTDC at idle rpm. Full mechanical advance (no vacuum connected) should be no more than 32-34 deg. BTDC max. at 3,000 rpm.

I hope this helps a bit...

Good luck!
Kevin