Tuning a 350

[zombieking]

OK, so I have read how to tune my carb properly with a vacuum gauge, and read how to time the engine with a timing light. Which do I do first? My guess would be timing, then carb. I know it seems simple, but I have forgotten my basic engine mechanics after owning a fuel injected vehicle for the past 22+ years and only needing to turn the key and let the computer do all the rest of the work.

I did lots of work on old vehicles back in highschool and my early 20's, but seem to have conveniently lost that info in my brain. The other problem is I dont know what the 350 in my 81 Grand Prix came from, or what year. Just know it has the rocker cover bolts around the outside which means it isn't a newer style I think.

So, what should I do first and what timing should I use. Even a redirect to a previous post would help. I'm going through so many old posts trying to find the info I need, but not sure if it applies to my engine. I see a good Pontiac Service Manual in my future when I can afford it!

Thanks!

 

[zombieking]

Sorry, further info I left out. I believe it's a fairly stock 350, but has headers and dual exhaust. A holly 600 with electric choke rides on top of an aluminum intake of some sort, but not sure I can identify brand or further details of it. I will also be changing the plugs, and putting new leads on. It has an Accel distributor, but I only have a new rotor for it at this time. The THM350 behind the engine has a stage2 kit in it. No A/C or smog stuff on the engine.

I know it's running rich at the time and the idle doesn't settle down very well off choke. It run a bit rough but timing may fix that I hope. Hopefully didn't leave out anything important.

 

[carguy1959]

More than likely it's your carb. Running rich most of the time means too much gas not enough air. I would change and check old plugs for fouling. Is this something that has just happened or has it always run rich?

 

[zombieking]

I bought the car only a month ago. Haven't driven it too much yet. Just know it isn't quite right by the rough idle. Manifold vacuum at idle with advance plugged is about 12. When driving, if I put my foot down from a dead stop, it stumbles a bit til she gets some rpms into her, then goes like stink. I guess what I was really asking if someone brought you a car to tune up, which would you do first, time then set the carb? I figure that one is better performed before the other.

 

[85GPLef41]

i would do timing first then carb and then double check timing. Sounds like your carb either needs adjustment or a rebuild.