Corellian Corvette

Had a cold start problem this AM I've never encountered before. Think I might not have done a good job adjusting the fuel mixture

Car runs great warmed up, has a real lope and bog when cold.

When adjusting the mixture screws..

1. Do I leave the air filter on or off?
2. Using a vaccum guage, I turn the screws out until I achieve best idle, then 1/2 turn after that?

Does that sound right?

Thanks!

ROD NOCK

Correllian-
This is assuming that you have the stock Q-Jet set-up. It's your choke that plays a part in cold start and running. There's an initial adj for your choke closing, and a 'vacuum break' adj for a 'pull-off' action that opens choke butterfly a given amt. Along w/fast idle RPM adj. It's the vacuum break adj that will give good drivability until the choke is off.
As for the idle mix, here's a quote from Lars carb adj tech paper. Good info: p4. Tweak your idle screws.
Screw both of the screws in until they gently bottom out, and turn them both out 1-1/4 turns. This is a good starting point. With a tach on the engine to monitor rpm, start the engine and turn the screws ½ turn at a time, turning both screws the same amount, until the best rpm reading is observed. Then turn them in 1/8 to ¼ turn to lean it out just a tad. Once set, I like to shut the engine off and turn both of the screws all the way in, counting the turns, until they gently bottom out again. Just to make sure they’re both set the same. Then back them out to the setting you had.
Good Luck -Rod :chevy

Corellian Corvette

Yes -- normal Q-jet.

What about air filter? On or off?

marky mark

I adjust mine with the air filter off for convienance. The service manual says keep the air cleaner on while doing this procedure. Not sure it matters a whole lot.

Regards, Mark :flag :chevy

Corellian Corvette

Thanks man!

Any other suggestions here? Does the procedure change with the air filer off as opposed to on?

Right now I'm using a vacuum guage and doing it with the air cleaner on.

Adjust mixture screws out until I achieve best vacuum, then turn in 1/4 turn to lean out.

Does this sound right?

Phlash

Yep, but choke setting is crucial on cold mornings. Most people that I have work with seem to set the choke too tight.

Phlash 72 BB Roadster :seeya