Easy way to tune a carb?

[StephenC 10]

So I was installing a new Lokar bracket with a TPS mount the other day and bumped the set screw for air fuel ratio. And now its running a little rich I think. I dont know much about tuning carbs hardly anything. its a Barry Grannet road Demon carb 4 barrel double pumper 625 CFM with electric choke. Wondering if theres an easy way to set air ratio and tune it to make the car run a little better??

[foothilltom 33]

Are you talking about the idle-mixture screw (one on either side of the primaries) or the spring-loaded idle screw or something else?

 

When you say it's running rich, what do you mean? Fast idle? That could be a result of improper idle-mixture, choke related, or a vacuum leak to name 3 possibilities.

 

Perhaps you could describe the behavior at idle, the behavior at constant throttle, and the behavior during acceleration to focus us on the problem. It's hard to know what you mean by "run a little better". They are all pretty different systems depending on the answer.

 

FWIW, messing with the idle-mixture screws can definitely impact idle. If you only messed one up, take a small screw-driver to the screw on the opposite side (the one you didn't bump) and carefully count how many turns it takes to seat that screw (be precise). Back that screw out to the same position it was, then do that same thing with the mal-adjusted one. In short, they should both be set the same. Make sense?

 

More info would be helpful.

Tom

[bigperm2 10]

Also, if you go to the barry grant website, you can download their instructions on how to set everything. It is one of the best writeups on how to tune barry grant or holley carbs that I have ever seen.

[1952 10]

Are you using a vacumn gauge ??

 

You could get a A/F meter to tune the carb

[StephenC 10]

Sorry I posted this in a hurry. Idle is fine and WOT is fine its just that if I start the car and let it warm up when I first put in it gear it stalls. Then after I let it warm up enough to see my temp gauge move and put it in gear its fine. Its never done this before I bumped the idle mixture screws just wondering a quick way on how to properly set them.

[foothilltom 33]

Hey Stephen, are you following panteramatt's recent thread about stalling? There's tons of good info in there; particularly some stuff about setting your idle-mixture.

[panteramatt 1]

Was just gonna mention that.

[StephenC 10]

No I just read over it and read your comments. Its time to bust out the vac gauge and go screw with it for a little while thanks.