4 corner idle VS 2corner circuit adjustment

Posted By: hankcrank

4 corner idle VS 2corner circuit adjustment - 08/17/11 08:32 PM

I have read many posts on the idle mixture screw adjustments on Holley carbs.I read 1-1/2 turns out for a starting point on all carbs. I have read 3/4 turn out for a starting point.
I have been told from cab. experts 1-1/2 turns out on a 2 corner carb. and 3/4 turn out on 4 corner idle circuits.
Does anyone know for sure what is the right amount of turns for a starting point? 3/4 to 1-1/2 is quite a difference.

Posted By: 67_Satellite

Re: 4 corner idle VS 2corner circuit adjustment - 08/17/11 09:39 PM

A starting point is just that. You're going to adjust it up and down anyway. If it starts with the screws 3/4 turns out, and runs long enough to make your adjustments,it will be o.k.

Posted By: Cab_Burge

Re: 4 corner idle VS 2corner circuit adjustment - 08/17/11 10:03 PM

I would tune it to make you happy

I like and use from 1/4 turn to 1 full turn on most of my motors with big cams idling at or under 1000 RPM, I do open the idle bleeds up to help lean the idle circuit down also

I like to see from 14.5 to 15.8 AFR on my wide ban, that does make it cold blooded to start when cold but so what

Lean is mean

Now if I can get the part throttle near 14.0 or above I'll be good

Another thing to use on tuning the idle circiut is to stand at the rear or side of the car where the exhaust exits and smell it, if it is rich you will smell it, if it is not rich it won't stink as bad, even with good smelling race gas

One other last thing, if you can start the car cold and it idles right away your probally on the rich side on the idle circiut

Posted By: Bob_Coomer

Re: 4 corner idle VS 2corner circuit adjustment - 08/17/11 10:25 PM

Quote:

I have read many posts on the idle mixture screw adjustments on Holley carbs.I read 1-1/2 turns out for a starting point on all carbs. I have read 3/4 turn out for a starting point.
I have been told from cab. experts 1-1/2 turns out on a 2 corner carb. and 3/4 turn out on 4 corner idle circuits.
Does anyone know for sure what is the right amount of turns for a starting point? 3/4 to 1-1/2 is quite a difference.

No one can say what your engine will like.. Every engine is diff. Cam size plays a roll, way to many variables. If your interested in learning how to properly tune your engine, get a base line and start making changes... Only one change at a time though...

Posted By: steeldust

Re: 4 corner idle VS 2corner circuit adjustment - 08/18/11 01:14 AM

Quote:

Quote:

I have read many posts on the idle mixture screw adjustments on Holley carbs.I read 1-1/2 turns out for a starting point on all carbs. I have read 3/4 turn out for a starting point.
I have been told from cab. experts 1-1/2 turns out on a 2 corner carb. and 3/4 turn out on 4 corner idle circuits.
Does anyone know for sure what is the right amount of turns for a starting point? 3/4 to 1-1/2 is quite a difference.

No one can say what your engine will like.. Every engine is diff. Cam size plays a roll, way to many variables. If your interested in learning how to properly tune your engine, get a base line and start making changes... Only one change at a time though...

I AGREE 100% YOU ARE RIGHT BOB.

Attached picture 6783070-JUNEBOUNTYRACE.jpg

Posted By: jbc426

Re: 4 corner idle VS 2corner circuit adjustment - 08/18/11 10:26 PM

Given that the timing is set correctly, the air bleeds are properly sized and throttle blade position at idle is covering the correct amount of the idle transfer slots, I run them 1/2 to 3/4 of a turn out from lean mis-fire.

Screw them out just until the idle will no longer increase, then screw them back in until it starts to lean mis-fire (idle decreases) then back out 1/2 to 3/4 of a turn. Go around until they are all consistently 1/2 to 3/4 of a turn out from lean mis-fire. it may take several times to balance/stabilize them.