Holley Carb tunning questions - Team Camaro Tech
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post #1 of 10 (permalink) Old Jul 10th, 03, 02:48 PM Thread Starter
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I just installed a 3310-2 750cfm carb and I am having troubles tuning this carb. I have never owned a holley before so I am starting from scratch. It fired right away and seems to run down the road "ok" but I can't get it to idle right. I had to turn out the idle screw all the way out and it still idled at 1000. Then I drove it and started up again and it wouldn't idle at all so we had to turn the screw in and then it ran. As it sits now it will idle but it surges slightly. I have the mixture screws 1 1/2 turns out and when I adjust them the idle goes up and down just like if you were adjusting the idle screw. WHen I drive the car I can tell that it still needs some tweeking, it feels like it could rev a little faster than it does. I am trying to get this set up ready for saturday when I take it to the Dyno. I am not sure if they are gonna help tune or not. THnks for all the help.

69 Camaro RS, 383ci,10.5-1 AFR 195's ported, Comp 286HR, 4340 forged Crank & Rods, JE Pistons, RPM Airgap, Holley 750 HP carb, 350 turbo w/ shift kit, 3000 Coan, Be cool, caltracs,12bolt 355 eaton posi..Best E.T. 12.22 @ 112

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post #2 of 10 (permalink) Old Jul 10th, 03, 03:58 PM
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Sounds like your on the idle transfer circuit. May need to open air bleeds up some and/or check to see that the "slots" aren't uncovered too much.

The "slots" are in the primary venture, on the front side < towards radiator > and should only be uncovered about the thickness of the butterfly.

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post #3 of 10 (permalink) Old Jul 10th, 03, 06:13 PM
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Also, there is an adjustment on the secondary throttle blades. It's on the passenger side, but on the bottom where you can't get to it without taking the carberator off. I've seen two different adjustment specs for it. Back it out until the throttle blades close then open them 1 turn, and the other spec was 2 turns.

Most people with big carbs and big cams have to open their secondaries to keep the idle circuit working properly. Bog and hesitation make it necessary to open it in some cases. Perhaps your problem is the opposite - it is open too far.

It's also possible that you have a vacuum leak. How are the idle mixture adjustments?

-dnult

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post #4 of 10 (permalink) Old Jul 11th, 03, 04:01 AM
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The secondary stop screw is usualy not adjusted unless you realy need the air on a big cam. It is usualy turned in only a very small amount past the point where it starts to budge the secondary butterfly assy. About 1/4 turn is all I would go unless you need the air. It is realy only there to prevent the butterflys from sticking in the venturi bore. We use it for other purposes at other times.

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post #5 of 10 (permalink) Old Jul 11th, 03, 06:00 AM
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I've got to agree with Mark on this one. Holley publishes 1/4 turn and my '69 Chassis Service Manual shows the holley equipped car having it set at a 1/2 turn. I always recomend resetting it when someone has an idle circuit problem for good measure.

69 - what screw are you talking about? The one that opens and closes the pri throttle blades or the rich/lean idle mixture screws?

I as well as others have published a couple books worth in the forums. Search on "holley" and my member number (186) in some of the forums, start in "Performance". I think your will find all you need to know about that carb and your problem...

...Dennis

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post #6 of 10 (permalink) Old Jul 11th, 03, 07:11 AM Thread Starter
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DJD

THe screws that i am talking about are on either side of the bowl facing the radiator. I have now been able to smooth out the idle so that it doesn't surge the only problem is that now the car idles ar 1200 rpm. THe idle spped screw is turned all the way out and it doen't affect it any. I just need to figure how to set every thing from scratch. I assume that thoes scres on the side of the bowl are the mixture screws. am I correct or is there somthing else i should be looking for?

69 Camaro RS, 383ci,10.5-1 AFR 195's ported, Comp 286HR, 4340 forged Crank & Rods, JE Pistons, RPM Airgap, Holley 750 HP carb, 350 turbo w/ shift kit, 3000 Coan, Be cool, caltracs,12bolt 355 eaton posi..Best E.T. 12.22 @ 112

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post #7 of 10 (permalink) Old Jul 11th, 03, 10:26 AM
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Look at the choke. There is a fast idle cam that will hold the primary open for cold start conditions.

It is on the opposite side of the primary butterflies from the idle speed screw. There is a small adjustment screw that rides on a stepped cam. The cam and screw exist with both manual and electric choke carbs. I bet that is your problem.

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post #8 of 10 (permalink) Old Jul 11th, 03, 07:45 PM
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Quote:
Originally posted by 69CamaroRacer:
THe screws that i am talking about are on either side of the bowl facing the radiator.
Sounds like you're talking about the idle mixture screws and not the idle speed. Idle speed is on the drivers side throttle shaft.

As for the secondary stop screw, I've got the holley manual in my hand and it says 1 full turn. I believe my rebuild kit said 1 1/2 or 2. In any event, this adjustment will affect where the primary throttle blades ride with respect to the idle slots.

There are several good suggestions in this thread. Choke, fast idle cam, plugged idle air bleeds....

-dnult

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post #9 of 10 (permalink) Old Jul 11th, 03, 09:11 PM Thread Starter
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UPDATE: Well I have figured out one of my problems. The choke has been removed and when you push on the side of the carb where the choke was you can hear a hissing. SO there is a vaccume leak. So upon a suggestion i applied some jb weld/ tyoe ouddy over the srew holes in hopes of possible stopping the leak. Does this sound right? Second problem that I have discovered is that I have to adjust the linkage fo that it oepn the blades all the way. THa could have been a major factor in the slow revving under a load. Any way I will continue laying with it and will poast my dyno numbers tomarrow. Thanks for all the sugestions.

69 Camaro RS, 383ci,10.5-1 AFR 195's ported, Comp 286HR, 4340 forged Crank & Rods, JE Pistons, RPM Airgap, Holley 750 HP carb, 350 turbo w/ shift kit, 3000 Coan, Be cool, caltracs,12bolt 355 eaton posi..Best E.T. 12.22 @ 112

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post #10 of 10 (permalink) Old Jul 11th, 03, 09:23 PM
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Quote:
Originally posted by dnult:
As for the secondary stop screw, I've got the holley manual in my hand and it says 1 full turn. I believe my rebuild kit said 1 1/2 or 2. In any event, this adjustment will affect where the primary throttle blades ride with respect to the idle slots.
Are you talking about the primary or secondary throttle blades? Download the "Carburetor Rebuild and Adjustment Manual" on this page. http://www.holley.com/HiOctn/TechSer...o/FMCTech.html

...Dennis

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