[Aaron]

Got some fine tuning issues going on here. Please feel free to offer advice.

My Dads 67 cruiser has a 350 with a 4 speed and 3.55 gears. The 4 speed is a M21 and the rear is just a 8.2 with a locker in it.

The motor is basically a zz4 short block with a UDHarold hyd. roller cam with 280/288 and 226/234 @ .050 duration with .530/.530 lift on a 108 lsa. The compression is right at 10 to 1. Heads are Brodix 180IK with Crane Energizer rockers. Intake is a RPM air gap with a Holley 650 Double pumper. Dizzy is a Stock GMPP HEI with a blue and silver spring in it with a aftermarket module.

Timing is set at 36* all in by 2600 and the can has been modified so that it 12* of additional timing for a total of 48*. The initial timing falls to 19* and with the can hooked up idles at 31*.

We are having some slight run of issues. Not much.

The throttle blades are turned so that idle is right at about 900 rpms.

Once you have taken the car for a spin and shut it off it will not die there is slight hickup and then shutters off. We run nothing but 93 octane in the car.

If I put in first gear and easy the clutch out while turning off the key there is no issue.

If I turn the throttle blades down another quarter turn, there is no run on, but the car seems to struggle to stay cranked while idling . When you turn the throttle blades back up a 1/4 turn, it idles fine.

Anyone have any suggestions?

 

[chevelle swed]

What is sec. blades adjusted ? try to open them a little and close the primary 1/4 turn and/or try also adjust the air bleeds in a little for a richer mixture.

 

[Aaron]

What is sec. blades adjusted ? try to open them a little and close the primary 1/4 turn and/or try also adjust the air bleeds in a little for a richer mixture.

The secondary blades are turned all the way in, so that the screw touches the lever.

Are the air bleeds even adjustable on a stock Holley 650?

This combo made 420 horse and 410 torque on a chassis dyno.

Cranking compression is right at 195 psi.

 

[chevelle swed]

excuse me! translation error, meant of course the idle mixture screws.

 

[Aaron]

excuse me! translation error, meant of course the idle mixture screws.

Ok, understand.

The mixture screws are about 1 and 1/2 turns out from being all the way in.

I used a vacuum gauge to tune for highest vacuum and this is about where Im at.

 

[chevelle swed]

Highest vaccum + 1/8 turn out otherwise the risk is that it is too lean

 

[Aaron]

Highest vaccum + 1/8 turn out otherwise the risk is that it is too lean

Basically it sounds like your saying to screw in the screws to only a 1/8 turn out from the bottom to richen it up.

 

[72BBMonte]

Basically it sounds like your saying to screw in the screws to only a 1/8 turn out from the bottom to richen it up.

I took it he said adjust for best vac. then add 1/8 of a turn out from that.

 

[bracketchev1221]

I took it he said adjust for best vac. then add 1/8 of a turn out from that.

Me too. But on the secondaries, there is an idle speed screw for the secondaries as well. It is a set screw under the base plate. If the primaries are open too far, you can crack the secondaries more to get the primary shut. Or you can look up secondary idle bracket or something. It goes on the secondary shaft and allows you to adjust the idle speed without taking the carb off.

http://www.summitracing.com/parts/qft-63-2/overview/

 

[Aaron]

I see what you guys are saying now.

Ray, thats a interesting link you provided.

I have the set screw to those secondary plates turned in so that it just touches the lever.

 

[Steve Johnson]

 

[427L88]

Right at 1:25 or so. I've always "cracked the secs open so the transfer slot is **just** peeking out from below the butterfly. Yank the carb off and give it look see from underneath.

 

[kettbo]

just for reference
if you close the idle SPEED / throttle blades fully, then 2.5 turns open sets the front edge nicely on the idle transfer slot

 

[Dave69Z]

for the secondaries you can take the screw out and put it in from the top side instead of buying the adjustable bracket. Then with the engine off open secondaries and turn screw a little and retry til you get it where you want it.