Calling the Holley carb experts

[bucket]

Also, do the secondary butterflies fully close? There's no idle air screws on the rear block, so it could be pulling from the secondary jets if not.

 

[Dman1049]

Are sure about that? It shouldn't.



I'm leaning this way also, the transition slots may be uncovered. But why?


Has the thing actually been driven, or does it run too poorly to drive it? I realize it runs rich at idle, but how does it run elsewhere and under load? How many turns out are the idle air screws? Have you looked down the throat of the carb while running, looking for an obvious defect like fuel dribbling out from anywhere it shouldn't be at idle?

1.25 turns out. Under load is fine. Seems to have good power. No stumbles. I haven't looked to see if fuels dribbling or doing anything funny

 

[Ricko1966]

Transition ports is what we are talking about. The throttle stop screw is there to stop the throttle plates from sticking in the bores, but a lot of people crank them in to make a car idle. When you crank it in it uncovers the transition ports which provide fuel to prevent stumbles as you accelerate. If they are uncovered at idle you're pulling extra fuel from them at idle.Make sure the throttle stop screw is not cranked in.

 

[Dman1049]

Transition ports is what we are talking about. The throttle stop screw is there to stop the throttle plates from sticking in the bores, but a lot of people crank them in to make a car idle. When you crank it in it uncovers the transition ports which provide fuel to prevent stumbles as you accelerate. If they are uncovered at idle you're pulling extra fuel from them at idle.Make sure the throttle stop screw is not cranked in.

Transfer slots are barely open. Open the secondary throttle blades a little more for more air. Guess it is what it is

 

[Ricko1966]

Transfer slots are barely open. Open the secondary throttle blades a little more for more air. Guess it is what it is

Back the throttle stop screw off. You need to be idling on the idle circuit, not the transition circuit.

 

[Dman1049]

I thought a little square or .02 to .03 was supposed to be seen?

 

[Ricko1966]

Where is your vacuum advance getting vacuum from? Ported or manifold vacuum?

 

[Ricko1966]

My guess is your running ported vacuum and don't have enough advance at idle so you've twisted the stop screw in to compensate. Switch to manifold vacuum and back the throttle stop screw off.

 

[Ricko1966]

Do some research find out if anyone is drilling holes in the throttle plates for more air. Or hell call Holley.Drilling holes in the butterflies is an old school trick.

 

[Dman1049]

Back the throttle stop screw off. You need to be idling on the idle circuit, not the transition circuit.

My guess is your running ported vacuum and don't have enough advance at idle so you've twisted the stop screw in to compensate. Switch to manifold vacuum and back the throttle stop screw off.

Hows the idle speed increased after that? If I screw it to where the transfer slots are closed it won't idle. Idle mixture screws don't bring the idle up... Unless they are supposed to. Running manifold vaccum to the vac advance

 

[Ricko1966]

By hooking vacuum advance to manifold vacuum it brings in more timing at idle, which speeds up the idle. Hook to manifold vacuum then see if you can close the throttle plates more and still maintain idle. I bet you can. Then by not pulling fuel from the transition ports at idle your rich at Idle condition goes away.

 

[Ricko1966]

You must be registered for see images attach

Reading in a Holley forumn it turns out it is common to have to crack the primary too far which exposes too much of the transition port.The fix is crack the secondary a little and close the primary. Going to try to put up a screen shot. But first are you running at least 20 degrees btdc at idle with vacuum advance connected?

 

[80BrownK10]

By hooking vacuum advance to manifold vacuum it brings in more timing at idle, which speeds up the idle. Hook to manifold vacuum then see if you can close the throttle plates more and still maintain idle. I bet you can. Then by not pulling fuel from the transition ports at idle your rich at Idle condition goes away.

He said before this post he is useing manifold vacuum for advance.

 

[Ricko1966]

He said before this post he is useing manifold vacuum for advance.

I thought that was a question not a statement. As in. Running manifold vacuum to vac advance? As opposed to, I am already running manifold vacuum to vacuum advance. I wonder if his vacuum advance is working?

 

[bucket]

You must be registered for see images attach

Reading in a Holley forumn it turns out it is common to have to crack the primary too far which exposes too much of the transition port.The fix is crack the secondary a little and close the primary. Going to try to put up a screen shot. But first are you running at least 20 degrees btdc at idle with vacuum advance connected?

Without having 4-corner idle screws, I'd drill the primaries before cracking the secondaries open.