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Author Topic:   Holly 4412 (Hay KP)
hollywoods62
Member
posted June 15, 2003 11:34 PM
Hay KP you seem to be the man,
I have a 40 over 350 9:1 comp. 465 lift 270 dir. 114 sep. stock ex and int. 993 heads with 205 int. 160 ex. (no valve size rules) I run at 5000 ft. in reno area , Have 73s in now, BUT i CAN'T get off the corner good ! any help would be great

Thnx Hollywood62

KPLugnut
Member
posted June 16, 2003 08:28 AM
Part of the problem isn't carb related, it's that 114 lobe separation on the cam.
Your very thin air only will require slightly smaller jetting, and btw, you're running the same size jets that Holley sends with that carb as "stock".
Your idle circuit and accelerator pump circuit probably aren't doing their job for you if the carb has sluggish throttle response or stumbles when the throttle is nailed.
Have you set the idle mixture screws and throttle places vs. idle transfer slot according to the common procedure? How much of the idle slot is exposed underneath the butterflies? How far out are the idle mixture screws? What power valve is in the carb, a 5.0 is what comes stock.
Just some more info needed before I can pinpoint where we can help.

KPLugnut

hollywoods62
Member
posted June 16, 2003 11:49 AM
Ok the power valve is 7.2, the bottem of the idle circuts are exp. idle screws are out 1 turn center squirter is a 32 , I will pull vac. later today.

thnx Hollywood62

KPLugnut
Member
posted June 16, 2003 12:32 PM
There's no such thing as a "7.2" power valve. Could you mean 7.5? Or possibly a 5.0 power valve with a "7" as the number portion of the date code which also is stamped on the PV's.
If it's a 5.0, that is what comes stock with the 4412, BTW, and will fill the needs of many applications.
Perhaps, is there a delay in accelerator pump arm's contact with the pump? This will cause a stumble off the corners, too.
Also, a .032" squirter will possibly deliver too much too fast on initially slamming open the throttle.

Just some thoughts, and let us know what you find for a vacuum reading at idle.

KP

hollywoods62
Member
posted June 18, 2003 11:16 AM
Ok i got off my **** and pulled vac. its at 12in at idle

thnx Hollywoods62

KPLugnut
Member
posted June 18, 2003 11:26 AM
OK, with that vacuum at idle, you'll be fine with a 6.5 or even an 8.5 PV. Anything larger, and you may find it causes other issues with the PV circuit and mid-range driveability.
Perhaps too much of the idle transfer slot is showing while the butterflies are closed?
And is there zero play in the accelerator pump arm?
What color pump cam is on it?

I still tend to lean towards that long lobe center cam, tho....

KP

hollywoods62
Member
posted June 18, 2003 12:01 PM
The cam is tan, was thinking of going to a 28 nozzle?

Our cam rules call for a min.of 112 , ISKY said this is the best one for my app.

thnx Hollywood

KPLugnut
Member
posted June 18, 2003 12:36 PM
The .028" squirter change will delay how long it takes for the remaining fuel to be delivered from the accelerator pump. If you're coming off the corners at, say, half throttle and nailing the pedal to the floor and the car stumbles, it could in fact be because your accelerator pump shot is used up. In that case, a smaller squirter may aid you a bit. Even as small as .025 or .021 is not out of the question.
Float level thru the corners (and hence, fuel slosh) has some to do with throttle response as well.
But again, if the car is sluggish any time it's below a certain rpm, but otherwise does not hesitate, miss, blubber, etc., then it is not usually a carb or fuel problem....it is in the cam choice, and how that affects the power band of the motor.

Hope that helps,

KP

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