holley question

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mod38-1

mod38-1

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Need some help with holley tuning. Have a 72 duster with 360 Engine has 13 to 1 compression Heads done by muscle motors Camshaft is mechanical 557 lift with 296 duration (engine was originally built for alcohol oval track car). Carb is a 750 holley with proform center dual 50cc acc pumps. Have tried several squirter sizes from #31-#46 all with about the same results. Total timing is set at 36 Rear axle ratio is 486 is a auto car with a 2500 stall converter. The problem is on take off car stumbles for a few seconds and then pulls very good, also when driving if you give it gas it hesitates for a second then goes and this happens at all speeds also car seems to flood very easy. Have tried a 650 carb and with this it does not flood as easy but same hesitation. Spark plugs appear to be good, light brown in color. Car is ran on strictly turbo blue race fuel due to compression. Any help would be apprieciated ,
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Thanks
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That combo needs more converter.
What air bleeds are in the carb ? The Proform body should have came with a few sets.
 
air bleeds appear to be marked 36 but hard to tell. I agree I need more converter just had this stuff from other projects and wondering if any way to try to tune around it
 
secondary opening time is o.k. ignition is mopar performance unit without vacuum advance the sad thing about this is it stumbles bad enought on take off that it will not spin the tires or brake stand but when it shifts from first to second you have to let off gas or tires do not hook up
 
I am trying to think here....Cant remember if the MP dist uses the weights or not(brainfart)Might want to work through some jet changes also
 
plugs appear good in color but there is a lot of cam in car, engine needs to be above 1000 rpm to idle and at idle it has 10in vac and in gear at idle only has about 3in vac Has 2.5 power valve I know this combination is wrong but i had all the stuff already and just want to take it to dragstrip for a day as over winter it is going to be changed Thanks
 
:munky2:There is a screw for the cam on the carb you can change that Sometines fixes your issue. this should fix your problem:burnout:
 
How does rev when not under load and in nuetral? Does it rev clean? Do you get a black cloud?

I agree that this combo needs much more converter and this may be difficult to work around.

You might want to try a 1.0" power valve but before that, have someone drive behind you and see if you get a black cloud on stumble from take-off.

Also, you may want to see if you can borrow a Mallory or MSD distributor and lock out the mechanical advance. You may need much more initial timing to get this combo to work at all on the street/strip.
 
Is it an alcohol carb, or a gas unit?
Also, what is the vacuum at idle? is there a secondary power valve or plug? What is the timing curve
 
This problem is 100% convertor. If putting it in gear the vac drops from 10 to 3, you need more convertor.
 
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