Holley Dp Carb Issues

[JOHNNY MOPAR]

just need some help with 750 procomp double pumper carb have trouble with hesitation stumbling off the line and pops through carby wich usually means too lean carby is on a 360 alloy heads 509 cam 10.01 comp 3500 stall 3.7;1 gears car has run 13.0 @ 108 mph have jetted up and down currently running 73's front and rear , 4.5 power valve in front , 6.5 rear 31 squirter front , 28 rear , running pro comp dissy not sure what timing at distributor , has about 15 degrees advance at the crank , car idles rich burns eyes in shed etc , mixture screws are out 1 turn seems to give best idle car ran 108 mph with 830 annular seemed too big have not run with the 750 as yet has similar top end power ? . . .

 

[moper]

I would pull the rear PV and plug it. Go up to 82s in the secondary and put a .31 squirtor there. Check your idle vacuum in gear. My guess is you should have a 2.5 PV in the front as that cam usually idles around 3-5" in gear with low static compression. If the carb has a 30cc acc pump in the front use the .028 squirtor in the front. If it's got .050ccs then keep the .031. That's where I'd start.

 

[wish4hemi]

When I had that trouble with my Demon, it turned out to be because of timing and mixture screws. I didn't have enough initial timing and mixture screws were in too far. A few simple adjustments and it takes off really well now. Your initial timing should probably be somewhere around 16-18 initial and 34-36 total, all in by 2,500. Those are pretty common numbers for small block guys.

 

[ramcharger]

I agree, I don't think you have enough initial timing for that cam. Let us know how timing you have at idle with the vacuum advance disconnected. This needs to be dealt with before carb tuning can be done.

 

[crackedback]

Start it up and keep dialing in advance until the engine stop picking up RPM.

Dial some in, if idle picks up, readjust the idle, then dial in some more until it doesn't pick up.

You can set it with a vacuum gauge or do the max amount until it kicks back on the starter or doesn't run on when shut off.

I bet you won't see much difference between the annular and the proform. They both wet flow about the same is my guess.

 

[JOHNNY MOPAR]

I would pull the rear PV and plug it. Go up to 82s in the secondary and put a .31 squirtor there. Check your idle vacuum in gear. My guess is you should have a 2.5 PV in the front as that cam usually idles around 3-5" in gear with low static compression. If the carb has a 30cc acc pump in the front use the .028 squirtor in the front. If it's got .050ccs then keep the .031. That's where I'd start.

cheers thanks moper will give it a try on the weekend will change that front power valve to a 2.5 as car does idle rough

 

[JOHNNY MOPAR]

I would pull the rear PV and plug it. Go up to 82s in the secondary and put a .31 squirtor there. Check your idle vacuum in gear. My guess is you should have a 2.5 PV in the front as that cam usually idles around 3-5" in gear with low static compression. If the carb has a 30cc acc pump in the front use the .028 squirtor in the front. If it's got .050ccs then keep the .031. That's where I'd start.

I agree, I don't think you have enough initial timing for that cam. Let us know how timing you have at idle with the vacuum advance disconnected. This needs to be dealt with before carb tuning can be done.

thanks ramcharger vac advance is plugged all the time , so run the engine and keep advancing dissy till revs start too drop off , then back it up a bit ?

 

[JoeDust451]

No, keep adv. untill MPH drops off, go in 2* increments, then when MPH slows, go back to the last setting, with that cam, you really need to have the dizzy recurved. with int. around 20-22* & 34-36* total all in around 22-2400 RPM.

If your timing isn't right, you'll be jacking with the carb till the cows come home & never get it to run right. Unless of coarse you have a farm, then the cows will already be home lol. :-D

 

[1wild&crazyguy]

1st when you run 2 power valves they need to be the same prim/secondary.

Get a vacuum gauge and go 2 inch lower than reading@ idle in gear.
If you have to, jam the PV at the spring with a small screw to keep it closed to get the Idle mixture correct to do the in gear setting.

That big of a convertor won't/shouldn't bog it down that much in gear, and will probably end up needing either regular old red cam/28-31shooter or 34-37shooter and orange cam, but hey who knows.

You just have to play with and know to tell weather you're going in the right direction, and why it worked.