Carb. help

[bowstang]

Recently replaced my 650 dp Holley with 750 Quick fuel main body,metering blocks,Proform trottle plate,holley fuel bowls,110 needle and seats,72/80 jets. Problem is car slowed down and slight hesatation off starting line. IS CARB. TO BIG? 85 Mustang 350 chevy fast burn heads 9.6 comp.,474/510 hyd. roller cam ,GM dual plane intake,HEI,1 5/8 long tube,turbo 350,10" 2500 convertor,410 rear,28 total timing. Also put 660 vac. secondary carb on and went faster than 750.Thanks Steve

[bowstang]

anybody?where's oldhead & honkif parts fall off

[Road Runner Kev]

Hey Steve, I seriously doubt that it's too big, just needs a little tuning. Does it only do it on hard acceleration or does it happen durring easy driving?

[bowstang]

Hey Kev what's up? Only on hard take off,cruises fine and ok on highway!Steve

[Road Runner Kev]

Steve it sounds like it's just too lean. Try going up 2 jet sizes at a time front and rear and watch your trap speed. It should increase. Keep going up in size untill trap speed starts to fall off. Do that first and it should help at the line too. When you get your best trap speed out of it then you can work on the 60' starting line issue. That sounds like it's in the squirter circuit. Try going up a size in squirters front and rear until stumble goes away. If your stumble is real bad do the squirters first but after you get the jets right you might have to play with squirters again. Good luck, Let me know how it works out.

[Gameracing]

.........and try about 34 degrees total timing, carb advice is spot on, though I usually get the bog out with squirters first, then jets, then redo squirters.

[quick77]

I had similar problems with an AED 650 dp on a 400 sbc.
AED used holley style bowl screw white washers on the bottom of the pump squirters, they were too tight a fit around the threads of the squirter screw theads, causing a restriction / delay of the pump shot , maybe something like this is some of your prob.
I found some looser fitting washers, helped alot,also spent the $$ for the hollow acc. pump screws. Bog was gone at this point, I also used the pink acc. pump 3 position cams pri/sec sides of carb, in the #1 hole, like this the pump is discharging fuel the entire time the throttle plate is opening , pri and sec !!
34-36 Degrees total sounds about right, if your running an MSD dist, try the black bushing in the dist. along with a light set of springs.

[adamsvega]

2 things .the stock booster and its feed diam. are smaller than the proform. the type also changes the jet required .
with in the same carb body the straight need most,dogleg middle and anular the least .you need more squirter dia. and squirt volume .
hold the primary throttle open to 2500 rpm and tap the rear squirter and see if it revs = richen up