i got a 750 holley double pumper. Throttle response is very weak. 60 foot time dropped dramatically. ran 1.72 with 104 vp fuel. dropped last yr to 1.77 with pump gas. This year its at 1.85. I know its not the tires. I left the jets 72/84 in even though I changed to pump gas last year. But why is it effecting this years performace? I rebuilt the carb., I cant figure out what I missed. I have a 355 dart 202 heads 1.6 64cc, Norris 310/320 510/540lift solid cam. yeah, I have a small stall, so I launch at around 2700 rpms. But it still launches the same, just feels a little sluggish on the 60foot. plugs look good. Its just killin me, 4th race Ive been fighting it now. Does anyone have any ideas?

i got a 750 holley double pumper. Throttle response is very weak. 60 foot time dropped dramatically. ran 1.72 with 104 vp fuel. dropped last yr to 1.77 with pump gas. This year its at 1.85. I know its not the tires. I left the jets 72/84 in even though I changed to pump gas last year. But why is it effecting this years performace? I rebuilt the carb., I cant figure out what I missed. I have a 355 dart 202 heads 1.6 64cc, Norris 310/320 510/540lift solid cam. yeah, I have a small stall, so I launch at around 2700 rpms. But it still launches the same, just feels a little sluggish on the 60foot. plugs look good. Its just killin me, 4th race Ive been fighting it now. Does anyone have any ideas?What is your total timing set at?

That has been an issue. 34 at 3400 rpms. But it drags a little. had distributor worked on this year by a highly respected race mechanic. he said 34 degrees at 3400 rpms.

That has been an issue. 34 at 3400 rpms. But it drags a little. had distributor worked on this year by a highly respected race mechanic. he said 34 degrees at 3400 rpms.I would try and have all your timing out by 3,000 or less.

he said my curve starts at 3200 at 23degrees.

your saying, lowering to 3000 rpms will pick up the throttle response?

your saying, lowering to 3000 rpms will pick up the throttle response?It sounds like you are running a distributor with vac. advance.I am saying have all your total timing done by 3,000 r.p.m.'s.I would start around 35 degree's total timing make a pass and see what it does.Advance it a degree at a time until the car starts to slow down.

Thanks. Hey my dad used to do all tuning on the car but he cant do it at all anymore nor really give advice. So I have been reading and going by word of mouth. Thanks.

Think I should down Jet since I went to pump gas?

Think I should down Jet since I went to pump gas?I would find out where stock jetting is on the carb and then drop down 2 jet sizes on both the front and the rear.Make only one change at a time.Make a pass kill it the end pull the plug and if it is black then drop your jet size down.You really want to shoot for light tan.If they are white or gray you have gone down to far in jet size.Also keep in mind that some of the gasoline additives will change the plug color.

70 front 80 rear. I wanted to say that I have a weiand accellerator intake with a 2 inch open spacer. I got the cam specs 3500-7500 range, and the intake was 2500-6500 so I figured the spacer would increase my rpm range a little to offset with the cam.

70 front 80 rear. I wanted to say that I have a weiand accellerator intake with a 2 inch open spacer. I got the cam specs 3500-7500 range, and the intake was 2500-6500 so I figured the spacer would increase my rpm range a little to offset with the cam.Yes,the spacer helps build velocity and it also helps to fool the plenum into thinking it is larger than it really is.

thanks for the info N20!

thanks for the info N20!Sure,I hope I was of some help.