SBF HELP

[Ascstang]

I am new to this forum but hopefully someone can give me some suggestions to fix my car. Brief history: it's a 1988 ASC McLaren mustang with a 347 and a powerglide. The car weighs 3200lbs with me in it and has 5.14 gears in the back with a spool. The car runs 6.50's 105 mph with decent air and 10.30's 135mph in the 1/4.

Here's the problem. If we have cool air the car runs deadly consistent and leaves good. If it is warmer and more humid the car stumbles on the initial launch then clears up. Kinda like a quick hiccup. Example two weeks ago it was about 72deg. And ran 6.64 all day. Then the following week it was about 80 deg. And the car lost .08-.10 on the 60ft and was running 6.87.

I understand the car will run slower with warmer more humid air but I need to get rid of the hiccup at the launch of the car. It has a pro systems carb on the car that was built for my setup. I have tried just about everything but I am open to more suggestions. Thanks for your help. Adam

[supernova]

Have you looked at the plugs to see if there is a rich condition in the heat and humid air. In most cases a jet change will fix the problem in the heat. Going down a jet size or two will help. And everything slows down in the heat. The air density quality lessons with heat and homidity thus causing the motor to make less power and needs less fuel to run correctly.

[supernova]

Oh and welcome to Drag Stuff. Lots of good people here.

[Ascstang]

Thanks and yes I have tried that. If I go down on my jet sizes should I also go down on my squirter size? I think I have 40 square right now. And no power valve

[supernova]

I would leave the jets alone and try a smaller squirter. You could try bumping the timing up some and see if that will help.

[supernova]

I would leave the jets alone and try a smaller squirter. You could lesson the accelerator pump hit so it put less fuel in it at the hit. I wouldn't leave it like that but is easy to do to see if it effects it. You could try bumping the timing up some and see if that will help. Just thing to try.

[Ascstang]

Thanks for the tips. I will try them again. I was out most of the year last year with the same issue and thought I fixed it but it had just gotten later in the season and started working better. But hey it doesn't hurt to try. Thanks and I would appreciate any more feedback anyone has. Thanks supernova.

[supernova]

Your welcome!