not a 57 but asking anyway

[4thgen57]

I have been helping a friend build a drag car. 97 mustang with stock 4.6l block. PI heads with bigger intake valves and cams. converted to carb with a 650 demon, running factory 5 speed trans. finally got it to the track Thursday and again today. launches really hard but then falls on its face. he holds the throttle down and it works through it. running 13.3s at 101 mph. weve tried adjusting timing and jetting up and down. still doing the same thing. any advice is welcomed.
thanks
Chris

[4thgen57]

here is a picture so some people wont complain!

[canadian_ranchero]

what is your fuel presser at speed?

[4thgen57]

Running a holley red pump. 5.5 to 6.5 psi.

[JPotter57]

Holley blue minimum on my stuff...I'm now running holley black pump on my 351c Ranger drag truck.  I'm curious..why did you change to carb?  I think it's cool but there are a bunch that will swear you're going backward.

[rmk57]

Fuel slosh in the tank or carburetor? If it's a vacuum secondary carb it could be opening the secondaries too soon causing a bog.

[4thgen57]

We are feeling stupid right now! Had a stock rear end in the car. thought they were 3.30 to 3.50 gears. took cover off today and discovered they are only 2.73s!!!! ordered a set of 4.10s should help a lot. Also gonna try to tighten up the posi unit. clutches were burnt and gone.

Mechanical secondaries. I tried to talk him into a blue pump but didn't want the expence of running a return line and regulator.  We really just like the idea of running carb over EFI. By the time you buy throttle body and injectors and a better intake you can convert to carb and have more adjustments in our opinion.

[JPotter57]

Understand all that...that's why I haven't changed over to EFI....

[4thgen57]

Swapped the 2.73s for some 4.33s, Ran 12.34 at 107 yanking the left front 6 inches in the air!!! Think we found the problem!