where a convertor holds against a foot brake is meaningless
Many factors at play, such as how good are your brakes, and many other things. Its zero factor, but i guarantee that 10 inch convertor is killing a good bit of ET. Bet my life on it.
The many cars i have owned and raced i have virtually never seen a difference in 60 foot by leaving at different RPM’s
My current car has 8 inch 5,000 stall convertor
I can foot brake it to 1800,2,000, 2500 or really push my luck and hold it to 3,000 hoping it doesnt roll in the beams and it 60 foots within a hundredth any of those ways. Have played with the 3000 trying to cut a better light on a footbrake pro tree deal i only do once a year( won it last year..lol)
In fact, if the convertor is correct for the car, it will generally 60 foot the same off the foot or a transbrake
I used to have a stroker 9 sec Duster. A Points series i raced in 7 or 8 times a year for years with it had pro tree index races and a footbrake only bracket race. I raced in both on the same night. 1.34/1.35 consistently
I would leave off the transbrake with the chip set at usually 4100-4200, running the pro tree 10 flat index, and leave at 2,000 off the foot in the footbrake bracket race and the car 60 footed and ET’ed identically same each way. Same night, same track
Get a good 8 inch convertor when you get the combo sorted out, leave at a comfortable spot on the tach, to be consistent( which is why i almost anyways leave at 2,000) easy to read the tach needle, and the car is “ relaxed” at 2000 dont have to worry about slipping in the beams.
launch rpm can be moved around to help you if you are having problems hitting the tree, but i prefer changing the car around and leaving the launch rpm alone.... front tire pressure, etc.
did you install those heads right out of the box and use the springs they came with?
