[sqzbox]

Originally Posted by chevyrally68

at 65mph tach reads 3000rpm with a stock 10 bolt non posi.

Thats what I run at 65mph with a TH350 and 4:10:1 14 bolt L/S 1 ton dually rear end in my 4x4 and a stock converter. You'd probably be happier with a 2000 stall.

[123pugsy]

Measuring tire diameter is not exactly correct.
Measure from the ground up to the center of the rim and double it.

[jginnovationspedshop]

That's right slippage and the math is spot on , on a NEW tire no miles as it wears the size changes, and a tire grows as you speed goes up just a lil , the front tires are not in play because they are not the drive axle, my figures on my set up is 420ish cubic blown small block chevy with th350 with 3.85 gears and 275/60/15 rear tire at widest tire I can run and at 65mph math says 2985rpm and my tach. Reads about 3100ish so about right , 275 is the width in mm and ratio 60 is the sidewall is 60% of the width of the tire, you can change tires(rear) and change your gearing crazy huh just take top number in the equation that I sent you and divide it by different tire sizes like (26inch 28inch 30inch tire and see how much you rpm changes)

[sqzbox]

Originally Posted by 123pugsy

Measuring tire diameter is not exactly correct.
Measure from the ground up to the center of the rim and double it.

I believe it would be from the center to the top as the bottom would reflect sidewall sag with radial tires. That would only give the tire highth.
One would have to mark the tire and measure the total distance of one revolution on the ground to be exact and even that measurement would change with tire speed to a degree.
In his case, I don't think the tires are as much a problem as the stall speed is higher than the speed rpm he wants to cruise at. So, either change the rear ratio or reduce the stall speed of the converter to reduce slippage at cruise speed. Only problem is if he changes rear end ratio mileage will suffer. Change the stall speed and it will improve. Slippage also builds heat (bad).

[123pugsy]

Not a big deal, but measuring from the ground up is correct.

My wife had a flat tire before and she told me ''its not too bad, its only flat on the bottom.''

[runn141]

get rid of the 3000 stall converter. either get a stock one or one with no more than 2200.

[ericnova72]

Originally Posted by runn141

get rid of the 3000 stall converter. either get a stock one or one with no more than 2200.

No way! The converter he has now is perfect for the job. Go to 2200rpm stall and it will be a slug off the line. Everything he has posted is perfectly NORMAL. He just needs to get used to the feel of a performance converter.

[jginnovationspedshop]

chevy truck conveters like 78-79 from autozone ,,or sum-g2629 12inch chevy converter from 1700-2000rpm $100.08

[jginnovationspedshop]

yep sounds right to me but he is driving the car , i would leave it, but not my car,

[runn141]

Originally Posted by ericnova72

No way! The converter he has now is perfect for the job. Go to 2200rpm stall and it will be a slug off the line. Everything he has posted is perfectly NORMAL. He just needs to get used to the feel of a performance converter.

he doesent have enough motor to need that converter.