Converter Slippage at top end

[Dan Fahey]

Originally Posted by ss3011

4L60 has a 3.06 first gear and a huge ratio change from 1gear to 2nd gear . Might want to checkout the Sonnax gearset that reduces 1st gear into the 2.8 range . Are you planning on using 4th gear ?
Back in the mid 80's I ran a Olds Cutlass with a 307 and a 200-4R with a 2.74 first gear , 5.57 rearend gear , and a 28" bias tire . The problem with all that ratio is the engine can't rev up that fast . Much of the engine power was trying to accelerate the drivetrain , and not the car . Ran better with a 5.38 ratio , and swapped in a different overdrive ratio (.72) and that helped a bunch . Converter clutch was worth 2 mph !

Depending on what I do...
5.38 will work with existing PS cam with OD or Locking Yank 4400PT..
In fact would be good with Stocker Cam holding rpm below 7000rpm. Preferably 6800 rpm with existing 28 inch slick.

Want keep the rpm 7000 or under.
Speaking to Don Compolito their J/SA crosses at 7500 rpm
Car would need better rods for that rpm.