602/JDR Carb

Have a 602 with 95 Chevy truck manifolds and Lobak mufflers...Bought a JDR Carb came with 73 jets main and secondary , way to rich ...The motor skipped...Went to chassis Dyno gained 40 hp dropped ten jet sizes different, squirter's and power valve....Fuel pressure is good a/f ratio is good a tad lean on idle...Just not running right doesn't pull change a/f mixture screws to fatten up idle and it skips...Guys i race against are running much richer ...Any suggestions would be greatly appreciated..

Sounds like an exhaust issue or weak ignition.

I'll recheck I've checked everything

If you put headers on temporarily, re-jet, and it makes a huge difference you'll know the exhaust is choking it. Testing and or changing the ignition parts might be good to try in case it just can't fire like it needs to.

I'd look at the air filter too.

Did you call John at JDR? He will help you straighten out the problem. My guess is also exhaust restriction or vacuum leak.