Finally got the Mustang to a track last month. Ran 8.09 at 85. Would not rev over 5800. Every time, it starts misfiring and breaking up at the same rpm point. Does during driving around, revving in tne driveway and at the track. Same issue with all Duraspark and the MSD reinstalled. Carb seems to be working and getting fuel. Sumped tank and Holley mech fuel pump.
This started when I put the AFR 185 heads on last year. I have their standard flat tappet hydraulic style valvesprings, Comp roller rockers, on adjustable studs with guideplates. The Irongt40 heads with Comp 972 springs would go to 6200 anytime. Has a Rhodes LIfters 270 cam with Rhodes lifters, .484 lift.
Would shimming the springs help, or should I just get stronger springs?
This started when I put the AFR 185 heads on last year. I have their standard flat tappet hydraulic style valvesprings, Comp roller rockers, on adjustable studs with guideplates. The Irongt40 heads with Comp 972 springs would go to 6200 anytime. Has a Rhodes LIfters 270 cam with Rhodes lifters, .484 lift.
Would shimming the springs help, or should I just get stronger springs?