im going to run 081 heads on my LO3 with the LT4 production cam in it with 1.5 roller rockers. so it will be about .450 lift. what valve springs should i use?


thanks
bryan

 

Most any of the popular Stock diameter 1.25"/1.26" hi perf replacement springs will work fine. Comp cams 981 Lunati 73943
Crane 99848. All these will drop on without machining the head. If the heads origionally had exhaust rotators and you want to eliminate them you have to shim up the exhaust springs seats to compensate for the difference in installed height. usually requireing a 3 shim stack of .015+.030+.060" to correct the installed height when a normal SBC retainer is used. Set up the springs for a 1.70" to 1.72" installed height.

The last few 305 heads i set up without OEM oil shields or rotators using stock GM retainers required 1 .060" shim on the intakes and the 3 shim .105" stack on each exhaust spring seat.

Comp cams 48pc shim pack # 4753 will have all the shims nessessary to set up your springs for proper installed height.