I have a ZZ4 350/355
power plus intake open plain
rpm heads....202/160
crane hydraulic roller cam
at 50 234/242
adv.duration 296.305........lift.....539/558
demon 750 mechnical secondary
all msd...distributor no vacuun adv

The last 2 days its been runing like crap... I took out all the plugs 5 look real
good.... 3 are all black not wet... i check the carb its good time is initial..12..
and 34...at....3000.....thanks.......Butch

Butch,
do a compression test.
my understanding is max lift is .540.
you may have bent some valves.

david

david max lift on these heads are 575 part#60999 had them on for a year now