femtnmax
Well-Known Member
Building a 383/432 stroker for street use, probably 6000 rpm max. Have a NIB Crower hyd flat tappet cam. Plan is to break the cam in with the oem valve springs and stamped rocker arms. Then switch to Comp 911 springs and Crane 1.6 iron rocker arms.
Checked the rocker ratio with .080 lash caps on valve stems result is .542/.547 lift at the valve so actual ratio is 1.7. The lash caps were added to prevent scrubbing of the rocker/valve stem contact near/at full lift. Adding the lash caps optimized the pushrod angle vs the rocker arm adjuster, which gave the extra valve lift. Heads are 906 with Ferrea valves.
The higher lift is no problem, my old Ford FE428 has 1.76 rockers from the factory. So I compared seat, .05 duration, and max valve lift of the Crower cam vs Lunati hyd voodoo for FE428 part #62003.
Intake seat duration: Crower=267, Voodoo=268
.05 duration: Crower=226 (w/ 1.7 rocker), Voodoo=227
Intake lift: Crower=.542 measured, Voodoo=.552 (w/ 1.73 rocker for FE390)
Valve spring seat load for Voodoo is 120 lb, open load=309 lb at .552 lift
Valve spring seat load for Comp 911 spring is 122 lb, open load=322 lb at .542 lift.
At max valve lift the valve spring retainers clear the valve seals by 0.10 inch (I cut 0.1 off the guide height).
Looking at the seat vs .05 cam lobe intensity the Crower is 267-226=41 degrees. The Voodoo is 268-227=41 degrees. Both initial rates of lift have the same intensity.
This looks like it will work to me. BUT .what have I missed? Do YOU see any problems with the idea?
Checked the rocker ratio with .080 lash caps on valve stems result is .542/.547 lift at the valve so actual ratio is 1.7. The lash caps were added to prevent scrubbing of the rocker/valve stem contact near/at full lift. Adding the lash caps optimized the pushrod angle vs the rocker arm adjuster, which gave the extra valve lift. Heads are 906 with Ferrea valves.
The higher lift is no problem, my old Ford FE428 has 1.76 rockers from the factory. So I compared seat, .05 duration, and max valve lift of the Crower cam vs Lunati hyd voodoo for FE428 part #62003.
Intake seat duration: Crower=267, Voodoo=268
.05 duration: Crower=226 (w/ 1.7 rocker), Voodoo=227
Intake lift: Crower=.542 measured, Voodoo=.552 (w/ 1.73 rocker for FE390)
Valve spring seat load for Voodoo is 120 lb, open load=309 lb at .552 lift
Valve spring seat load for Comp 911 spring is 122 lb, open load=322 lb at .542 lift.
At max valve lift the valve spring retainers clear the valve seals by 0.10 inch (I cut 0.1 off the guide height).
Looking at the seat vs .05 cam lobe intensity the Crower is 267-226=41 degrees. The Voodoo is 268-227=41 degrees. Both initial rates of lift have the same intensity.
This looks like it will work to me. BUT .what have I missed? Do YOU see any problems with the idea?
