mech flat tappet to mech roller...

[Guest suprstock]

I have .540 .560 lift flat tappet standard base circle cam in GM 383 ci .Would you think a roller cam with the same lift, same standard base circle, would still clear rods ? 6'' rpm I beam rods cap screw arp bolts...

[grumpyvette]

the LSA has an effect on clearance issues and a roller cam generally holds the valves open longer and opens them faster so it will require verifying the clearances during assembly, even with similar lift on the valves(don,t forget to check both the connecting rod to cam clearance, and piston to valve clearance)

Edited December 28, 2009 by grumpyvette

[dr_hunt]

I have .540 .560 lift flat tappet standard base circle cam in GM 383 ci .Would you think a roller cam with the same lift, same standard base circle, would still clear rods ? 6'' rpm I beam rods cap screw arp bolts...

 

If your running the same rods now, yes, otherwise probably. But why would you run the same specs on a roller cam and change cams, add expense, etc?

 

#2 and #5 cyls are the ones to check for clearance. Just about any machine shop has a jig to profile the top of the rod bolt area for clearance with the cam or check aftermarket rods to make sure you won't have issues, so I suggest if that is the route your taking have them checked. Typically I like to see about .020 or more between the rod and lobe on stroker motors. The cam turns half the distance of the crank so cam profiles, unless drastically bigger, don't have much of an effect on clearance. Neither does chain slack IMO.

Edited December 28, 2009 by dr_hunt