How close are the springs to coil bind at max lift? Also retainers may be hitting tops of guides.
I saw this happen once with Rhodes lifters, engine would idle all day long soon as it was revved up cam key would shear off. Not a bent pushrod but maybe pushrods are the "fuse" this time.
Are you using the correct lifter and pushrod combination?
Seems to me the Vortec big blocks use different lifter & different pushrod length than the earlier gen 4 big blocks.
Last edited by Greg Latvala; 10-21-2006 at 03:57 PM.