I recently had a valve job done on my stock iron 440 heads. The engine is mildly modified with ‘adjustable’ Crane rocker arms, and flat tappet hydraulic lifters. So, with the heads torqued (70 ft/lb), rocker shafts torqued (25 ft/lb), and rods installed, I started to set the rockers for zero lash and final 3/4 turn adjustment. BTW, nothing changed. Same lifters, same rods, same valves, same cam, etc. Just reseat the valves, with new seals, and guides.

As I work my way around, I’m finding that any lifter sitting on the apex of the cam lobe, the push rod is already so tight against the rocker arm that setting it for zero lash is impossible, let alone another 3/4 turn. Moreover, the rocker adjusting nut is completely 'backed' off. I hadn’t removed the lifters, so they may still be filled with oil (if that makes a difference).

Should I set the zero lash with the lifter(s) resting on the 'base' of the cam lobe with the push rod spinning freely? If I use this method, it would seem that when the cam rotates, and the lifter(s) eventually rest on the apex of the lobe, I could end up bending a rod. All the youtube videos show adjusting for zero lash, regardless of where the lifter is sitting on the cam lobe, and then making a final 1/2 or 3/4 turn. I dunno'. I never done this before, and wanted to check in with the experts before I start bending rods and valves. Any education would be greatly appreciated. Thank you.

 

Do your adjustment with the lifter on the base circle of the cam.

 

Thank you, Dan. Will do.

 

Agreed... Base of the cam lobe....
Zero lash = all the clearance taken up in the "Up and down" movement of the push rod.... Not the spinning of the push rod....
as soon as all the push rod and rock movement slack is taken up... That is considered zero lash.. Lifter plunger must remain at the top at its rest position..

 

Thank you RacerHog for the explanation!