[25stevem]

Push rods that have been run with other rockers can take on a ware pattern and should not be reused with different or new rockers without very close inspection.

I would pull off all the rockers and lay a straight edge to span all the valve tops and check to see if seat erosion is taking place and sinking certain valves deeper up into the head.

If you adjust all the valves zero lash when there known to be on the base circle of the cam and then they get tight and hold a valve open then either like I posted , the valves are receding, or you might have some lifters that have popped out there plunged retaining clip, in which case you will never get them adjusted right.

[PAUL K]

Originally Posted by GTOGEORGE

Nuts are locking and they are not getting loose.


GTO George

George are you adjusting them while the motor is running? It sounds like there might be run out on the roller tip causing them to tighten and loosen while they are running or bent pushrods. Also make sure the rocker studs are tight.

[Joe's Garage]

Some of that grit could be getting through the oil system and into your hydraulic lifters and causing them to get hung-up. Then the backfiring.

On a second thought, it could just be a bad set of hydraulic lifters that are sticking at different heights and taking the valves out of adjustment.

Thinking outside the box a little.....

[Tim Corcoran]

What lifters are you using?

[77 TRASHCAN]

I’d put a magnetic drain plug in that engine, if you don’t already have one...

[dataway]

If it's only running for short times ... rocker balls could be galling which would close clearances ... then wearing off the mess the galling made and gaining clearance, then you tighten them again, they gall again and get tighter, then wear off the mess and loosen up again.

Pull off the worst offender and look at the bottom of the ball, and the socket on the rocker. The OEM stamped rockers if taken care of would have mirror finish on them.

I'd definitely be running valve cover drippers with those rockers.

I had a brand new set given to me, compared their fit and finish to used OEM rockers, boxed up the rollers and threw them in the garbage. Mine were Comp Cam I think. I messed with them a while ... they can be improved quite a bit by lapping the ball washers into the rocker sockets with a drill ... but figured the overall quality wasn't going to be there so I didn't use them.

If you use the OEM rockers ... polish the rocker valve stem contact area on a metal buffing wheel if you have one, right to a mirror finish. Might not do any good, but I figure it makes them slide across the valve stem a bit easier.

[GTOGEORGE]

Thanks!


GTO George

[Kenth]

If running 20w50 try 10w30 engine oil.