Just rebuilt my 350 motor on a 79 z28. Everything inside the block is new, little bit of an up sized cam. Problem I'm having is that It looks like all my rocker arms are either shifted a little towards the left, or some towards the right. And one in particular when I crank the motor, the rocker arm wants to move off the center of the Valve towards the end. Even when the motor isen't running and i tighten down the rocker arm, the valve side moves to the left. I'm new with the whole motor rebuilding experience, got my dad and some other techs to help me out. I'm going to try guided rocker arms tomorrow. I don't know if the motor is actually a 79 model 350 because i purchased the car from someone else, and he "said" the motor was rebuilt but, it just looked cleaned up to me. But I had to replace the water pump in it and an alternator and power steering pump. And all the 79 applications were incorrect. Cant remember exactly what i used to make them work. But i don't know what to do, im stumped and was hoping someone could help me out.

 

Did you replace anything in the valvetrain, or just get a new cam?

 

New lifters, i believe the valve springs are new to. Studs are the same tho, i've noticed on the side of the stud there is a notch almost like the rocker arm gets stuck in that stud, and keeps it from going back to the center of the valve. There is also evidence on the side of the block where the push rod has been rubbing, when it pushes itself to the left. But if the guided rocker arm doesnt work i was going to take the heads to the machine shop and put new studs in them to try and see if that works. Oh, and i do know that it's not a original z28 motor, its a 2 bolt main. And i don't even think its a 79 350 either, any chance that could effect the rocker arms?, if they weren't the correct ones?

 

What heads are they, how much lift does the cam have and specifically what lifters did you use, is is a roller cam?

 

Depending on which rocker arms you are using, you may need push rod guides to keep things in place.

 

Exactly my thoughts Pete.

 

are guide plates installed on this?

 

A picture sure would be helpful.
If the hole (slot) where the pushrods pass through the head are small and close to the pushrods, then that is what should be keeping the rockers centered on the valve stems.
But if you have a larger pushrod hole (1987 & newer head) then you need to be using self-centering rocker arms that have a slight recessed area where the valve stems fit into.
I wonder if you have the large hole heads with the conventional flat tip rocker arms? That would explain the large amount of side travel. Otherwise, your rockers shouldn't be able to twist that much at all.

 

Yeah, if he has guide plates or self-aligning rockers he should be good either way. If he wants to he can have the heads machined for guideplates and install them if he doesn't have them already. If he doesn't then I would recommend them for a high lift most definantly.

I've never had a major problem with stud flexing but would it deflect them that much and to the sides?

Orion> You said your stud(s) have a notch in them on the side? Like left to right sides or front to back?

 

Stud flex wouldn't be what he's seeing, especially since it happens with just tapping the engine over. Now, if his studs were loose, pulling out and rocking back and forth, then that's a different story.
But it sure sounds to me like he has a rocker arm/head mis-match issue. That's why a picture or two might tell the whole story.
It's now been a week, and not a peep from the O.P. though!