Do I need special valve covers for the LT4 heads with Roller rockers? I can't get the covers to go all the way down, it seems as if the springs are too big or the rockers are too big. Can't really see inside when I put the cover over it.
they do look very pretty though,

Didi you take all the metal out of the bottom of the valve covers. I had to on mine to clear the rockers. I basically used some cutting wheels to take all the metal out. Now I have no clearance problems. But also GM does make LT4 valve cobvers here is a link:

http://www2.hawaii.edu/~wilsonch/lt4valvecover.htm

stock stamped steel covers won't fit unless you trim out the insides with the magnum pro rocker arms. the fitment problem isn't with the heads but the rockers. either get some aftermarket covers or some different rocker arms.

Thanks,
I'll be cutting one pair of my covers this week, just have to decide which set I want to use.

What about using the plates GM and Trick Flow make that allow you to use perimeter bolt valve covers on center bolt heads? In my opinion this would be the best long term solution. There is just such a better selection of tall perimeter bolt covers out there.

How much are these plates, and do you have part numbers?

Hopefully these plate don't raise the valve cover much because you still have to dimple one of the VCs to clear the alternator.

I had looked into using the conversion from center bolt to perimiter bolt. It will raise the valve cover approx about 1/4 inch to 1/2 inch. The valve covers will also be taller so a bigger dimple will have to be made in them, but your valve cover selection will be much better than now.

The problem isn't the rockers, it's the poly-lock nuts on them. They're usually about 1/4" too tall to go under a set of stock valve covers. The adapters might cure it or they might not, every individual head is different, you'd just have to buy some and see.

I notice you don't have either guide slots in the heads, or guide plates... I hope those are self-aligning rockers. Otherwise you've got a problem.

RB83L69, i beg to differ. i used those same rocker arms on a set of vortec heads and the supports that run inside the stock valvecovers did not fit between the body of the rockerarms. that is why the crane race golds are touted as self-aligning NARROW body rocker arms. the pro-magnums have a wider body and don't fit with unmodified stock valve covers. the poly locks fit fine.

PN 24502540 from Pace Performance. Price is $154.

They are non-self aligning rockers. I put one guide plate on friday, going to put the rest of them on in the next half hour or so.

I cut the valve cover supports and the tubes which the center bolts go in off. Then my pro magnums fit fine. They will be noticably louder than if you used the vette valve covers though.
Kory

I didnt have any problems with my valve covers, and I'm using Polylocks as well. go figure.