I was mocking up my valve cover fit on my engine last night. I would like to use a set of the factory-style cast aluminum valve covers like the Gen VI motors came with, because they have the factory baffles for the breathers. I thought for sure I would have enough clearance with the raised VC rails on the AFR's, but I am getting interference with the poly locks on the #8 and #1 intake rockers. I am wondering if a set of shorter poly locks will give me the clearance I need. Has anyone else run into this problem, and were you able to get it to work.

FWIW, the best I can tell, the HP 500 valve covers appear to be exactly the same dimensions as the stock Gen VI valve covers. Correct me if I am wrong - are they deeper than the GM ones?

are you sure the polylocks are hitting the valvecover,a crane style rocker arm will hit if not modified.

Mike's right. I think its the #1 and #8 intake rocker that needs to be grinded for clearance for the bolt boss in the valve cover? Also, how much clearance is it you need? they do make thicker valve cover gaskets.

Mike, it was definitely the lock hitting - it fit fine if I removed it. However, I won't know for sure until my pushrods arrive and I can adjust the valves and run it through a few rotations.

I saw that Jegs sells a set of 4 Scorpion brand poly locks that are shorter than the standard ones - .975" instead of the 1.2" on the standard ones. I may order a set of these and see if they give the necessary clearance. Just wondering if anyone else had gone down the same path.

Has anyone compared a set of HP 500 covers next to the GM ones? They sure look the same, and Merc was running the Crane Gold full rollers on their engines.

MT, the Scorpion rockers I am running are already relieved in this area for clearance.

cool. I'd probably get the correct pushrods in, and adjust valves. Then see what your poly locks look like. As in, where the set screw ends up. Then go from there.

If you are using the new style covers that have an o-ring gasket, they will leak unless you use a mark IV gasket. The old school gasket will also give more clearance. Felpro makes a rubber encapsulated steel gasket that works real well.

Yup. They make gaskets from .094 to .312 thick. My buddy used the o-ring style newer valve covers, with the oring, they leaked. He switched to the standard old school gaskets like Kvogt said, and no more leaks.

Choose your thickness on the left column
http://www.summitracing.com/search/p...-size/7-4l-454

The hp 500 valve covers have the tabs milled out of them, and the corners of the rockers are clearanced. I had one set just touch the locks on a pair of hp500's. it was a head gasket valve job the guy needed back ASAP and I regretfully didn't inspect rocker arm geometry to see what was causing the issue. The exhaust valves are longer in the afr heads aren't they?

That is correct.