i am in the process of getting my 502 back together i added roller rockers. anyways the factory valve covers will no longer fit. i am running gil/ mercruiser performance manifolds. i called my speed shop to pick up a set of tall valve covers and they said my exhaust wont clear the larger covers. what do i do?

110351568526 on ebay.... look like they have more clearance... but will they fit bbc gen V. this stuff keeps adding up. its killing me.

Try heavy cork gaskets from Mr Gasket or Fel Pro. They come in several thicknesses. Get you another 1/8 inch at least. Jegs or Summit Racing.

Merc grinds the corners off a couple of the roller rockers used on the HP motors. Looks kind of crude, considering what they charge for motors.
Might want to look for a picture of real Merc HP motors and see if that is your problem.

i think they even had different covers than i did. every locknut hits.... what about those 420 merc valve covers.

You need to grind off the drip tabs on the inside of the valve covers. You may also need to grind off the corners of the roller rocker arms on a couple to clear the baffles at the fill holes. They will fit.

You may also need to break off the drip oilers that hang down from the top underside of the covers. You can snap them off with pliers.

No body said it was going to be easy or cheap !!!!!! Keep smiling and think of all the fun you are going to have when it's all back together.

All the roller rockers I have bought in the past had two in the set that had the corners rounded off. I did not want to mess with grinding tabs off. I gound off one tab to see if it would work, and it would but I still would need to use two gaskets.
I just purchased new valve covers.

Every set of Crane gold rockers I have ever seen in a bb Chevy had those 2 clearenced rockers. Not a big deal. Only takes a little work on a belt sander. Most are cleared more than they have to be. 420 valve covers will fit.They came with Crane rockers from Merc. But you still have to grind the corners on 2 rockers.