69 crossover ports blocking
I have a 66 gto with a motor from a 69 catalina 400. The code on the head is 48 which I believe makes them Ram Air 3 heads. I have been chasing down an issue and finally narrowed it down to an intake leak and finally realized the previous owner had bolted on an edelbrock intake manifold. It has one spot in the middle of the manifold for the exhaust crossover but these particular heads have 4 more "L" shaped holes for what I assume is more exhaust crossover ports. My manifold doesn't have have holds for these and there is nothing more than a gasket covering up that port and the manifold over that. I believe the source of my problem is the exhaust pressure pushing into that gasket and causing an intake leak.
After close to two hours of reading I have read some point mention putting block off plates over that exhaust port. But I haven't head a good thread on what that consists of. Are block off plates you can buy something online or are people just making them out of sheet metal? It in just one pieces that covers all the holes or plates for every single hole?