As the weather warmed up I began having vapor lock issues with the 292 which are getting progressively worse. It's to the point now that I can't drive farther than about 12 or 15 miles before it starts acting up and finally stalls. I have a 500 cfm Edelbrock carb that is practically new and is properly set up, new fuel pump and fuel filter. I suspect the exhaust passage in the intake is causing the gas to boil out of the float chamber. I have a 1" phenolic spacer coming, but I was wondering if it would be advantageous to block off the exhaust passage in the intake? Seems like eliminating the source of the heat would be the best option. Can I just loosen the manifold enough to slip a couple of pieces of thin stainless shim stock in between the heads and the manifold? If so, do they go between the manifold and gasket or between the heads and the gasket?