1970 340 intake manifold stock thickness

[jawbone]

Does anyone recall what this number would be. My cast iron intake is ready for assembly. I could only measure a .006 gap in one place so was going with the Superformance .031 but would like to know if my margins are too narrow. Gasket compression is advertised at .005 Jeff

 

[furrystump]

So wrapping my head around the question. Stock uncut intake? Heads milled? Block decked? My block deck was cleaned up, my heads were cleaned up. Intake uncut, stock 68 340 intake, cross over blocked. I use felpro 1213. No issues. I do use a very small film of rtv around the openings. I made finished plywood boards to clamp and “glue” them to the intake first using the the small film of rtv. Let it dry. If you use too much it will squeeze out and stick to the board. You can cover the board in masking tape, just in case. Then small film around the ports and water passages and on it goes. China walls my situation is not the same as stock, but in the past I never used the cork gaskets. Rtv. I don’t like vacuum/water leaks! I does take some effort to get the intake off!

 

[jawbone]

So wrapping my head around the question. Stock uncut intake? Heads milled? Block decked? My block deck was cleaned up, my heads were cleaned up. Intake uncut, stock 68 340 intake, cross over blocked. I use felpro 1213. No issues. I do use a very small film of rtv around the openings. I made finished plywood boards to clamp and “glue” them to the intake first using the the small film of rtv. Let it dry. If you use too much it will squeeze out and stick to the board. You can cover the board in masking tape, just in case. Then small film around the ports and water passages and on it goes. China walls my situation is not the same as stock, but in the past I never used the cork gaskets. Rtv. I don’t like vacuum/water leaks! I does take some effort to get the intake off!

I had nothing but a deck and head cleanup as well. Your felpro 1213 is advertised at .060 thick. Hope I'm not trying to put one on that's too thin.

 

[furrystump]

It doesn’t have a cross over hole. I never had it blow through the gasket, but many years ago I made a slight recess in the intake and tape a small square of sheet metal to help support it. My cross over on the intake is milled off.

 

[jawbone]

It doesn’t have a cross over hole. I never had it blow through the gasket, but many years ago I made a slight recess in the intake and tape a small square of sheet metal to help support it. My cross over on the intake is milled off.

I made short alignment studs to hold the gasket in place and help guide me during install. They only stick up slightly above gasket. Tested it and it works. As for current gasket may go with a thicker one with sealant around openings.