I've got a basicly stock 1991, 454 Mag. I'm swapping cams this winter, but I'm keeping the stock aluminum hight rise intake. Would the be any benifit to blocking off the exhaust passage that goes under intake plenum? How would you do this?

BTW, the stock Winters/GM intake looks an awefully lot like the Weiand Team G dual plane intake.

Oh yea, keep that heat away from the intake manifold, I use 2 square pieces of 10 gauge stainless steel that fits just inside the square holes in the manifold gasket and then use ultrablack to hold them in place. This keeps exhaust gasses from heating the intake manifold. I also use a shield tray under the manifold to keep oil flung from the crank and cam from hitting the bottom of the manifold. On the Mark 4 the GM number for the tray is 12555320.

Thanks, that's what I was thinking. I've already got the tray under the intake.

Yep, since you ain't dealing with the spring type choke, don't need no heat there.

You can also purchase intake manifold gaskets that have a metal block off plate allready installed at any good Hi- Performance Shop.

Did it for years on drag cars (before Dart intakes came along) the exhaust heat was to activate/deactivate the choke, on a dyno it was worth about 4hp back in the stone ages..

I think that the new Felpro gaskets come with those blocked off.

Jon

If you get the right part number!

I used the Felpro but, I took the intake off a year later and the gasket had deteriorated. I think I would back it up with the stainless.

Ive even had 18 gauge stainless burn out in a year. If you can cut it with tin snips, its not heavy enough. Thats why I went with the 10 gauge (nearly 1/8").