BB exhaust manifold question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

cheyenne10 · 03-20-2005, 01:39 AM

I am using a pair of stock exhaust manifolds on 454 BB. These have the flat surface where exhaust mates up to them. Am I supposed to run the exhaust preheat valves (can't remember specific name) on these? I am worried about warmup times and also the need for good gasket from manifold to exhaust pipe. If I remember the preheat flapper extensions have the bevel end for use of the donut style gaskets. I don't want to end up with leaks with lessor gasket on flat surface mate up.

cheyenne10 · 03-20-2005, 04:41 PM

Am I on the right track looking for these pieces or do most people discard them?

JimKshortstep4x4 · 03-21-2005, 08:54 PM

We don't run the heat risors on our trucks. I use a hand die grinder and chamfer the manifold at a 45 degree angle so the doughnut will have a location to pilot in.

Jim

03-20-2005, 01:39 AM	#1
cheyenne10 Senior Member Join Date: Apr 2000 Location: Oregon Posts: 2,512	BB exhaust manifold question I am using a pair of stock exhaust manifolds on 454 BB. These have the flat surface where exhaust mates up to them. Am I supposed to run the exhaust preheat valves (can't remember specific name) on these? I am worried about warmup times and also the need for good gasket from manifold to exhaust pipe. If I remember the preheat flapper extensions have the bevel end for use of the donut style gaskets. I don't want to end up with leaks with lessor gasket on flat surface mate up. __________________ Bob

03-20-2005, 04:41 PM	#2
cheyenne10 Senior Member Join Date: Apr 2000 Location: Oregon Posts: 2,512	Ttt Am I on the right track looking for these pieces or do most people discard them? __________________ Bob

03-21-2005, 08:54 PM	#3
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	We don't run the heat risors on our trucks. I use a hand die grinder and chamfer the manifold at a 45 degree angle so the doughnut will have a location to pilot in. Jim



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