The Stovebolt Site Forums The Shop Area Engine Shop 216 intake/exhaust manifold problem

Hey guys,
I have a 1951 Chevy 3604 with the original 216 engine. This winter I stripped everything off, cleaned, and painted it. One problem, two of the ports on the exhaust manifold were rather rusty and are not perfectly flush with the engine block and therefore she runs quite loud. I have tried two new gaskets with manifold sealer. The second time, it sounded great, but after a few days of driving, it began to leak again. Should I try and get the surfaces milled, buy a another used manifold (may have the same problem), or are there new manifolds that I can use without changing the carburetor which is a brand new, out of the original box, 1949-52 Carter Y-F? I would appreciate your guys' suggestions. Jeff

if you have an automotive machine shop around close by I would have them mill them together. Then use new gasket and bolts.

Wada - You might try this first. Loosen the bolts that hold the intake and exhaust manifolds to the block, then loosed tne hear-riser bolts (they hold the 2 manifolds together) so that they can slide around a little. Then retighten the manifold-to-block bolts. Then retighten the heat riser bolts. Sometimes the heat-riser bolts can hold the ports off-center a little.

I can't loosen the heat riser bolts. I tried when I took the manifolds off originally. I also used new bolts. I think I'm going to have to find a machine shop. Thanks for the suggestions. Jeff

Jeff,

The studs and bolts holding the two manifolds together are notoriously rusty/busty dudes. Lots of heat and penetrant along with some careful wiggling and loosening will usually get them loose. There is a gasket between the two manifolds that should be replaced when you are putting all this effort into this project.

My advice would be to do whatever it takes to get the two apart, clean up that sealing surface well and install a new gasket. Clean the mating surfaces with a file and make sure the bolts are not rotted off from exhaust gases. Reassemble both manifolds when they are clamped to the head and tighten the bolts that mate the two.

After all this is aligned and tight, take them to the automotive machine shop and have them milled as a pair...don't move them again, and make sure the machinist has done this before and knows what the desired outcome is suppose to be.

This is a real simple job if it is done properly...it is frustrating and a waste of time and moola if it is done wrong...do it right!

Don't forget that the alignment rings might have to ground down to allow the manifolds to mate properly if gobs of material is taken off at the machine shop. Lots of folks recommend replacing the two outboard alignment pins with threaded studs to help pull the ends of the assembly snug to the head. Sorry for the extended novel!

Stuart