Hey guys, quick ? for everyone. I'm working on an 87' 357 Formula with an obstruction in one of the risers, making the engine run hot. I have the gaskets on order that mate the riser to the stainless stack, but am having trouble finding the manifold-to-riser gaskets. These are the big exhaust manifolds and risers that the 420's ran, the ones where the riser has 6 bolts instead of 4 securing it to the manifold. Does anybody have any leads on locating 4 of these? They are listed as NLA. I would like to split the manifold and riser apart, flush it, re-surface the mating surfaces, and re-gasket. I've got a potential lead from a dealer in Texas that may have 4 that I will check out tomorrow, but beyond that, not too much else. I'f you guys know where they are, please let me know. I would rather buy them, then have to make them myself! Thank You, Nick.

Those things are trouble. You can make your own gasket but they discontinued that whole set up for good reason. If they are not clogging up then they are weeping in to the motor. I suggest you budget for new exhaust before you lose a motor over it.

Mercman is right on the money. Those manifolds caused a lot of problems. Merc swapped them out with Gils.

bought some from CP performance 2 years ago, they had plenty.

You can make the other gaskets for the riser. you will need to find some proper rubber EPDM with cloth inserted(grainger) 3/32 thick I believe. Get the correct hole punch and a razor knife and your done. Using cheap rubber or the wrong thickness will result in leaks very quickly.