The Stovebolt Site Forums The Shop Area Engine Shop 292 exhaust manifold leak ???

I have a 1970 C50 with a 292, some where there is a exhaust leak at the manifold, thought it was the doughnut so I replaced it ( was leaking there) but it is still loud. I know that they were prone to cracking, but I can only find 1 hair line crack Definitely not big enough to make this noise. gasket at the head, and where the two manifolds go together look ok. It is hard to see the backside are they prone to cracking there? also will a manifold off a pickup fit?

The 292,s are very troublesome with exhaust manifold leaks when used on heavier then 1/2-3/4 ton trucks. It is probably leaking between the manifolds where the intake & exhaust bolt together. It probably has the 2 1/2 in outlet manifold that the outlet points straight down. The light duty manifolds won,t fit. You might check with a GM truck parts dealer & see if a new one is available, although I dought it. If you take them apart it,s very likely you will havev to replace it. They run extremly hot.

I have seen new old stock for sale on Ebay. Sometimes good used ones. They do pop up from time to time. I would use cast iron headers from Stovebolt, or Fentons. That will stop the leak and help out with the mpgs and a bit more power. I would have it y'd into a 3" exhaust pipe. It will be quiet yet breathe very well. Just an idea. You can go to Kansas Kustoms and they take your old manifold am=md make a split header out of them with dual outlets. Its not real expensive but a neat way to go. Otherwise it will get worse. I hope this helps. Henry

i've gone thru 3 exhaust manifolds on my '65 sub.w/292 in the almost 40 years i've owned it. I found the problem to be they warp in the back, of course where its hard to see. my truck usually runs cool and i was surprised to find the manifolds had warped. the first two just warped over a period of 10-12 years, the third happened quicker but i was using the original radiator which had a few pinhole leaks, in the arizona desert in summer. if you pull the manifolds you probably will find some evidence of exhasut, like soot or discoloring. torquing the manifolds in the proper sequence to proper torque as listed by chevrolet helps if the manifold is not too warped, double gasketing helped for awhile but bolts seem to work loose fairly quick ,requiring constant retorqueing . i got repalcements at the junkyard from pickups.

'''''''''You can go to Kansas Kustoms and they take your old manifold am=md make a split header out of them with dual outlets. Its not real expensive but a neat way to go.'''''''''


I have heard recently that KK does NOT do this any more