Just picked up a 79 shorty 5 spd, interior a bit rough as you might imagine, but no real rust (win). 20R with a Weber and what sounds like a blown exhaust mani gasket. Been a long time since I’ve done any serious wrenching on a vehicle (had an 81 LUV a lifetime ago), looking forward to this art project.
Welcome. If you’re running a cast iron manifold check for cracks between #2 and #3 exhaust ports. Very common on the old 20R. Apparently, they had a factory sheet metal heat shield over that area at one point that caused this to happen.
Thanks for the info Fred. Pulled the heat shield off and found that 3 of the 7 studs holding the manifold on were MIA. Replaced them and the gasket (blown out all over the place) and now it’s as quiet as a mouse up front.