Join Date: Dec 2001
Location: Belleville, Illinois
Thanked 22 Times in 17 Posts
I'm not sure exactly what you're referring to. There's the tube that leads from the exhaust manifold to the automatic choke, the EGR system which passes exhaust gas into the intake manifold, the system that heats the intake manifold by passing exhaust gas under it, and the system that heats intake air by pulling it around the exhaust manifold and into the air cleaner intake snout.
I think the EGR system comes closest to your description. The engine will run just fine without it, but the carburetion might need to be adjusted for best performance. The other systems I mentioned have to do with engine warm-up, so without them it will be a little cold-natured but otherwise run fine.
In a stock engine there are no threaded holes in the EGR system, IIRC, so the P.O. must have tapped the passage, probably with a 1/4" pipe tap, but anything is possible. Just try several things about the right size until you find what fits.