Prototype 304 V8 engine

My engine went in for rebuilding, and the fellow said this was a prototype engine. While still being a 304, the shape of the heads and all had some differences that produced a little more horsepower. He also mentioned some brass plugs. Is he referring to freeze plugs? Has anyone ever heard of this? It just doesn't make sense to me since these were dropped into a million AMCs. As an aside, has anyone ever heard of a CJ-9?

 

Maybe he meant plugging up the smog stuff on the exhaust manifolds. We pulled out all the smog tubes and stuff out of the exhaust manifolds on my 304 and drilled and tapped the holes and plugged them with brass plugs. A prototype engine? Wow. Let us know what you find out.

 

One of the AMC guys think maybe the guy meant it was one where the valves could be tuned to application instead of the later style one size fits all zero clearance. He said he'd prefer the tunable one himself. Otherwise he mentioned that exhaust ports changed to a 'dogleg' style.

 

Do you have the dogleg heads? Do you know what year your engine was made? If you have a 304 with rectangular-port heads it's either an extremely rare factory version or someone swapped the heads an intake from a 290.

 

I don't know. The Jeep and engine are about an hour away, but I'm gathering info to ask him more detailed questions. But he said its different than 304s he's seen in the past. I do know the history of the Jeep and the PO did not alter the engine.