Timing chain play? Ponchos were the original notorious nylon cam gear tooth shredding specials, but since the cams been swapped, that should be less likely........maybe
the cam is installed wrong or is a POS cheap cam. My one time friend long ago bought a J.C.Whitney special for His Poncho 400, His Dad(Who taught Me how to shrink
sheetmetal after I had it stretched out welding) did a nice job of re-doing the car Electric Blue Poly white vinyl roof '73 Catalina Coupe, beautiful car. He put the stick in
it and it didn't idle for s#*t, and wouldn't get out of it's own way. Looking all over for leaks and this & that, called Me, I didn't find anything wrong either so I said "yank
it". Took it to My place and set up some V-blocks and a dial gauge,.........2 of the intake lobes would stop .020" short of the base circle for an extra like 40deg!!
Not sayin' it is, but bad cam or cam timing/install certainly, a flat exhaust lobe will do this exact thing.....sounds just like half of the 305 Chebbies when that occured.
the cam is installed wrong or is a POS cheap cam. My one time friend long ago bought a J.C.Whitney special for His Poncho 400, His Dad(Who taught Me how to shrink
sheetmetal after I had it stretched out welding) did a nice job of re-doing the car Electric Blue Poly white vinyl roof '73 Catalina Coupe, beautiful car. He put the stick in
it and it didn't idle for s#*t, and wouldn't get out of it's own way. Looking all over for leaks and this & that, called Me, I didn't find anything wrong either so I said "yank
it". Took it to My place and set up some V-blocks and a dial gauge,.........2 of the intake lobes would stop .020" short of the base circle for an extra like 40deg!!
Not sayin' it is, but bad cam or cam timing/install certainly, a flat exhaust lobe will do this exact thing.....sounds just like half of the 305 Chebbies when that occured.