Red Hot Exhaust Manifolds!

[earlroots]

1985 chevy G20 5.0L 4bbl quadrajet 3 spd trans.
ok the thing bogs under load and pops and exhaust comes out the carb. i did plugs wires cap rotor wires and fuel filter. then drove it with the doghouse off and noticed the top of the Y pipe and both manifolds getting cherry red hot. so i figured it was a plugged cat. replaced the cat and the problem is still there. i cant check the timing because when i unplug the 4 wire connector the thing won't start. when i unplug the 4 wire con. while van is running it dies. as of now i am stumped i have never seen manifolds get that hot before without any exhaust restriction. any suggestions??

[broughy84]

sounds like timing to me.

[Riche]

try a compression check. See if you have a bent valve.

[Fireplug]

Its running lean way to lean check the carb it might need rebuilt

[Riche]

Fireplug is correct. My answer would be the worst case. Start at the fuel filter on the carb. (inside the fuel line inlet fitting)

[rrousou]

Seen this more often than I can remember.
I hate to say it but your going to have to replace the camshaft. The rear lobes are wore down ( weak spot on GM engines of that size) You can verify by pulling off the valve covers and cranking the engine and watching the valve train lift.