Retune my entire carb after installing new heads?

Bewy said

Your new heads probably have larger intake port volume, which reduces velocity AND carb signal. This explains your symptoms.

Getting leaner when hot does not sound right.....expect it be leaner when cold.

What:
- idle vacuum
- idle timing
- idle rpm
- t/slot position
- carb

Click to expand...

Thanks, that makes sense. I'm sure the intake ports are bigger, although still the standard Mopar big-block size.

Naturally it's lean when cold and needs throttle tickling to keep it alive until it gets warm. But after a 30 minute drive on the highway, the AFR gauge showed leaner again and it wouldn't idle without attention to the throttle.

Only thing I know changes with fully hot engine would be the alum. heads (lash grows an estimated .006", I haven't had time to check it when hot yet). I have a 1/2" phenolic spacer and a 1/2" nitrous plate between the manifold and the carb as well as a six-pak hood scoop - don't think it's fuel boiling.