Bob, when having trouble like this, don't be afraid to try things like a lot of timing or jet changes. Keep away from the drills unless you have replacement parts, just incase! The 235 will take a whole lot of abuse, so extra timing won't hurt it abit. Check the voltage to the distributor like one of the above post mentioned, make sure its a full 12 volts till you get this straightened out. Thats one of the advantages of HEI, a stronger more steady spark at low rpms. I notice a better idle quality when I switched my 250 over.
You are southeast USA, whats the temps. like there? is it cool and damp?
Heated intakes help no matter where you are, just not as much if its hot and dry air.
Try making a crude air duct around the exhaust manifold and pipe the air up to the intake so as to heat it as much as you can.
Try bending the accelerator pump linkage, if its external, so they don't squirt as much fuel.
Try turning the idle jets way rich or lean.
Theres plenty to try, just keep after it.... Joe
