340 has no balls

fourspeed said
Put a little bigger cam in it and bleed off some cylinder pressure. That should get it to run reasonably well on pump gas and still have enough spark advance. That's assuming the rest of the engine is in good shape...

Mine ran like crap on 93 octane pump gas with all stock innards. Retarding the timing helped somewhat, but it was never right.

If you bail on the 340, I'm sure you'll have no trouble selling it.

First, is it a fresh motor?

What cam are you running?

Was it degreed in?

Pistons, forged or cast? Compression?

What is your total timing set at?

Take small steps looking into what the problem is, use a process of elimination, get the manual out and strat troubleshooting. Don't go chasing your problem with more parts. Start fro scratch and set a baseline and go from there.