well, all i've done so far was swap the plugs for new ones, gapped to .045 due to having a pertronix and i'm still running lean. the plugs are white, brand new. so i stepped up jets - still lean, right now i'm running 64's in the front and i'm still lean. i haven't done anything else to the engine as it just got back from having the trans rebuilt. what's going on here?

 

any leaks maybe? if your engine is pulling air somewhere then you get lean mixture.
spray sonme WD40 around all hoses connected to intake and carb, as well as intake manifold and carb itself.
don't spray into airclener or carb directly
When idle rpm changes while doing that you found the leak.
how do you know if it's running lean with new spark plugs ? they need ages til they get color (no idfea how long, but mine still lokk like new as well).

 

Is it missing at idle?
Does it have a flat spot when accelerating?
Just no power?
Does it run hotter than usuall?

Did you:
replace the fuel filter
check the filter screen in the tank, old tanks can be full of rust and crud
inspect the fuel line all the way to the tank, looking for a pinch or dent
check the float level in the carb
put a vacuum gauge on it, is it low
check the accelerator pump, is it squirting

Pertronix and plug gap have nothing to do with a lean condition.
As a side note, if you just put in the points eliminator, that will not be a reason to open up the plug gap. You would have to change the coil or add a CDI box to open up the plug gap.

 

no leaks, we checked with a vac gauge and everything and drove around etc. everything else is within spec and brand new - slapped the old stock fuel pump on because the new one kept dropping out - nothing else i know of. coil is a pertronix flamethrower which is why i have the gaps opened up.

 

Was it lean before? And what carb/engine setup?

 

i've still no idea how we actually know it's lean

 

pig rich before with wayyyyy advanced timing. the plugs were black as night. now they're clean as a whistle. we've set the timing down to 34 total and it's still lean.

everyone should know my setup by now

289 .30 over
gt40p heads
xe268h
performer rpm
holley 600 cfm
tri y's etc etc

 

Are they clean, or are they white like used up coal? Post pics of the plugs.

 

clean as a whistle. tiny blips of brown on some of em, the previous ones were dark as hell. ill get pics up tomorrow morning since it's dark out now and about to rain. :|

 

Cleanand/or tan depositsis fine. That's the sign of a good burn. White is lean. Keep running it as is and check the plugs again after a few days.