Well i put in some #65 injectors, with the regulator backed all the way off. Drove it around, pulls pretty good. BUT when I got back I pulled a few plugs and they are fouled, I had also noticed a missfire.

My dad thinks that the Holley 670 is the problem and that i should put the original TBI on it with the upgraded injectors. Do you guys think this would fix my problem. My MAP and O2 are working.

cliffs notes version of my mods: Lt4 cam + vortec heads + basic engine rebuild

 

If you're running a 305 with those mods, then the holley is the problem. What intake do you have? I pretty much got ripped to shreds in my post "Went to the track..." for using the stock intake manifold with the holley, as I probably deserved the critism for mis-matching my parts. I knew the injectors were making me run rich(your problam as well), however I thought the gasket supplied with the holley would help take care of the 2" holley bore to the stock intake 1 11/16" problem. But I guess it actually causes a turbulance and hurts performance. Not to be a smart ***, but it has always ran better with the holley. However, I do trust the guys giving me advise, and will try to follow it as $$$ allow.
Anyways, to get to the point, if you are running a 350 then the 670 would work great. However, if you have a 305, then 65pph injectors are way too large, even with your heads and cam. Putting those injectors in the stock TBI, won't work to begin with because they won't fit, but even if they did, you would still run to rich. The only way I know around it is to either chip to get smaller injectors. Sorry about the long post, but hopefully it helps. Good luck Roy

 

I have a 4bbl intake with an adaptor. i tried the stock holley #83 (way too rich) and stock 305 (too lean), so im assuming i can make these work.

 

Im gonna try to run gm 55 pph or 65 injectors on mine when I get a 670. Mods are close, lt1 cam, vortec heads, performer intake. My 45 pph are running really rich down low and still lean out a little up top at wot. My fuel pressure is pretty damn high, but Im not quite sure what it is since Im too poor to afford a gague lol.

Aucutally im gonna couple the new injectors with the gm vacuum afpr. There is a pretty good thread about it from about a year ago that just popped back up. That should solve the rich/lean problem Im having.

 

desktop dyno says im supposed to make around 315 HP ... *shrug*