Just rebuilt my 327 "mildly" and noticed it had a spread bore manifold and a square bore carb. Can this be a problem? I have the adaptor plate--should I use it? The damn motor has no guts and pings!

 

Without an adaptor plate, you can't bolt a square bore carb onto a spreadbore manifold. One of them needs a dual bolt pattern and even then there may be a problem if the proper gasket isn't used.

As for how it runs, you'll need to do some basic troubleshooting. Pinging is a timing or octane issue.

 

or a lean condition causing the cylinder temps to skyrocket and leading to pinging

 

spreadbore wouldnt allow 2 of the squarebore barrels to even openeven if you got it to bolt up somehow, check summit they have adapters for like $20 er somethin, otherwise ebay, or get a recently ran quadrajet off of somethin at the junkyard

squarebore and spreadbore just simply dont mix well though, you're probably best off getting a spreadbore carb if you keep the manifold, cuz i ran an adapter, had hood clearance issues (now i have a hood scoop) and it caused some funky turbulence in the manifold, but yea that's why it runs like crap, I'm amazed that it even runs at all