I have a 1988 Trans am with a Throttle body injection unit on a 305
I can get a good deal on a fresh,rebuilt 305. Everythings new. But the engine is from 1985. Would i somehow be able to put my intake and TBI unit on that motor? Or is there a special adapter i have to buy? Thanks for the help guys!

 

It will fit - might have to drill out the center 4 intake holes - perimeter bolt heads had different intake hole angle than center-bolt heads.

Should consider a 350 for close to same money (unless it's an exceptional deal) - everything will bolt up to a 350 as well - just need 350 chip, 350 knock sensor, and 350 injectors for the TBI - and you'll have a ton more power.

 

Would my Tbi unit be Able to be mounted on that intake with an adapter?just trying to avoid machine shop work

 

Yeah - there are adapters available. But - the 1985 motor is a carb motor right? The carb intake is going to have the 4 holes in it for the 4 barrels of the carb. I'm not sure how this translates to the TBI unit, and if it will affect performance.

Usually, TBI folks use these TBI adapters to place a TBI onto a single or dual plane square bore intake - an aftermarket intake with a big square hole in the top. The adapter plate simply connects the 3 bolts from the TBI unit to the 4 bolt holes of the carb intake. But on a square bore intake, you have a big square hole - the bottom holes on the TBI unit just basically dump into the big square hole of the carb intake.

But a factory carb intake has 4 round holes in the top that match the 4 round holes on the factory carb. Not sure if there's an adapter that would 'line up' the round holes on the bottom of the TBI unit to the round holes on the factory carb intake.

Does that make sense? It's not just the issue of getting the 3 bolt holes of the TBI unit to connect to the 4 bolt holes of a carbed intake, it's also a matter of making sure that the air/fuel mixture will easily move from the TBI unit INTO the intake without restriction.

Maybe someone more familiar with the 'barrel' pattern of the TBI unit and the factory Quad carb will chime in with more/better info. Or you could call Summit tech support and ask them.

But elongating the holes on the TBI intake is not that big of a deal. Most folks do it with a dremel or just a drill and bit. The intake in aluminum, so it's easy to work. The intake gasket will seal it off, so there's no real issue with messing it up really. There's several threads on TGO about doing it, maybe even some with pics. It's not anything that you'd need a machine shop for - and even if you did, it wouldn't be much cost (should take someone with great tools like a machine shop 20 minutes to do).

Hope that helps. Not sure I always get into words what my feeble brain is thinking

Oh - another option to make things easy - buy a square bore intake, and then get the adapter for the TBI. Weiand makes some nice intakes, much cheaper than some others - think when I did this I used an Action Plus Weiand intake, square bore, dual plane, maybe like $125 new, and the adapter plate I ordered from local Advance Auto think it was $39.

But it cost way less than that to even pay a machine shop to elongate/match up those 4 intake holes.