Ok, Im building a low buck 383. Not cheapo, but not racing. The usual, 4 bolt main, nodular iron cranck (new), Forged rods, Keith black pistons, street strip cam. I plan on running no more than 5,500 rpm. powerband between 2,500 to 5,500. My question is, Can I keep the TBI system?? I dont want to mess with converting to carb and changing the distributor. What do I have to do to the TBI system to handle the 383?? Ditching the 305.

prob need either a 454 tbi unit or holley unit and #65 injectors but you should be able to use tbi providing your cam isnt radical.

Id get the larger 80 pph injectors with the 383. Gonna want all teh fuel you can get. It should be ok so long as the powerband doesnt go to an excessivly high rpm.

why not use the early 90 lb injectors? i think i read a while back there was a reliability issue with 90 vs 80 lbs. the 80's being more favorable. i dont see why? maybe someone had a experience with 90's that was not favorable or possibly the GM supplier for 90's are diff than 80's.

People had problems with the chysler injectors that holley was putting in their throttle bodies, they have recently switched. I would stay away from holley because they rate their injectors at a much high than stock fuel pressure. Their BB TB really has 65 pph injectors but if you run them at 25 psi they will act like 90 lb/hr. I would get the true 90 lb/hr injectors and be prepared to turn up the pressure. Quick rule of thumb with TBI(correct me if I'm wrong) TBI has been PROVEN to 350 hp and can THEORETICALY support 400 hp.

All this is dependent on one big factor. Chip tuning. You will HAVE to learn to tune yourself if you ever want to have something that will do more than get you from one side of town to the other. Check out the DIY prom board and read Traxion's prom burning intro.

I am also doing something very similar. I am going from a 283 to 383. I want to keep the TBI injection. I see posting about 50-80 lbs injectors. I may not be the sharpest tack in the box here, isn't the fuel pressure in TBI around 35 PSI? What else are we talking here? Or I should ahve read something that I didn't, which is normal for me!!

JP, Dimented, Bron and Dewey will chime in but I will give you caveman explanation to get you started. They will chime in with their unmatched expertise soon.

The TBI fuel pressure can be varied and you can control that via the chip and regulator. The poundage readings you are refering to are the flow rates for the inejctors. Basically the higher the number the more fuel that comes out of them. However, the really good tuners find the right amount of flow vs pressure to feed their combo. Everyone has a slightly different method in this respect but the end goal is always identical. The stock system only opporates at a mere 12psi (if you are lucky) and can barely feed the stock parts. Adding serious mods (heads, cam and chip tuning) will also require attention to the fuel system as well (ie. fuel pump, regulator, and injectors).

ok!! So what we have here is lots of fun things to do over the winter!! Thanks Shifty!! Is there any stickies on TBI mods that will address all of these issues? Bigger injectors that will require more fuel and fuel regulation? I do know that when I had my 283 in with a monster cam, for that engine, it was running very very rich. It would constantly load up!! Kinda cool to a point, NOT!!!! Heads will be gone through and areas touched up to make them flow a little better. Not talking way out port and polish. Daily driver that will eat most "normal" appearing mustangs!! Just a little goal of mine that is all!!

winter? now would be a good time to study up on datalogging and chip tuning.