ive been readin alot of this board and read alot about guys swapping a 350 from a 305 tbi and read alot about tuning the car and computer and what not. my car runs great with the 350 block freshly rebuilt, but how much power is being held back do you think with no tuning what so ever? and how should i tune it? i know i need bigger injectors, im looking into the 2" or a 454 setup. let me know on what you think the best route of tuning is thanks.

 

I think your best bet is to find a used ECM and chip from an 87 - 95 Chevy Truck. Should just be able to swap out the ECM and be running with the stock 350 tune. You could probably use one from any L05 setup. Caprice, Impala, Van, Truck, etc...

Then, you could get into tuning it after that point.

 

Just to make sure we're on the same page, when people say tuning around here, they mean chip tuning. Check out the stickies on DIY prom board for more info.

 

Simply put, ALOT. If you are still running the 305 injectors and 305 ECM, you are VERY LEAN. LEAN enough to BURN pistons.

 

how would it be after i put a 2" TB on it or a 454 tb???

 

The tb is only a flow restriction therefore will only hinder air flow (less power) wouldn't be anything to cause damage to your motor. The big injecters and fuel pump are what you need, along with a adjustable fpr for sure. If you can tune the fuel pressure real good and get a holley 670 2in tb or 454 2in tb with 454 or 350 injecters and a good fuel pump with properly tuned fuel pressure you will be a lot better off than you are now but, definetly could still be running lean on you.

 

I have the same setup. I am rich at idle, cam lowering vacuum at idle. Surprised I don't have a MAP code. At cruise it is a little lean. Long term FT averages 130 to 132. Check you fuel trim or o2 numbers to see if you are running lean.

Would a truck 350 tb help? I can't find a 454 tb.

 

130-132 isn't all that bad. I only shoot for + or - 2 blm from 128 when I tune. You have to keep in mind your ecm is compensating any time your blm's aren't pegged at their high or low limits. Which is 145 and 108 in most cals. Any time your between these limits your ecm is able to keep your actual afr at 14.7. This is why your able to get away with some mods before drivability problems arise. The problem with this is that once you go WOT your ECM ignores your O2 sensor and only looks at your VE table, which isn't correct for your engine now. A simple data log will show you if you have pushed your ECM too far to be able to compensate. With that said, I find engines run slightly better when the ECM is making little to no changes (i.e. 128 blm) I see the afr is more stable. This is that last 5% of the tune that gives your motor that spunk that a well tuned motor has.