Looking for thoughts & info. I have a 89 blazer full size with a 350 with factory tbi. Engine still runs but it has seen its better days. I am looking to either rebuild my engine or replace it. What I want to know is if I stay with the tbi, how much cam can I use with factory set up? Or would I be better off going with a carbureted motor? If I go with the carb set up can I still use the in tank fuel pump or change & use manual pump? I will be using it on the street & taking it to the beach & driving on sand. I do not want anything too wild, just with a little more grunt. Thanks

 

TBI is a waste of metal if you want any power. For a carb you can use the in-tank fuel pump, but you will need to use a fuel pressure regulator with a return line. Fuel pump needs to flow fuel to keep it cool.

Hot ticket for you would be the 1996-2000 Goodwrench 350 truck motor. GM Goodwrench 1996-2000 Truck 350ci/255HP 5.7L Crate Engine | JEGS Brand new engine (not rebuilt) and a definite power upgrade with the good heads. Put an intake, a carb, a mild cam and a distributor in it and you will be well over 325 HP and wonder how you ever drove that TBI motor. Figure a few thousand $$$ for the swap and performance parts (it's an easy one). Be careful about any emissions testing though.

 

Why not an auto tuning EFI kit? I've seen a few and it looks to be about $1400 for a compatible kit all in?

I'll admit I may be missing something (budget restriction?). Just wanted to ask.

 

Just doing my 4.3 V6 with the same issue.

It depends on the reasons for the swap or changes applied and what the outcome should be.
For a fun truck I guess that retaining some of the OEM indications is not so important.
Changing the cam and it being outside computer specs the TBI would need a re-calibration for the different VE (volumetric efficiency) of the engine.
That can become a hassle. For my build I have not been able to find a good calibration that can be swapped for 50 - 80$. So, as I have to retain the TBI for the catalytic converter to work properly it will be onto the dyno and do a day or two of pulls to come up with the correct VE tables.

A carb will definitively be the easy swap. The lack of the TBI should not interfere too much with the remaining car electronics. (Still depending on what you want to retain.) The ECU may generate some outputs which are needed by the dash or the ignition. It might be necessary to provide the ECU with some resistances of the proper value for the injectors. But that is simply me being a perfectionist.

Would love to put one of the fully programmable EFI (TBI style) kits on mine. Unfortunately I suspect them all to bee way too big for the 4.3 build which aims at good filling at low rpm for good torque and only some 200 hp.