305/350 computer

[C1500KID]

I have a 1998 chevy c1500 that came stock with a 305 v8 4L60e transmission. I want to swap to a (new to me)350 v8 but the engine might or might not come with a 350 computer for the 350 if it does can i just take out my old 305 computer and plug it in ? If not why so and what can i do to get it to run perfectly fine. I live in California and its hard ti find tuners/flashers. Thank you so much for your guys help.

 

[Schurkey]

Is the donor vehicle also a '98 C1500 with a 4L60E and California emissions?

Contact the CARB referee nearest you for advice on engine swaps that will pass emissions testing.

Wild Guess: The computer is the same. The programming is different. ESPECIALLY true if the 350 didn't come in front of a 4L60E transmission of the same year.

 

[C1500KID]

The donor vehicle is a 1997 gmc i don’t know what trans it has i just want to know if a 350 computer will plug and play with my 305

 

[Schurkey]

Not if it's programmed for the wrong transmission, and has the wrong wire harness connectors.

'97 used a different computer than '98. The '97 computer is not well-loved here, although there are some devices sold that can reprogram it. The '98 is more easily re-programmed.

I'm thinking you'll need the '97 engine, the '97 computer, the '97 wire harness...and CARB may still be unwilling to certify it because you've gone backwards with the emissions controls.

You need to talk to a CARB smog referee before you spend a bunch of money and STILL can't get the vehicle registered so it remains undrivable.

Or you need to move the hell out of Commiefornia.

 

[C1500KID]

Am i better off looking for a 1999 350,harness, and computer ?

 

[L31MaxExpress]

Best off just to put a 305 back into it. The 350 swapped the correct way will require going to a referee. The catalytic converter setup and 02 sensor setups are different between a 305 and 350. A 350 might run well enough to get through smog on a 305 PCM but it will not run as well as it could because it will be strangled with the 305s single cat and Y-pipe as well as the 305 tuning. Other option would be sell the 305 truck and buy one that has a 350. Altering the PCM tuning in California is an instant emissions fail.

The engine itself will bolt right in. If I were to swap the 350 in place of the 305, I would do it with the dirt and greases as largely undisturbed as possible. Make them look at it and think it is the same engine that was born in the truck. Correct any obvious leaks but leave it as undisturbed as possible so that it will not have people start asking questions and digging deeper for casting numbers and the like. If you put a nice clean chevy orange painted 350 block in there it will instantly draw attention to it, where a somewhat dirty 350 will be largely ignored. You could always pressure wash the engine bay with some degreaser before and after the swap, just to make it have a consistent look.

 

[C1500KID]

Ok thank you all i appreciate it ill consider this thread closed. I don’t know if there’s a way to close it out. But thank you guys.