305 to 350 Swap: Passed CA Smog!

[RAMZ 94]

Newer to this forum, but wanted to share my recent experience with a engine swap.

I have a ‘94 Chevy Single Cab Stepside that originally came with a 305 TBI and 4L60e transmission. The truck had been sitting for about 7-8 years and the time (and money) finally came to get her back on the road. The engine went out back when and I wanted to replace the old one with a rebuilt/remanufactured engine.

I live in California, so you all probably already know how much smog laws suck around here.

Long story-short, after a lot of research on the CA Bureu of Automotive Repair website (https://www.bar.ca.gov/pdf/Smog_Check_Reference_Guide.pdf) and this this forum, I found literature that said that the GM 305 and GM 350 were both in the same “engine family” and followed the same smog restrictions.

After taking my findings to my mechanic, we agreed that to make this swap work and pass smog, we had to also swap the following to match Greg 350 engine specs:

-Engine ECU ($100 on ebay)
-TBI Injectors x2 (AC Adelco $200)
-Knock Sensors ($30)

I’m happy to tell you my truck passed smog with flying colors last week and she is finally back in the road; all under stupid LEGAL California laws.

I still have a laundry list of things to repair/replace before she is back to her former glory, but at least now she’s a running project!

 

[Ebustos]

Did you keep to 1 catalytic converter or change it to the dual?

 

[PlayingWithTBI]

Did you keep to 1 catalytic converter or change it to the dual?

You have to have the same number of Cats in the same location as the original. Otherwise, under inspection (if the examiner knows what they're looking at) it'll fail.

Edit: OP hasn't been seen since Feb, 2022. You can click on their Avatar to see when they've last been seen.

 

[L31MaxExpress]

Did you keep to 1 catalytic converter or change it to the dual?

TBIs only have 1 cat regardless if it is a 305 or 350.