There is SO MUCH misinformation out there on doing a CA legal swap! I've now done two. My first was a 3RZ swap in a Toyota. The second was a LQ4 swap into my V2500 Suburban. I thought I'd post some details of the swap while it is still fresh in my mind. This is by no means a replacement for the engine swap guidelines from the Bureau of Automotive Repair, but as you'll see when you look at them, they're clear as mud to the layperson. I hope this article will shed a little light on what is needed to do a CA legal engine swap.
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PART I: MY SWAP STORY
I purchased a 1991 V2500 Suburban. It came with a TBI 350, which back in 1991 had a whopping 185 HP. Transmission was a 4L80E. I was loving the old Squarebody, but the poor old truck couldn't get out of it's own way! The first week of owning it I was already dreaming about engine swaps.
I knew enough details about the CA engine swap requirements to know I needed to pick a donor vehicle that was somewhat similar to my vehicle. Knowing the LQ4 was found in 3/4 ton vehicles, I guessed it was going to be ok in my 3/4 ton Suburban. With what I know now about Emissions Category Certifications, I got lucky. I should have done some deeper digging on the requirements. I'll elaborate later in this article.
I decided the 6.0L LQ4 was what I wanted and when I found a fair price on one at a local wrecking yard, I took the plunge. I knew the owner of the yard, so I was able to take the donor truck home for a month and pull the engine myself. It was really handy having the donor just outside the garage. Anytime I needed a bolt, bracket, clip, etc., I could source one off the donor truck. The donor was a 2002 Chevy 2500HD 2wd. Tranny was a 4L80E, but the yard had already sold the tranny.
Just as I decided to pull the trigger on this engine swap, I got the weekly email that comes from this GM Squarebody forum. In the email was "1991 5.3L 2500 Burb" listed in the engine swap forum by Kelvin. I couldn't believe my eyes! Talk about good timing! You can find the thread here
https://www.gmsquarebody.com/threads/1991-5-3l-2500-burb.31558/
I read through the thread and found that he was nearly finishing his swap. I ended up contacting Kelvin and next thing I knew he was texting me his entire parts list, which he's since added to his engine swap thread. Please check it out, so much good info there. Saved me hours of research and tracking down part numbers.
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Using the same motor mount adapter plates as Kelvin, the engine bolted right in, requiring no changes to my transmission crossmember. Technically it required no frame mods at all... however it was really tight at the passenger side manifold, where it bulges out for the EGR pipe. I ground a little steel off the upper edge of the frame to be sure it wouldn't hit the frame when the motor torques over on it's mounts. The other spot the engine is really tight is behind the driver's side head. It did fit without firewall modifications or massaging.
Not knowing how many miles were on my existing 4L80E, I opted to have a local shop with a great reputation (Bob's Almaden Transmission, San Jose) build me a 4L80E. I'm really glad I did. My 91 tranny was one of the first years of the 4L80E and many improvements were made over the years. I also learned one (maybe more than one) of the shift solenoids must be changed out to work with the newer PCM, so I didn't have to deal with that, since I had him build me the correct 4L80E for my 2002 motor.
And now... lets get to the specific CA stuff. CA requires that the motor be 100% functioning as it was from the factory, all the way down to secondary O2 sensors, EGR, EVAP, etc... this was the main reason I wanted the donor vehicle nearby while completing the swap. I wanted to know every little piece was available to me.
The EVAP system requires that the PCM know the pressure in the fuel tank. My 91 tank had no provision for that pressure sender. I ended up filling the tank with shielding gas and then welding a bung to the tank, to get the thickness required to hold the sender. Then I drilled through the bung and slid my sender into place. I read some guys have just put a T in their gas tank vent line and installed the sender there, since it'll be measuring the same pressure. I just kept envisioning getting a stickler of a referee, so I opted to put mine directly in the tank, as it was designed.
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