Part 2 of my ’71 Chevy LS engine swap. In this part, I pick up my new engine and stick it where the sun don’t shine (my garage of course…).
Hmmm, so where did we leave off with Part 1….. Oh ya, I had sold my motor on Craigslist and was left with a truck in the garage that has no motor. Time to fix that.
This motor I picked up with the Honda-Hauler was from a guy I found on Craigslist. He sells LS motors on the side as a hobby/business (profitable hobby?). His process is that he gets the motor from the junkyard AFTER he gets a deposit from you, the idea here is that most junkyards have a warranty/return policy that starts the day the motor is bought so if he waits until he has a buyer to buy the engine the warranty will last longer (genius!).
So I put down a deposit and got a supposedly 70K mile 5.3 LS Motor out of an early 2000’s GMC Yukon with a 6 month warranty provided by the junkyard. The Craigslist guy takes the wiring harness and reworks it to include the necessary fuses/relays then flashes the computer removing the anti-theft VATS (Vehicle Anti Theft System) and doing a slight performance tune. Since I was going to be bolting it up to my TH400, he just programmed the computer as if it had a manual transmission (no electronics in the TH400’s).
I want to clear up some confusion here. I did A LOT of research on bolting the newer LS motor to the older style TH400 transmission, most of which just confused me even more. The truth is, this is possible and quite easy to do. If you get a 4.8/5.3 engine with a dished flexplate the ONLY part you need is a Hughes Performance HP3795 Transmission Adapter. The reason you need this is because the LS motors have a crank that is .4 inches shorter than the older Chevy engines. The dished style of the flex plate makes for the same bolt pattern, but the Hughes flexplate adapter spaces the crank out .4″ to make up for the shorter crank.
Still confused? Here are LOTS of pictures:
Warning, make sure you use Locktite on the 6 flexplate bolts and follow proper torque sequence alternating side to side.
First time through torque bolts to 15 ft/lbs
Second round torque to 37 ft/lbs
Third and final round torque to 74 ft/lbs
The only complaint I can even come up with on my Craigslist engine guy is that just before we hooked the engine up to the cherry picker, I noticed the MAP sensor on the intake manifold was broken off. Not a huge deal because it is a little plastic sensor that can be had for ~$10-20 bucks. The sucky part was that I was trying to get the little sensor stub out of the intake and ended up dropping it into the manifold deeper into the engine. So I got the fun task of taking the intake off to play hide and go seek.
I am now working on some emissions blockoff plates that I will cover in part 3 when I start plumbing and wiring the motor. I am also working on doing a full LED light conversion for all of the lights except the headlights (DOT approved round LED headlights are still too $$$$$$ for my budget).
- Ol’ Blue LS Swap LINK INDEX:
- Part 1: Removal of the 496 BB and wire harness
- Part 2: Initial install of LS motor and adapting to TH400
- Part 3: Custom motor mounts and EGR blockoff plates
- Part 4: Power steering adapter and LS ECM installation
- Part 5: LS manifold V-band and exhaust installation
- Part 6: Coolant/fuel system installation – First Start!
- Part 7: Throttle Cable/Intake/DIY ECM mount
- Part 8: Painless wire harness install and LED conversion
- Part 9: Reconfigure the exhaust…again and finish LED’s