Senior Tech Team
Join Date: May 2017
Location: Bossier City, Louisiana
Re: Let's Talk LS Swap....Again. 70 Elc SS
I'm about two and a half years into my 70 El Camino swap and have been street legal since last spring. The donor vehicle was a 1999 GMC Sierra with a 5.3 liter LS and a 4L60E transmission. For me, the original engine was a 2-barrel 350 and a TH350 transmission. Unfortunately, the vehicle got parked in the early 80's with plain water in the block that froze through many winters and cracked the block in five places along the oil gallery walls. It was obviously no longer going to be a numbers matching vehicle if that even really mattered to me all that much.
First, a few LS swap truisms:
1 - It will cost you more than rebuilding what you have.
2 - It'll likely take you longer. It's a more complicated build.
But I have no regrets. It is a dependable setup though as always, I work through glitches and bugs occasionally.
Truck, iron block 5.3 donor LS motors are the least expensive. I paid $800 for mine including its powertrain control module with 150,000 miles, good compression at 165-170 PSI and good oil pressure at 50 PSI cold running. I got the transmission for $500. The 6.0 and 6.2 and aluminum block LS motors are substantially higher than that and more complicated. Active Fuel Management, Displacement On Demand and an electronic accelerator pedal will need some additional work on your part.
Driveline angles, shortened drive shaft, possible/probable floor pan surgery for a 4L80E or larger transmission, different motor mounts, maybe different trans cross member, electric fans, maybe different radiator, headers, smaller PS pump pulley, Holley or other oil pan required because some LS oil pans are too low or cause steering interference . . . all of these will absolutely demand your attention. Using all Holley swap parts makes this easier because they are well engineered for each other.
Your PCM will need work to adapt its operating system to its new home and that will cost you maybe $150 or more. If you have a tall truck intake and a cowl induction hood, the hood will close but not if you mount a plastic engine cover on top of your motor.
I read two LS Swap books cover to cover before heading down this road and I don't wish to discourage you. I'm merely preparing you for what can't be avoided.
1970 El Camino under Reconstruction - 5.3L LS VORTEC Engine and 4L60E Transmission