1985 GMC S-15 engine swap question (2.8 to 3.4)

[supernova72]

Hello, first time to your forum. I've seen bits and pieces of great info regarding engine swap option on 1st gen trucks. I just started researching the 2.8 to 3.4 engine swap for my 1985 GMC S-15. Finally realizing the GM HT crate motor is discontinued My motor runs well but is just a bit tired and looking for a bit more power (160HP ish). This truck is a 4 X 4 auto trans extended cab.

From what I've read is my "Plan B" would be to find a 93-95 Camaro 3.4L. Or even buy a remanufactured one? Initial search from engine remans is "nothing available" although that was just one rebuilder.

Can you point me to a thread that describes my options? Truck use is weekend run to Home Depot and one day a week to work. My dad ordered it new back in 1985 and I'm trying to keep it in the family and running well. Cheers.

[34blazer]

I have my 3.4 for sale, now located at 88330. If you don't want to tune, you can swap the cam out for something less aggressive.

http://60degreev6.com/forum/showthread.php/51455-3-4-ironhead-feeler

[supernova72]

I have my 3.4 for sale, now located at 88330. If you don't want to tune, you can swap the cam out for something less aggressive.

http://60degreev6.com/forum/showthre...ronhead-feeler

Thanks. I'm more looking for a bit more power and am thinking your engine might be more than I need. My performance car is a 1972 SB Nova. Ha!

I live in Seattle WA.

[Ed_Mc.]

Hey, that's a nice-looking old S-10 pu! You might give Geoff a holler, he's up in Surrey, BC (just across the Wa border) and had a good used 3.4 for sale, really cheap.

You're absolutely correct in that GM has discontinued the HT 3.4, so your best bet otherwise would be to scour Craigslist or check local wrecking yards & pull/yank-a-part places. www.car-part.com will pull up local or national wrecking yard databases for your search.

Geoff goes by user name Geoffinbc so give him a holler, I'm not sure if he's sold it yet but if he still has it, I doubt you'd find a better deal on a running engine.

I have a Camaro 3.4 in my '90 Trooper, it's a heck of an upgrade from a TBI'd 2.8. Even with a 2-bbl carb, GM rated this motor in an S-series at 160hp. I expect mine is getting even more than that with big-bore TBI, a bored-to-match intake, and roller-tipped 1.6:1 rocker arms. Still need to work on the exhaust, the OEM is quite wimpy for a 3.4!

If you do swap to a 3.4, you'll need a newer flywheel or flexplate, since the later-style engines are internally balanced. The older 2.8's externally-balanced flywheel, bolted to a 3.4, will shake things up quite a bit!

Everything else should bolt up; I think you can use the '85 oil pan, but if it doesn't fit, a pan from an 88-up 2.8 will work (I'm assuming your truck is a 4wd, if it's a 2wd you can just use the Camaro pan). If you're using a 4WD pan, it requires a deeper oil screen/pickup assembly (Melling 245-S).

Anyway, we're almost neighbors, I'm over on the Kitsap Peninsula near Poulsbo.

Hope that helps and G'luck with the swap........ed

[geoffinbc]

Yea it is still for sale. Actually the last 3.4L I had from my S-10 was sold to a Trooper owner from Bellingham. I can sell you just the long block for $360 Canadian if you come pick it up. Right now with the way the dollar is you will get a 20% discount. PM me if your interested in the engine.

[Guest]

There are several people that have tried to use the Camaro oil pan in a 2WD S-series without luck. They have had to swap the S-series oil pan onto the engine to fit properly. IIRC the front of the pan is a little deeper or the notch for the cross member is not long enough.

[supernova72]

Hey, that's a nice-looking old S-10 pu! You might give Geoff a holler, he's up in Surrey, BC (just across the Wa border) and had a good used 3.4 for sale, really cheap.

You're absolutely correct in that GM has discontinued the HT 3.4, so your best bet otherwise would be to scour Craigslist or check local wrecking yards & pull/yank-a-part places. www.car-part.com will pull up local or national wrecking yard databases for your search.

Geoff goes by user name Geoffinbc so give him a holler, I'm not sure if he's sold it yet but if he still has it, I doubt you'd find a better deal on a running engine.

I have a Camaro 3.4 in my '90 Trooper, it's a heck of an upgrade from a TBI'd 2.8. Even with a 2-bbl carb, GM rated this motor in an S-series at 160hp. I expect mine is getting even more than that with big-bore TBI, a bored-to-match intake, and roller-tipped 1.6:1 rocker arms. Still need to work on the exhaust, the OEM is quite wimpy for a 3.4!

If you do swap to a 3.4, you'll need a newer flywheel or flexplate, since the later-style engines are internally balanced. The older 2.8's externally-balanced flywheel, bolted to a 3.4, will shake things up quite a bit!

Everything else should bolt up; I think you can use the '85 oil pan, but if it doesn't fit, a pan from an 88-up 2.8 will work (I'm assuming your truck is a 4wd, if it's a 2wd you can just use the Camaro pan). If you're using a 4WD pan, it requires a deeper oil screen/pickup assembly (Melling 245-S).

Anyway, we're almost neighbors, I'm over on the Kitsap Peninsula near Poulsbo.

Hope that helps and G'luck with the swap........ed

Thanks for the detailed note. I'll need to assess my next steps on this. This is a 4X4 yes and have read that the oil pan/pump would need to be swapped. I did not know about the flex plate however? This is an auto trans truck. Again, thanks for the info.

[supernova72]

Yea it is still for sale. Actually the last 3.4L I had from my S-10 was sold to a Trooper owner from Bellingham. I can sell you just the long block for $360 Canadian if you come pick it up. Right now with the way the dollar is you will get a 20% discount. PM me if your interested in the engine.

Thanks. I'm mulling over what my next steps are. Sort of a backyard hack mechanic so for me to rebuild a motor would be a tall task