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1990 Trooper 2.8 to 3.4 Engine Swap

PostPosted: Sat Oct 24, 2020 6:54 pm
by Lazytrain
i Know that this thread has been created countless times but I am a trooper geek and i need to do this swap. I have read many of the post through these threads and i still cant find the sought after packet from Ed on this topic. I want to do it right the first time and i have some time and money to get it done. Can i still get the correct 3.4 crate engine from somewhere? Or should i just pull a used engine if i plan on boring out the intake for a 4.3 TBI. I hope yall are willing to help this newbie. I drive a 90 ls 2.8 as my work truck daily and i have an 5x8 enclosed trailer with all my tools. I LOVE my rig but i NEED my power and at 250,000 miles this baby wants it!

Re: 1990 Trooper 2.8 to 3.4 Engine Swap

PostPosted: Sun Oct 25, 2020 6:36 am
by Ed Mc.
Hi, I don't have those files posted online, they're on my PC. So if you'll send me your email-address via a Private Message at this site, I'll forward that info to you.

There is a quite long swap thread here at the Planet, what I call "The World's Longest 3.4 Swap Thread" and it lives up to its name. ... 57&start=0 So check that out, it's got a lot of good info for swappers.

You'll be using the intake & exhaust manifolds off your 2.8, since all that stuff from the 3.4 isn't compatible. Also the accessories, starter, etc.

So when you pull out the 2.8, you can send the intake manifold to a machinist to bore-out the twin TBI intake holes to 1-11/16" which is the bore size of a GM TBI for a 4.3 V6.

There are a few mods to the 3.4 block outlined in the swap info, nothing drastic, the most expensive part is to drill and tap starter mounting holes on the driver's side of the 3.4 block. The GM 2.8 used in the Troopers had the FWD-style starter mounting whereas the RWD S10's and iron-head 3.4's had the starter over on the pssgr's side. There's a drilling jig available from Rodney Dickman Fieros for under $90 shipped, which makes the task very easy.

You can check Jegs, and Summit Racing, among others, for an ATK remanufactured "DCC9" long block. Or have your local machine shop build you one if you can find a 3.4 out of a '93-'95 Camaro/Firebird (VIN "S" as I recall). ... key&ia=web

You could even have your 2.8's heads refreshed and use them on a 3.4 short block, since the 2.8/3.1/3.4 iron heads used on the RWD vehicles all bolt up the same.

Looks like Autozone, O'Reilly's, and numerous others including eBay sell the long block too: ... key&ia=web

I've had my 3.4 Trooper for 18 years and am quite happy with it still. It's way snappier than a 2.8, that's for sure!

HTH & Welcome to the Planet!.......ed

Re: 1990 Trooper 2.8 to 3.4 Engine Swap

PostPosted: Tue Oct 27, 2020 7:47 pm
by geoffinbc
If you are after power you will also want to put in a cam kit and rockers from COMP. It is pretty cheap for the power you get back. If I were to build my engine today I would also use the thinnest Cometic head gasket and get total seal rings to lower the ring drag and improve seal. The thinner gaskets will also improve quench. Custom pistons with a modern metric ring pack would be too much money. I am also seriously considering the Holley Sniper EFI. The self learning TBI would definitely improve performance over the old TBI system.

Re: 1990 Trooper 2.8 to 3.4 Engine Swap

PostPosted: Thu Oct 29, 2020 9:56 pm
by Lazytrain
Thanks for the quick responses, I'll be back soon with updates and more questions i'm sure. Got to get some parts first!