How to: 2.8 V6-3.4 V6 Swap
 

The main thing to remember about this swap is you are trying to re-create your 2.8 but on a 3.4 block. Why? to fool inspection personnel, the engine will look like your old one but definitly out-perform it! Also, to avoid computer wiring nightmares, and to simply get more out of your V6 for probably 1/3 of the price of the V8 swap. You have to re-use as much as possible, and this swap should finish around the $800 mark, engine block included

Order the block-
3.4 Litre block w/ intake, exhaust manifolds, oil pan
Buy a new Timing Chain and water pump

change everything over from the 2.8 to the 3.4, front to back, side to side,
Harmonic balancer and all

Swap 3.4 injectors to 2.8 fuel rail
Re-Use old distributor

Things to buy-
Complete 2.8 gasket set
Rear main seal
Distributor gasket
Exhaust manifold donuts

Of course, this list is not complete but it is close i would say. Simply buy the 3.4, and study it, then when you are completely comfortable handling it, pull that 2.8 out and change all the parts that are different on the 3.4. You want your 3.4 to look almost exactly the same as the old 2.8! When its all said and done, you should have spare 3.4 parts to make some of your money back!

Help!!!
 

I know this dosent pertain much to CAMAROS....but i really need help!! I bought a 1985 chevy blazer that originally had a 2.8 in it. The guy told me when I bought it that they done an engine swap and it now has a 3.4 in it from a "95 firebird" so he says. The motor has a serpentine belt on it but its a carburated engine. It has a rochester 2SE Varajet on it and it runs like crap. My mechanic told me that one of the lobes on the camshaft was wore really bad and thats what was causing my trouble. I called the Summit Racing tec line to price a camhaft and he told me there was no way it was a 3.4 because it was carburated, and that it had a 2.8 in it. HOW IN THE LORD DO I KNOW WHAT I HAVE??? The summit guy said the 2.8's have a 2 peice intake...after looking at mine it appears to be a 1 piece. Please HELLLLPPPP!!

The Blazer that you bought may very well have a 3.4 long block in it as described by the first post in this thread. The Summit tech was just reading from a computer screen or book telling him what engines were *originally* installed in the Blazer and a 3.4L was definitely not on the list.
I used to own an 83 GMC S-15 pickup with the 2.8 and that engine had a one-piece intake for sure. Maybe the later 85 was two-piece...
The only way that I can suggest identifying what engine is in your Blazer is to look at the machined pad on the driver's side of the block all the way at the back. For the 3.4 the VIN derivative for the vehicle it was originally installed in is stamped there. Here's the pad info from the 3.4 out of my 94 Camaro.
If there's really a 3.4 in the Blazer you'll need to buy a 3.4 camshaft.