i was wondering if 3.4 heads and intake will bolt on to a 2.8 block and if so, what modifications ( if any) do i need to do for it to work. i can get a pair of good heads for cheap.

 

3.4 RWD iron heads will bolt right up. They are basically same heads as the 2.8 and 3.1 except a little more meat in the castings and 1.72" intake/1.42"ex. valves (2.8/3.1 have 1.6"in/1.3"ex)

Any aluminum heads will NOT work.

 

Hey Agood2.8, are you sure that the things will work just bolting them on? I have heard that valve angles are splayed more and that along with the larger valves will not clear the bore on a 2.8 or 3.1 liter engine. Just askin'.

 

if I recall, the 2.8 is the stock block, the 3.1 is a 2.8 stroked, and the 3.4 is a 3.1 bored. As far as I know, the stroke on the 3.1 and 3.4 is the same, so it wouldn't be a problem. I don't know however if the pistons have the cut-outs for the valves though. If I remember right from when I replaced my head gaskets, the piston tops are flat in my 2.8, but I don't know about the other engines. This might be the difference.

 

if you're running a stock cam, everything should clear. turn the motor over by hand before hitting the starter though, always a good idea after changing internals. i disassembeled a 2.8 to use the block for my new 3.1 and it had dish pistons in it...now domes with a high lift cam and i believe the larger valves listed above and have no clearance issues.

 

Invest $6.95 in the GM Performance Parts book available at ANY GM DEALER.
Check out the 60* V-6 section to see every answer for all your questions.
Specs and pictures of aluminum & iron head the only RWD available head.
The $6.95 book & the drive are worth it!
PS ya can buy a used running complete 3.4 mill from a 1993 to 1995 4th Gen F body for as low as $210 & as high as $900.
I pay the high end prices.
IF ya buy the wrecking yards used 3.4 engine, they will toss in the heads for free!

 

The 3.4 has a larger bore. Thats why you can't use a 2.8/3.1 L block, walls are to thin.

I think the valves would be ok but gasket surface ring would need some looking at.