Do the pushrod 3.4 and the 3.4 TDC use the same pistons, rods, and crank?
How many parts interchange between the two engines?
What are the comparative costs for rebuilding/overhauling these engines?

Do the 3.4 engines have the same main and rod journal diameters as the 2.8?

[This message has been edited by Will (edited 07-21-2000).]

All I know is that the 3.4 DOHC uses the Northstar pistons. Seeing how that is an expensive part I don't think they included that in their mainstream workhorse type engines like the 3400.
I don't know about the connecting rods.

Later

Same crank, different pistons.

check:
www.kb-silvolite.com

Sillhouette:

I thought I heard somewhere that the pistons weren't the same, but the bore was the same, so that a 3.4 TDC could have its compression ratio bumped up by putting Northstar pistons into it.

Terryk:

What about the rods? I heard that SBC rods could be used in the 2.8 if they were shaved down in width a little bit. Is the same true of 3.4's?

I heard that 3.4's have a better designed oiling system than 2.8's. How much better is it? How much more long lived are 3.4's than 2.8's?

[QUOTE]Originally posted by Sillhouette.com:
[B]All I know is that the 3.4 DOHC uses the Northstar pistons.

The 3400 DOHC pistons are not the same as Northstar pistons. The Northstar has a compression ration of 10.25:1 whereas the 3400 DOHC has a compression ratio of 9.25:1 or 9.5:1 depending on whether it came with an auto or manual transmission. I have heard that the bore is the same, so you may be able to put Northstar pistons into a 3400 DOHC, but I'm not sure if the valves would still clear since the 3400 is not a "no-interference" engine. The 3400 DOHC definitely has a better oiling system than the 2.8 - higher pressure, better scavenging etc.

When I had this DOHC apart, it definitely had larger passages. I heard that the routing is different too.

The 3400 SFI and 3400 DOHC/TDC use different block castings due to the addition of the upper end passage where the valve train would be in the SFI engine. However, there is tons the same.

The SBC rods will work if they are narrowed. I used them in an X-11 engine. Frankly, not worth the effort. The stock rods will handle 7000 RPM per the Chevy Power book.

There is some information at:
www.foothill.net/~terryk/X11Z19.HTM

[This message has been edited by terryk (edited 07-22-2000).]

Hey guys speaking of a 3.4 tdc does any one have a web page on how to do the conversion and what parts have to be swapped on the engines.I just picked up a tdc with less than 2k miles and really want this thing in my fiero.Thanks