85 top end on an odd-fire?

[corkatoa]

I had posted in the hot-air section, but I think this is a question for this forum.

Has anybody done this? I couldn't find a thread for it.
I have recently acquired 2 older engines and one of them is an odd-fire (no crank offset). Seems to be a stronger crank. Since it has the same firing order, I was thinking of putting my 1985 gn top end (heads, intake,etc) on it instead of the 79 block. Block seems the same, a few minor differences but should work. I think the main problem would be that newer head gaskets are thicker, therefore I will have a pushrod issue. Easily overcome I would think.

If nobody has done it, I guess it should get done for the sake of knowledge? I would be sure it has been done but???

 

[Mike E]

If you keep the odd fire crank in it, you would have timing problems. The GN crank trigger and ignition expect to fire every 120 degrees, but and odd fire is something like 105, 135, 105, 135. so you would be 15 degrees low on timing in one cylinder then 15 too high on the next. The block should work otherwise, but I thought those older blocks were really small bore.

 

[corkatoa]

That is what i am struggling to understand. I have seen the timing chart now and see the difference.

The block has .020 pistons (stamped on top) in it and the bore measures 3.82. I assume that was to bring it up to 3.8l? but...

I had read on gnttype that all these engines were 3.8 bore from the beginning.

I will be happy if I can use the block. Really just messing around to see what is possible.

thanks for the input.

 

[ek02]

According to Pat Ganahl's V6 Perofrmance book, there were many variations of heads and blocks. All heads will physically bolt to the early odd fire blocks, but the water passage locations were changed a few times. If you have an 85 head gasket, put it on the odd fire block to see if any water passages don't line up. I scanned the page from the book that deals with this issue. If it does not attach to this post I can e-mail it to you.