Which are better, the cast iron ones or the Alloy ones, my other question is how to the cast iron ones fit with out having a lip over the chamber because of the bore being .12" over the old 3.5" bore????

 

Well the Alloy one are supposedly supperior but I was running the Alloy ones after the Castrol and i wuzn't happy with the performance increase.

 

Regardless of the bore size all castiron V6/60 degree heads have a chamber size of 50cc give or take 1-2. The chamber size for the aluminum is 28cc. The variable will be the compression ratio. The aluminum heads will have a higher CR than the cast but will have more of a tendancy to detonate if lower octane fuel is used. If you plan on using a supercharger ot turbo, the cast iron heads are better suited.

 

But what about the diameter, one is 3.5" and the 3.4L bore is 3.620" so won't the old cast iron head's edge hang over the cylinder or the newer heads hang over and not seal the gasket right.

 

well as I said in another post you can get GM Performance heads for the 60 Deg block that flow MUCH better 30 percent intake 40 percent exhaust. The down side? you have to buy the GM Performance parts intake lower&upper too...

 

You seem to be creating a problem out of something that is proven to be already in operation. The 3.4L Camaro uses these heads. The chamber sizes have not changed from those used in the 2.8/3.1 engines. The only thing that changes is the 'quench' area due to the enlargement of the bore. Don't lose any sleep in using these heads for the 3.4 'cause they will work fine.

Camaro_hunder, I took a double take when you wrote that 'upper/lower' intakes for those heads are available from GM. Could you post some part numbers? Are you refering to those used for the 3100? If so they may not fit since those engines were distributorless.

The GMPP site states this about the heads:

These Gen III cylinder heads are used on late model V6/60º engines for improved performance. They feature an increase of 0.040" in intake valve diameter and a reshaped port for a flow improvement of 16.7% at 0.450" of valve lift. The exhaust port has been reshaped into a "D" port configuration for a flow improvement of 31.7% at 0.450" of valve lift.

IMO, I think one is better off just taking the GEN II heads and taking the valves out to 1.82/1.52 like I'm presently doing alomg with porting and polishing. Buy the whole 3.4L from the salvage yards and have at it!

[This message has been edited by x55Cam (edited September 06, 2001).]

 

X55Cam has the correct solution.
It's is WISEST TO BUY A COMPLETE RUNNING 3.4 BLOCK AND GO TO WORK JUST SWAPPING THE STUFF TO SLIP IT UNDER YOUR HOOD.
Honest, you will not be disappointed. IT WORKS GREAT.
Kinda like a freight train rolling & accelerating UP HILL!
So much more power it's a blast!!

I honestly cannot figure out, why some are trying to make such a simple solution so complicated?
And it's not a put down, just an observation.
Learn real quick, more play (add this to the engine), more down time, & more experimenting after you're done.
Keep it simple, & enjoy the results, quicker. I'm still not tired of my new power train. I've gotten used to it, but, oh well. It still hauls major A$$ on the road. Like 80 MPH & close to 30 MPG. I like those results. AND it's dependable & reliable. That's was a major issue with my daily ride.
Keep your plan simple and detail the swap correctly and you win!!

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Chat Soon,
KED85
Karl
1985 Firebird 2.8 to 3.4 swap project for Smog Happy LA, CA

[This message has been edited by KED85 (edited September 07, 2001).]