Heads

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Aluminum Cylinder Head

Taken from the GM Performance catalog, this is comparing it with the gen 2 aluminum heads.
The Gen III cylinder heads are used in late model V6/60 engines for improved performance. They feature an increase of .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.

For now I am just putting the tables up. Very shortly I will have more information as to the changes. Very quickly 96-99 3400 heads have a larger intake valve (1.76 vs 1.72) compared to the gen 2 AL heads and the gen 3 3100 heads. 2000+ 3100 and 3400 heads are the same. (1.76" Intake Valve).








Bolts/Studs
All part numbers listed below are ARP part numbers. Only the kit numbers are part numbers from ARP, the rest of the info is from personal experience with the following parts.

Here's is the stud info for the Gen II and Gen III aluminum heads.

8 - Undercut Long studs (11mm x 1.5 & 7/16" - 20) - ATP5.4LU
8 - Undercut Short studs (11mm x 1.5 & 7/16" - 20) - ATP4.650LU
16 - Hex Nuts (7/16" - 20) - APN58 or 12 point nuts (7/16" - 20) - APN12-1
16 - Washers (7/16" ID 13/16 OD) - APW1316N

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