Milling AMC Cylinder Heads

[amundaza]

I have a pair of 59 cc 304 heads that have been ported & polished, then machined to accept 1.94" Chevy intake valves and 1.50" Chevy exhaust valves. The rocker bosses have been milled down to accept 3/8" studs for roller rockers.

The combustion chambers have been opened up to about 62 cc.

I'm considering enlarging the exhaust valve to a 1.60" and installing these on the 360 in my Grand Wagoneer.

How much can the AMC heads be milled down to raise compression??

MY GW has an 8.25:1 motor (1989), which has been rebuilt ... I assume 8.25:1, but I'll know more when I get the heads off and can check piston-to-deck clearance.

I don't have a lot more work to do on these heads to bolt them on, but don't really want to drop my compression all that much.

Also, when running guide plates on AMC heads (that need them ... round pushrod holes), at the center 2 holes, the casting is raised up. It looks like that area would need to have the casting milled or ground down, so that guide plates can be installed. Does anyone have pictures of this done, that I can see what/where to mill/grind? Thanks!


Sincerely,
GregTaylor
Oxford, MI

1989 Grand Wagoneer : Water/Hydrogen Injection 360-V8. 4.5" lift 31" BFG A/T's. Killer32 front bumper

[jeepsr4ever]

You never know if you have to take off material there until you do a final fitment. Also .023" will net you a .5 in compression on milling the heads.

[amundaza]

Thanks for the quick reply. From looking at how the bosses are milled down, they are lower than the center holes' casting area, so my guide plates would not bolt down 'flat'.

Also, can I mill the heads .046" to get a full point compression raise? At 62 cc and stock deck clearance (according to TSM ... 0.011 for 1989), I get 8.36:1 compression.

Thanks,
Greg :) <><

[82Waggy]

I had to mill down the section you are describing to install guideplates:

http://i142.photobucket.com/albums/r107/82Waggy/401/head5.jpg

[jeepsr4ever]

Did you drill out the slots in those 6090 heads or were you trying to capture the pushrod at the highest point you could?

[82Waggy]

I drilled out the slots and was trying to capture the pushrod as close to the rocker as possible. I'm not a fan of the slots with higher lift cams.