[Amc-list] V8 Cylinder Head Questions - 2nd Follow up ( read this one )

[Greg Taylor <amundaza@xxxxxxxxx>]

Hi all,
I am doing some work on my 1989 Grand Wagoneer engine and am considering swapping heads while I am at it. I need some feedback from the experts, please!

My Jeep has a stock remanned 360, which is probably 0.020 or 0.030 overbore. Reman company is unknown, but it has about 60,000 miles on the reman (11 years old ? done in 1997, 3 owners ago). I'm pulling the front timing cover to fix a coolant leak behind the fuel pump. I'll be installing a new Bull Tear front cover and nickel plated pump cover, double roller timing set, Bull tear matching cam/distributor gears, GM HEI, & a hi-flow water pump for this ?initial? build up. I?ll also be swapping from a 600-cfm 4160 to a 670-cfm 4150 Street Avenger.

I have been considering pulling the intake and heads while I'm at it and installing some 'built' heads I have. I have the 1979 304 (59 cc) heads I was building up for a 304 stroker turbo motor I was going to use in an AMC race car. I have ported and polished these heads (about 40 hours into them) and they are currently machined for CHEVY Milodon Megaflow 1.94 Int & 1.50 Exh. valves (they're smaller than stock 360, but have smaller stems and undercut stem in the runners). I am considering having them machined for larger Chevy valves, as Milodon makes much larger Megaflow valves.

How much larger can I go on a 360, with intake and exhaust valve size?

These 1979 304 heads also have the combustion chambers opened up as detailed in Performance American style, so they are probably about 62 cc's in size now. How much would this drop the stock 360's 8.4:1 compression? If it would drop too much, how much can I mill off the AMC heads, to bring compression back up? IF I could machine 0.100" off the heads, there are 0.100" longer Chevy valves that would make up the difference in valve height so that "theoretically" the pushrod length would not be affected.

My 1979 304 heads have been machined for 3/8" studs for the Harland Sharp roller rockers I plan to install.

How much would compression be raised if the 52 CC 70-71 304 heads were installed? Just curious. Stock 360 is 58 CC through 1984, from what I can find.

Last night I spoke with long time AMC club member (here in MI), Rick Jones, who built the 401 for my ?78 Cherokee Chief. He was telling me that he recalls that the later heads (like on my 1989 GW) were around 65 cc?s. Can anyone confirm this or have casting numbers available (my heads are still on the engine)? From the information I found online, the 360?s were 8.4:1 compression 1971(late)-1984 (58 cc heads). However, my 1989 GW has 8.25:1 compression. If this is due to the 65 cc heads (and probably piston combo), then I might be OK in swapping the ported/polished 62-cc 1979 304 heads I have modified. This would raise the 8.25:1 compression a bit (3 cc smaller heads). What do you all think? I would also be able to swap the 1970 304 52-cc heads as well, and raise compression up a lot (13 cc smaller heads).

Rick also told me that he has these 1970 304 heads on a 304 he built for torque and gas mileage. The engine turned out to be a real screamer with a small carter carb and the same intake I am running (see below). He?s getting 22+ MPG in his Javelin with it mated to an AX4 Jeep 2WD tranny.

As a side note, I am running the Holley Street Dominator intake. It?s a single plane intake with equal length runners. The intake runners are full size and then taper down to a smaller square port where they mate up to the head ports. It works well on the Jeep for added torque. I also had it on my 401 Rick built for me.

Lastly, this motor isn?t geared towards turning huge RPM?s. It?s a driver and occasional recreational off road FSJ here in MI (nothing crazy). I am simply wanting to get more power out of it and am building it to get better mileage, supplementing the gasoline with hydrogen-on-demand and water injection.

Thanks for the feedback, all.
   
  Greg :)

       
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