Closed Chambered Heads

If you had 9.3:1 with open-chamber heads, you probably have domed pistons, at least slightly. If so, they can often be made into flat-tops with a lathe, as long as they're not hollow-domes such that the cut thins the piston crown too much. But if the block's been squared, the heads surfaced and all that, the final clearances might be such that you'll need thick composite head gaskets or cupped pistons to get your compression down to 10:1 or slightly lower. A big-duration cam will help reduce pumping pressure for 91 octane fuels without ping/knock. CA gas is arguably the worst in the US for these games incidently. The heads are fine (i assume they've been cut for a Boss valvetrain?). All you'll lose over 2V Aussie heads is some low-end torque due to your 4Vs having such gigantic ports. Great for top end stuff or stroker motors, though. As for an intake, Edelbrock's dual-plane Performer is the most poular unit on Panteras, matched to a 650-750 carb. The smaller the carb, the better the driveablity & fuel mileage, too. An open-plenum intake will make the top-end bias of your engine even more so IMHO.

> I have had a set of 71 Closed Chambered 4V heads redone and are going
> to replace my 73 Open Chambered 4V heads. My calculated CR was about
> 9.3:1 with the 1973 73cc heads, and I calculated that I will pick up
> a full point with the 63cc Closed Chambered version.

Are your pistons still stock? If so they are likely to be dished,
which will drop the compression. The open chamber plus dished
piston combination was listed at something like 8.7:1 compression.
Flat tops with open chamber heads were close to 9.0:1, maybe a bit
over.

> I have heard of everyone going to the 2V heads to gain compression.

Going to closed heads is a good way to raise compression. The
Aussie 2V heads and '70 to '71 U.S. 4V heads both have the closed
chamber. The Aussie 2V's are a bit smaller (maybe 4 cc's or so),
so will raise the compression a bit more. Not a big deal but I
chose to put the Aussies on my stock dished piston short block
to get the most compression without changing pistons.

> Am I crazy for reworking these heads. They came out absolutely
> gorgeous with 1 piece 2.25" Manley SS valves, Bronze guides,
> reworked bowls & runners, etc.

Not at all. Stock, the 4V heads out-flow the 2V's by a wide margin,
though the 2V's have better port velocity. You can make a good
running motor with either head. Which is best depends upon the
rest of the build and it's intended use. Also, remember that
heads are only part of the combination, the rest of the engine
needs to match the heads for an effective combination. BTW, the
2.25" is really only useful on a 0.060" and over-bore.

> Would a single plane intake work better than the Edelbrock Performer
> that I presently have??

Same as the heads, better depends upon what the rest of the combo
is and what you are looking for. The Blue Thunder high rise and
Holley Strip Dominator intakes will both make better power than
the Performer but are taller. The stock Ford 4V (in iron or aluminum)
is similar in height to a Performer but has larger 4V sized runners
which are worth some RPM on the top end. The Performer 4V runners
are smaller than a 4V but larger than a 2V port.

I don't care for either the Edelbrock Torker 4V or the Weiand
Xcelerator 4V intakes on 4V heads, though I do like the Weiand
Xcelerator 2V on 2V heads. I've not tried it but I wouldn't be
surprised if a Weiad Xcelerator 2V on 4V heads would work better
than either an Edelbrock Performer 4V or a Weiand Xcelerator 4V.
I say this because the Weiand Xcelerator 2V has an intermediate
port size, larger than 2V but smaller than 4V so should have
better port velocity than the usual 4V single plane intakes.

Dan Jones

Hi chris, i`m Lou. i live near you in Walworth, ny. I also put closed chambered heads on.Edelbrock manif. Contact me, say hi. Nice to have another Pantera near me.