> Has anyone out there used a set of Cleveland Aussi heads?
Yes, I have them on the 351C in my Pantera at the moment.
> If so, did you use them to replace 4V heads or 2V heads?
I replaced open chamber 4V heads. The engine in the Pantera came from
the factory with open chamber heads and dished pistons so the compression
was very low. I went with the Aussie 2V closed chamber heads primarily
to get the compression up. The Aussie heads have a quench chamber but
it is a little smaller than a U.S. chamber since the 2V valves are smaller.
IIRC, my heads were 57 cc versus 64 cc's or so for U.S. 4V closed chamber
The heads are only part of the equation. You'll need to swap intake
manifolds and it would be best to use 2V headers with 1 3/4" primaries
(4V's are usually 1 7/8" or larger) but you can use 4V headers in a
pinch. A single pattern cam is probably better suited to the 2V heads
and I'd recommend 110 LSA for your basic street application (a lot of
4V cams are ground on 108 lobes).
My engine was only meant to reside temporarily in the Pantera while I
gathered parts and saved $$$ to do a big stroker engine. The ultimate
home for the engine was to be in my '56 F100 pickup truck project so
I cammed it milder (218/222, 110 LSA, 0.530" lift) than I normally would.
The intake manifold is a Weiand Xcelerator 2V single plane open plenum
with a 735 Holley on top. 1 3/4" Hedman Pantera headers were used,
along with a MSD-6AL ignition box. The heads were home ported (bowls
and intake port match). I did up a similar combo for another Pantera
but used a Comp 282S solid lifter cam and the owner loves it.
A word about the Weiand X-Celerator 2V (p/n 7516). The ports are larger
than the 2V head ports. It's essentially a pre-ported intake and requires
the heads be match ported to the intake. Also note that when Holley
purchased Weiand, they screwed around with the intake manifold names and
started calling the Xcelerator a Stealth, a name that had been reserved
for high rise dual planes. Use the p/n above if there's any confusion.
Kid Vishus has also used the Weaind intake mentioned he tested both the
Edelbrock Performer 2V and the Weiand Xcelerator 2V on his street Mustang
which had a mild 351C with open chamber 2V heads. With an Edelbrock
Performer 2V, it ran 14.80s shifting at 5500 rpm. Switching to the Weiand
Xcelerator 2V, with no other changes, put the car into the 13.20's.
> What are your impressions of torque, throttle response, etc? Would you
> recommemd them? I am thinking of swapping my 4V open heads for a set of
> 2V heads, but I am intrigued by the Aussi heads.
Throttle response and torque are quite good. With the combo described
above, I can put it in 5th gear and it will pull smoothly from just off
idle, say 1000 rpm or so. Excellent throttle response and pulls to 6000
RPM (limited primarily by the mild cam) and gets 20 mpg on the highway
with only mechanical advance (no vacuum advance).
I have closed chamber 4V's on my other Cleveland and they come on like a
light switch at 3000 RPM or so. The Aussies don't do that and pull
smoothly across the rev range but don't pull as well up top. This is to
be expected since you lose quite a bit of CFM with 2V heads, compared to
4V, but pick up port velocity. See flow info below. To get some of the
CFM back, I suggest the following. Use oversize 2.1" diameter intake
valves (available from Ferrea), 1.65" diameter (same as stock 2V) exhaust
valves with undercut stems and a 30 degree backcut (to aid low lift flow).
Do a good bowl port (blend the area under the valve seats, narrow the
guides, and port match the intake ports to the Weiand Xcelerator 2V intake
manifold. It's also important to unshroud the valves as the Aussie
chambers have very tight chambers.
I'd pass on Powerheads. A couple of guys in the Pantera club tried them
and had trouble. The first had mismatched heads (different CC's) and
the second had the wrong springs installed.
Dave Williams had a set of Aussie 2V and a set of 4V heads flowed at Kuntz
and Company. Here are the results and Dave's comments:
flow at 28" water, in CFM
351C-4V Aussie 2V
lift int exh int exh(1.71")
.050 49 47 45 38
.100 76 66 70 63
.150 112 71 98 85
.200 143 111 130 98
.250 175 126 161 112
.300 206 141 183 126
.350 233 152 195 140
.400 251 160 198 151
.500 269 175 206 166
.600 282 183 208 174
.700 292 186 209 171
The 4V heads had the stock single-angle valve job and 5/16" Manley valves.
The exhaust figures are with an MPG port plate. The 2V heads had 2.06/1.71
SSI valves, the exhaust is 4V size, on a standard 3-angle seat. There was
a little unshrouding on the wall side due to the stone diameter.
The 4V head comes on like gangbusters very early; not what rumor had it.
The 2V head doesn't match the 4V anywhere, and past .300" lift it lags badly.
Also notice how oddly flat the flow curve is past that point. Just looking
at the port doesn't show any particular obstruction that might be a choke
point. Jim Kuntz said the flow figures were about right for stock, unported
Cleveland heads when I asked about the odd results. He also said back
cutting the valves and a good three-angle seat would usually pick up
another 30CFM on a Cleveland. His flow bench operator also mentioned
that the naked ports usually flow 20-30CFM less than a port with
They used an SF-600 with a 4.25" cylinder spacer. When I asked about
that, they said they used the 4.25" spacer for everything. I think it
probably throws the figures off, but as far as I know most people do it
the same way.