I have a 72 351c with the stock 4v heads with open chamber.I am in the proccess of building up the engine and am considering using 2v closed chamber heads with flat top pistons/comments please
thanks
Original Post
Replies sorted oldest to newest
The closed chamber 2V heads will bolt up to your 4V stuff perfectly & will add much low-end torque to the engine, making it more fun to drive around town. With the right porting, intake, cam/carb, you'll make MORE horsepower & torque than with the giant-valve 4-V heads. Your compression ratio w/flat-top pistons will approach or exceed 10:1 (too much for today's gas) unless you use thick head gaskets and/or cupped pistons.
Jack,so I can utilize the 4v intake & exhaust manifolds without port matching?Also do the 2v heads come with the 2.19 & 1.71 valves?
Have you ever used or added tryethellead for an octane booster as supplied by JACK PODELL?
Thanks so much for your input
Jim
Have you ever used or added tryethellead for an octane booster as supplied by JACK PODELL?
Thanks so much for your input
Jim
The 4V intake & exhaust need not be port matched unless you're intending to race it. As for running 4-V valves, No- for two reasons. First, they don't fit unless you have someone recut the seats and re-port the heads- a rather expensive endeavor. 2V heads take 2.08" intakes and 1.65" exhausts, slightly smaller than your 4-V valves. Second, stock valves are made in three pieces, welded together. Under stress, they break apart, utterly destroying the engine. I advocate using one-piece stainless valves.... and if the ad doesn't specifically SAY 'one piece', trust me- it ain't. Also, the stock split locks for each stock valve are what is known as 'multi-groove'. Under stress again, these locks sometimes release the valve stem, again destroying the engine. Use single-groove valves and matching split locks. Third, whatever cam you select should have a recommended valve spring to go with it, along with brand-new lifters. The remainder of your 4V parts can be re-used. As for octane boosters, I don't use or need them in my engines, so I'm unfamiliar with that product. Apparently, some do help but I believe its better to not engineer an engine with such high compression that a booster, or race gas, is necessary. The inconvenience isn't worth the possible extra power.
> The closed chamber 2V heads will bolt up to your 4V stuff perfectly
There will be port mismatches on the intake manifold and exhaust headers.
While not necessarily optimal, the 4V headers will work fine with 4V gaskets
though sometimes there can be a sealing problem. That said, I prefer the
Hedman Pantera headers that Larry Stock at PPC sells. They have the proper
size oval port flange for 2V heads, 1 3/4" diameter primaries and a 2 1/4"
diameter collector (fits the Pantera GTS style mufflers and tail pipes).
The intake manifold will have a bad port mismatch if you run a 4V intake
on a 2V head, Aussie or not. The 4V port is much larger than a 2V port and
shaped differently.
> The 4V intake & exhaust need not be port matched unless you're
> intending to race it.
Don't do it on the intake side. Going from a large diameter 4V intake
manifold port to a smaller 2V cylinder head port will put a big wall
all away around the port that the incoming fuel mixture must pass.
This will hurt flow, particularly at low RPM. A guy I know tried it
and could never get the thing to work well. Ended up pulling the
manifold off, selling it to me, and installing an Offy Dual Port.
Go with a dedicated 2V heads 4 barrel intake. There are a variety of
them but the best for a street driven Pantera is the Weiand Xcelerator 2V.
It's a single plane but pulls well down low and is worth a bunch over power
over an Edelbrock Performer. An example is a guy I know of who drag raced
his street Mustang. With a mild 351C-2V motor and 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. Be aware that you
must port match the Weiand Xcelerator 2V intake to the Aussie 2V heads.
The Weiand intake comes essentially pre-ported and has larger ports than
the 2V heads. If you use a turkey pan intake gasket (recommended unless
you've blocked off the heat risers), you'll need to trim the turkey pan
port openings to match, as well. I used a Dremel for that.
With a drop base air cleaner and a 2 1/4" tall K&N air filter, the Weiand
Xcelerator 2V will fit under a stock engine screen. You can see mine at:
http://www.panteraplace.com/Pantera%20Pics/Weiand%20intake.jpg
If you don't mind altering the screen or running without it, it will run
even better with a 1" or 2" tall spacer and a non-drop air cleaner base.
For more radical combos, there are several tall race intakes with 2V ports
made in Australia. The latest Parker Funnelweb looks good.
> & will add much low-end torque to the engine, making it more fun to
> drive around town.
I built the Aussie-headed 2V motor in my Pantera specifically to test
that theory. It was just a temporary motor and was destined to go in
a 1956 F-100 project truck I have, so I was looking for a lower RPM
emphasis. In my Pantera, it pulls strong from idle to 6000 rpm and
will pull 5th gear from 1000 RPM. Gets 20+ mpg on the highway, even
without vacuum advance. Nice rumble at idle, excellent throttle response,
docile around town, warms up quickly (something my other Cleveland with
bigger cam and blocked off heat riser does not do) and pulls cleanly
across the rev range. It doesn't pull as strong as my 4V headed motor
at higher RPM's but has better manners. When I pull it out in favor of
an A3-headed 408C stroker, it'll work just fine in the truck. Had I
been building it specifically for the Pantera, I would have used a
bigger solid lifter cam.
> With the right porting, intake, cam/carb, you'll make MORE horsepower &
> torquethan with the giant-valve 4-V heads.
You lose quite a bit of CFM with 2V heads, compared to 4V, but pick up
port velocity. 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.
> Also do the 2v heads come with the 2.19 & 1.71 valves?
2V sizes are 2.05" and 1.65". 4V sizes are 2.19" and 1.71". A lot
of people blindly install 4V valves in Aussie 2V heads but I don't
recommend it. You want the valve size to match the port size. The
larger 4V valves also hurt the transition at the short side radius.
> Your compression ratio w/flat-top pistons will approach or exceed 10:1
> (too much for today's gas) unless you use thick head gaskets and/or
> cupped pistons.
That's exactly the wrong thing to do and negates any benfit to using
the Aussie 2V heads. If you're going to drop the compression just
run open chamber 2V heads. The Aussie 2V heads have the exact same
porting as U.S. open chamber 351C-2V heads and the open chamber heads
actually flow a little better at low lift due to the unshrouded
valves. The performance benefit of Aussie 2V heads comes from being
able to run the higher compression ratio provided by a flat top piston
and the smaller quench chamber. The quench chambers allow a full point
more compression on the same octane fuel. For the quench effect to
work properly, the flat part of the piston must come very close to the
flat part of the chamber (the quench pad). Using a thick head gasket
of a dished piston ruins this. See the Keith Black piston web site
for details.
> Have you ever used or added tryethellead for an octane booster
You don't need it. If you polish the chambers and unshroud the valves
in the Aussie 2V heads and run a bit of cam, you can get along just
fine with quench heads and flat top pistons. At worst, you'll need to
dial out a little spark advance at lower RPM. No big deal.
> Second, stock valves are made in three pieces, welded together. Under
> stress, they break apart, utterly destroying the engine. I advocate
> using one-piece stainless valves.... and if the ad doesn't specifically
> SAY 'one piece', trust me- it ain't. Also, the stock split locks
> for each stock valve are what is known as 'multi-groove'.
Yup, the heads and stems are friction welded together. My first 351C
with standard bore block and quench 4V heads, popped the head off an
exhaust valve, shattered a piston, and punched a fist sized hole in
the block. Als the multi-groove keepers ae loose fit. If the head
doesn't pop off the stem, the stem will slip out of the keepers. I
suggest a quality one piece stainless steel valve. Look at the 6000
series Ferrea valves for 2V heads.
> I have a 72 351c with the stock 4v heads with open chamber. I am in the
> proccess of building up the engine and am considering using 2v closed
> chamber heads with flat top pistons/comments please
They'll work fine. A suggested build is:
- 700 to 780 CFM carb (exact CFM dependent upon cam chosen)
- Weiand Xcelerator 2V (p/n 7516)
- Aussie 2V closed chamber heads, fitted with 2.10" Ferrea F6155
intake valves, 1.65" Ferrea F6179 exhaust valves, bowl ported,
and unshrouded as described above, milled and drilled for
screw-in studs and guideplates
- 1.73:1 roller rocker arms (Crane gold race, Erson, Scorpion, Crower,
Comp etc... stay away from the cheapie import stuff)
- Speed Pro/TRW L2379F forged flat top pistons or Keith Black KB108
hypereutectic flat top pistons
- 10 quart Aviad road race Pantera oil pan
- stock volume Melling oil pump fitted with Moroso high pressure oil
pump spring
- Moroso (p/n 2205_ oil restrictor kit (drill 0.090" lifter gallery
restrictor to 0.110" or 0.125" if paranoid and running hydraulic lifters)
- drill oil feed to distributor gear
- stock 351C crank
- stock 351C rods with ARP rod bolts
- single pattern cam with 110 LSA. Duration and lift dependent upon
RPM desired. If you don't mind setting lash and a little loss in
torque below say 2500 RPM, a Comp 282S solid lifter cam will pull
hard past 6500 RPM. For milder applications, a hydraulic camshaft
220 to 230 degrees duration at 0.050", 110 LSA, and lift in the
0.530" to 0.560" range will work well.
- double roller timing chain set (Cloyes, SVO, JP, or similar quality item)
- Hedman 2V Pantera headers, 1 3/4" primaries into 2 1/4" collector
(to match GTS tailpipes... 2 1/2" or bigger would be better).
- MSD 6AL ignition box
- Robert Shaw 351C thermostat
- drive a second shear pin in the distributor gear or replace with
a hardened pin.
Dan Jones
There will be port mismatches on the intake manifold and exhaust headers.
While not necessarily optimal, the 4V headers will work fine with 4V gaskets
though sometimes there can be a sealing problem. That said, I prefer the
Hedman Pantera headers that Larry Stock at PPC sells. They have the proper
size oval port flange for 2V heads, 1 3/4" diameter primaries and a 2 1/4"
diameter collector (fits the Pantera GTS style mufflers and tail pipes).
The intake manifold will have a bad port mismatch if you run a 4V intake
on a 2V head, Aussie or not. The 4V port is much larger than a 2V port and
shaped differently.
> The 4V intake & exhaust need not be port matched unless you're
> intending to race it.
Don't do it on the intake side. Going from a large diameter 4V intake
manifold port to a smaller 2V cylinder head port will put a big wall
all away around the port that the incoming fuel mixture must pass.
This will hurt flow, particularly at low RPM. A guy I know tried it
and could never get the thing to work well. Ended up pulling the
manifold off, selling it to me, and installing an Offy Dual Port.
Go with a dedicated 2V heads 4 barrel intake. There are a variety of
them but the best for a street driven Pantera is the Weiand Xcelerator 2V.
It's a single plane but pulls well down low and is worth a bunch over power
over an Edelbrock Performer. An example is a guy I know of who drag raced
his street Mustang. With a mild 351C-2V motor and 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. Be aware that you
must port match the Weiand Xcelerator 2V intake to the Aussie 2V heads.
The Weiand intake comes essentially pre-ported and has larger ports than
the 2V heads. If you use a turkey pan intake gasket (recommended unless
you've blocked off the heat risers), you'll need to trim the turkey pan
port openings to match, as well. I used a Dremel for that.
With a drop base air cleaner and a 2 1/4" tall K&N air filter, the Weiand
Xcelerator 2V will fit under a stock engine screen. You can see mine at:
http://www.panteraplace.com/Pantera%20Pics/Weiand%20intake.jpg
If you don't mind altering the screen or running without it, it will run
even better with a 1" or 2" tall spacer and a non-drop air cleaner base.
For more radical combos, there are several tall race intakes with 2V ports
made in Australia. The latest Parker Funnelweb looks good.
> & will add much low-end torque to the engine, making it more fun to
> drive around town.
I built the Aussie-headed 2V motor in my Pantera specifically to test
that theory. It was just a temporary motor and was destined to go in
a 1956 F-100 project truck I have, so I was looking for a lower RPM
emphasis. In my Pantera, it pulls strong from idle to 6000 rpm and
will pull 5th gear from 1000 RPM. Gets 20+ mpg on the highway, even
without vacuum advance. Nice rumble at idle, excellent throttle response,
docile around town, warms up quickly (something my other Cleveland with
bigger cam and blocked off heat riser does not do) and pulls cleanly
across the rev range. It doesn't pull as strong as my 4V headed motor
at higher RPM's but has better manners. When I pull it out in favor of
an A3-headed 408C stroker, it'll work just fine in the truck. Had I
been building it specifically for the Pantera, I would have used a
bigger solid lifter cam.
> With the right porting, intake, cam/carb, you'll make MORE horsepower &
> torquethan with the giant-valve 4-V heads.
You lose quite a bit of CFM with 2V heads, compared to 4V, but pick up
port velocity. 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.
> Also do the 2v heads come with the 2.19 & 1.71 valves?
2V sizes are 2.05" and 1.65". 4V sizes are 2.19" and 1.71". A lot
of people blindly install 4V valves in Aussie 2V heads but I don't
recommend it. You want the valve size to match the port size. The
larger 4V valves also hurt the transition at the short side radius.
> Your compression ratio w/flat-top pistons will approach or exceed 10:1
> (too much for today's gas) unless you use thick head gaskets and/or
> cupped pistons.
That's exactly the wrong thing to do and negates any benfit to using
the Aussie 2V heads. If you're going to drop the compression just
run open chamber 2V heads. The Aussie 2V heads have the exact same
porting as U.S. open chamber 351C-2V heads and the open chamber heads
actually flow a little better at low lift due to the unshrouded
valves. The performance benefit of Aussie 2V heads comes from being
able to run the higher compression ratio provided by a flat top piston
and the smaller quench chamber. The quench chambers allow a full point
more compression on the same octane fuel. For the quench effect to
work properly, the flat part of the piston must come very close to the
flat part of the chamber (the quench pad). Using a thick head gasket
of a dished piston ruins this. See the Keith Black piston web site
for details.
> Have you ever used or added tryethellead for an octane booster
You don't need it. If you polish the chambers and unshroud the valves
in the Aussie 2V heads and run a bit of cam, you can get along just
fine with quench heads and flat top pistons. At worst, you'll need to
dial out a little spark advance at lower RPM. No big deal.
> Second, stock valves are made in three pieces, welded together. Under
> stress, they break apart, utterly destroying the engine. I advocate
> using one-piece stainless valves.... and if the ad doesn't specifically
> SAY 'one piece', trust me- it ain't. Also, the stock split locks
> for each stock valve are what is known as 'multi-groove'.
Yup, the heads and stems are friction welded together. My first 351C
with standard bore block and quench 4V heads, popped the head off an
exhaust valve, shattered a piston, and punched a fist sized hole in
the block. Als the multi-groove keepers ae loose fit. If the head
doesn't pop off the stem, the stem will slip out of the keepers. I
suggest a quality one piece stainless steel valve. Look at the 6000
series Ferrea valves for 2V heads.
> I have a 72 351c with the stock 4v heads with open chamber. I am in the
> proccess of building up the engine and am considering using 2v closed
> chamber heads with flat top pistons/comments please
They'll work fine. A suggested build is:
- 700 to 780 CFM carb (exact CFM dependent upon cam chosen)
- Weiand Xcelerator 2V (p/n 7516)
- Aussie 2V closed chamber heads, fitted with 2.10" Ferrea F6155
intake valves, 1.65" Ferrea F6179 exhaust valves, bowl ported,
and unshrouded as described above, milled and drilled for
screw-in studs and guideplates
- 1.73:1 roller rocker arms (Crane gold race, Erson, Scorpion, Crower,
Comp etc... stay away from the cheapie import stuff)
- Speed Pro/TRW L2379F forged flat top pistons or Keith Black KB108
hypereutectic flat top pistons
- 10 quart Aviad road race Pantera oil pan
- stock volume Melling oil pump fitted with Moroso high pressure oil
pump spring
- Moroso (p/n 2205_ oil restrictor kit (drill 0.090" lifter gallery
restrictor to 0.110" or 0.125" if paranoid and running hydraulic lifters)
- drill oil feed to distributor gear
- stock 351C crank
- stock 351C rods with ARP rod bolts
- single pattern cam with 110 LSA. Duration and lift dependent upon
RPM desired. If you don't mind setting lash and a little loss in
torque below say 2500 RPM, a Comp 282S solid lifter cam will pull
hard past 6500 RPM. For milder applications, a hydraulic camshaft
220 to 230 degrees duration at 0.050", 110 LSA, and lift in the
0.530" to 0.560" range will work well.
- double roller timing chain set (Cloyes, SVO, JP, or similar quality item)
- Hedman 2V Pantera headers, 1 3/4" primaries into 2 1/4" collector
(to match GTS tailpipes... 2 1/2" or bigger would be better).
- MSD 6AL ignition box
- Robert Shaw 351C thermostat
- drive a second shear pin in the distributor gear or replace with
a hardened pin.
Dan Jones