>I have a 1974 Pantera with low mileage(14,000)and plan to have some
>engine modifications done. The engine/trans is going to be removed.
>One of my questions is what is the best distributor to replace the
>stock dual point(MDS Pro-Billet,Mallory Unilite or the Pro-Formance
>distributor sold by PRECISION PRO-FORMANCE). Second, should the valve
>springs be replaced. And last, the intake system question. What is
>the best carburetor/intake combination for this engine? A cam change
>is also a possibility.
>E-mail: ABrown1982@AOL.com
Sounds like you're in the same situation I was when I bought my 16,000
mile '74 Pantera. Your engine has large port, open chamber, 4V heads
and dished pistons, resulting in a dismal 8+:1 compression ratio. Also,
those heads have the stock Ford two piece (separate stem and head,
friction welded together) valves, retained by loose-fit keepers. They
are notorious for either slipping out of the keeper or popping the head
off the stem. The latter ruined my first 351C. Put a nice fist sized
hole in the block, twisted a connecting rod into a pretzel, ruined a
head, and generally destroyed the engine. It happened twice to a
friend before he wised up. Learn from our mistakes and install a set
of quality single piece stainless steel valves with single groove keepers.
You'll also want to replace the brittle umbrella valve seals. They have
a nasty habit of disintegrating and working their way to the oil pan
where they momentarily jam the oil pump, shearing or bending the pin that
locates the distributor gear. This retards the timing, causing the engine
to run sluggish and hot, if it runs at all.
Since you'll be pulling the heads and rebuilding them anyway, now is your
chance to address the compression issue. Install a set of Aussie 2V or
4V closed chamber heads. The Aussie 2V are a full 20 cc's smaller and
will boost you compression but still allow you to run 93 octane. They
4V quench chambers are a bit bigger than the Aussie 2V's but still
substantially smaller than the open chambers. Don't bother upgrading the
stock CJ cam unless you first increase the compression, otherwise you'll
just bleed off compresion you can't spare.
The best intake will depend on the heads chosen and how you intend to
use it. The Aussie 2V heads will like a Weiand Xcelerator 2V single
plane intake with a 700 CFM or so carb (I run a 735 CFM Holley on mine
and it'll pull 20 MPG on the highway). For closed chamber 4V's, a Blue
Thunder dual plane high rise (available with a flat carb pad just for
Panteras) or Holley Strip Dominator single plane are the best performance
picks. Both are tall though and may not fit under your stock screen.
The Weiand Xcelerator 2V will fit under a stock screen with a drop base air
cleaner and a 2 1/4" tall K&N filter element. The top just barely clears
the choke plate but it does clear. You can see mine at:
http://www.panteraplace.com/images/Dans%20351.jpg The Weiand Xcelerator 2V (p/n 7516) is a single plane intake with ports
that are larger than those of a 2V head. It comes essentially pre-ported
but requires the heads be match-ported to the intake. 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. Even though it's a single plane, it pulls smoothly from
low RPM, even with a Holley 735. I can lug it down in 5th gear to 1000 RPM
and it'll pull without protest.
Likewise, the preferred headers depend on the heads. The Hedman Pantera
headers available from PPC (Larry Stock) in Reno, have the proper flange
for the Aussie (and U.S.) 2V heads and have 1 3/4" diameter primaries and
a 2 1/4" diameter collector (fits the Pantera GTS mufflers and tail pipes).
Drive a second shear pin in the distributor gear or replace with a hardened
pin. If a little debris (see valve seals below) gets in the pump gears, it
can shear or bend the pin. This retards the timing which leads to sluggish
performance and overheating.
Clevelands are known for pumping a lot of oil to the top end and Panteras
with sticky tires can pull some decent lateral G's. A hard turn with the
revs up, can cause the oil in a stock pan to climb the side of the pan,
starving the bearings for oil. Not good. I run an Aviad gated and baffled
10 quart Pantera oil pan and pickup. The stock oil pump is fine to 6000
RPM or so. Above that you'll want to consider the oil restrictors.
A windage tray is always a good idea and a cheap source of a few extra HP.
Use a quality double row true roller timing chain set (Cloyes, SVO, or
similar). The stock gears are plastic coated aluminum and the chains are
known for stretching. Degree in the cam and mark true TDC on the balancer.
Paint a stripe on for a positive indication of balancer slip.
Clevelands use specific thermostat with a shoulder that fits in the brass
restrictor ring in the block (make sure it's there). Using a Windsor
thermostat (which the parts counter monkeys will give you half the time)
will lead to overheating because coolant will bypass the radiator. Don't
run an excessively cool thermostat. It won't make a difference in steady
state temperature but will slow warm-up time. I recommend the Robert Shaw
351C thermostat. It's quick acting and has bleed provisions.
Don't use the rubber intake manifold gasket end seals. Buy or make your
own from cork. I peen the block rails with a punch so the gasket won't
squeeze out while you're torquing it down. This also works well on valve
cover gaskets. Use Permatex 300 or a contact cement. Don't use RTV except
in the corners of the end rails and even there I prefer using the red/brown
Permatex. Retain the turkey pan unless the carb heat ports are blocked.
Since you're doing all this, you might as well install a cam kit with
new lifters, springs, machined (not stamped) retainers and locks. Specs
will depend on the heads chosen and RPM range desired.
Drive a second shear pin in the distributor gear or replace with a hardened
pin. If a little debris (see valve seals below) gets in the pump gears, it
can shear or bend the pin. This retards the timing which leads to sluggish
performance and overheating. Use a small cap distributor (MSD makes a nice
one but you'll also need to use their MSD-6AL ignition box and a tach adapter).
Large cap distributors may fit (or may not) but don't leave any room for
tilting the engine like you need to do when R&Ring the transaxle. Speaking of
transaxle, while it's out, safety wire the ring gear.
Dan Jones
