- The MPG "Stinger" exhaust port plates may be worthwhile for 4V heads if the
header doesn't turn down sharply at the port exit. The intakes port plates
may be more of a sealing and port match hassle than they are worth. Roush
and Marino Perna at Panteras East make intake port stuffers that go inside
the intake port. A thin layer of epoxy is used to bond the stuffer to the
pot and set screws are used to hold it in place.
- Quench heads (2V Aussie or early 4V) are the best for performance. They
allow higher compression for the same octane and make more power. Quench
heads have a flat area opposite the spark plug and an open area around the
plug. As the flat top piston rushes up toward the head, the area under the
flat reduces quicker than the area under the open part of the head. The
result is the mixture is forced at towards the plug. The resulting
turbulence evens out temperature and more completely burns the mixture.
More power, better fuel economy, and higher compression on the same octane.
If running a custom dished piston for forced induction or a stroker motor,
make sure there is a flat area under the quench pad. The best approach is
to have the pistons made with a reverse image of the combustion chamber.
- For street applications, flat top pistons (TRW forged or KB hypereutectic)
are generally used with the quench chambers for a compression ratio in the
10.5:1 range. Pay attention to the manufacturer's ring gap information you
plan to use nitrous.
- Quench heads run best with less spark advance (32-34 degrees) than open
chamber heads. The flame front has a longer distance to travel with open
chamber heads so they require more total advance, maybe 4 degrees or more
than a closed chamber head. A multi-strike ignition, like an MSD-6 series,
will allow an open chamber head to make peak power with less total advance.
- With an open plenum intake and some cam, I like the multi-strike ignitions
like the MSD-6AL (the -AL version comes with built-in rev limiter). They
improve cold start and low rpm performance. You can use any distributor
to trigger.
- Use a quality double row true roller timing chain set (J.P. Performance,
Cloyes, SVO, or similar). Degree in the cam and mark true TDC on the
balancer. Stay away from gimmick dampers (TCI Rattler, Fluidamper, etc.).
Stick with a stock or quality rubber elastomer type balancer (SVO/ATI,
ROMAC, etc.). Paint a stripe on for a positive indication of balancer slip.
- If you need new cam bearings, cut grooves on an old Cleveland cam to use
as a scraper or have a machine shop hone to fit. Cleveland cam bearings
were honed in the block by the factory and new ones are often too tight.
- For high rpm work with a solid lifter cam, consider the standard oiling
mods (galley restrictors and/or sleeved lifter bushings). For under 6500
rpm with a hydraulic cam, stock displacement
oil pump with a higher
pressure relief spring (or shimmed) is okay. High volume pumps increase
output at lower rpm where it's generally not needed, unnecessarily loading
the cam and distributor gears and wasting power. Use the SVO, ARP, or FPP
heavy duty
oil pump driveshaft. MPG Head Service (a.k.a. Cam Research)
makes a windage tray to fit the stock pan. The 351M/400 can type pickup
can be used to replace the 351C pickup. Make sure the pickup and the hole
in the mating surface align. Mellings has modifications that reduce
oil
pump pressure fluctuations that they claim leads to premature distributor
gear wear.
- Check the cam and distributor gears for proper contact pattern. You may
have to adjust the position of the gear on the distributor so that it
has the proper end play (make sure it doesn't rub hard on the block).
Also, it's worthwhile to pull the distributor after a few hundred miles to
check the wear pattern. There have been a rash of cam gear problems that
may be due to improperly machined cam cores. Make sure you use the proper
distributor gear material for the cam core or cam gear. Cast iron cores
require cast iron gears, steel gears require steel gears. Bronze is soft
(sacrificial) and can be used on both but doesn't last long. There are
new polymer and coated powdered metal distributor gears which may be
suitable. Make sure oil feed hole from front main bearing is open
(improperly installed cam bearings can block the oil feed passage to the
gear mesh). You can drill an 0.030" hole in the main oil gallery plug
just behind the gear mesh to pressure-oil the cam/distributor mesh.
Crane's hydraulic and solid roller cams are made from 8620 steel and
require a compatible steel (Crane makes a machined 8620 steel distributor
gear) or bronze distributor gear. Other's like Comp lists their hydraulic
roller cams and certain street solid roller profiles as being compatible
with OEM cast iron cam gears. Their -8 part number hydraulic and street
roller cam cores are austempered ductile iron. A surface treatment hardens
the cam lobes so they can run a roller lifter. Either a cast iron or cast
steel distributor gear is compatible with the -8 cores. Not compatible are
machined steel gears like the Crane 351C part which is made of 8620 steel,
the same as a solid roller cam core. OEM and Ford Motorsport steel gears
are cast steel and would work fine with the Comp street rollers but not
their race rollers. Unfortunately, Ford doesn't make one for a 351C.
Solid roller cams are usually ground on 8620 billet cores and require
bronze distributor gears which wear rapidly.
Mallory makes a special gear for their distributors that is made for
"austempered ductile iron billets" and "proferal billet" cams that is
supposed to be compatible with the Comp austempered iron cam cores.
As I understand it, the gear is heat-treated for compatibility.
Comp has recently introduced a polymer plastic gear but I think
they are only currently available for the SBF and SBC.
- Treat 2V and 4V engines as completely different when it comes to picking
components like cams, heads, and intakes. The primary difference between
2V and 4V heads lie in the ports.
- 4V heads have very large ports. The intake, though overly large for most
applications, is shaped decently enough. The exhaust is compromised to
clear the shock towers of early Mustangs and Cougars. The 4V exhaust
port has a hump then a sharp drop with an exaggerated area change. The
port exit area is very large but much of it is wasted and the flow velocity
low. The resulting intake to exhaust flow ratio isn't terrible but isn't
as good as it could be. Some builders recommend compensating by increasing
the exhaust duration and or lift, at least on milder engines. On higher
performance engines this may not be necessary and may even be detrimental.
4V heads also like a lot of lift and keep flowing more air past 0.600"
valve lift. The 4V exhaust port is sized for a 1 7/8" primary diameter
header.
- The best horsepower intake for the 4V heads is the Holley Strip Dominator.
It's a single plane and gives up low end torque but it's still smooth and
tractable. The Strip Dominator is currently out of production but can be
found at swap meets and on the 'net for $325 to $350. A close
second is the Blue Thunder high rise dual plane. It gives up a bit of top
end but has a better low end and cold weather start up. These go for
around $325 new and are available from the usual Pantera vendors. Both of
those intakes are quite tall. If hood clearance is an issue, then you're
best choices are a stock Ford intake or an Edelbrock Performer 4V (a.k.a.
F-351 4V). The Ford 4V intake were produced in iron or aluminum in square
or spreadbore (Motorcraft, not Qjet or Thermoquad) versions. The Offy Dual
Port is probably the best fuel economy, towing, intake for the 4V heads.