[DeTomaso] Cylinder Head Style (application)
JDeRyke at aol.com
JDeRyke at aol.com
Wed Aug 6 13:16:56 EDT 2008
In a message dated 8/6/08 1:52:40 AM, bianchito at hotmail.com writes:
> ....varieties such as Trick Flow Twisted Wedge, Trick Flow Track
> Heat...knowing less than nothing on engines, I wonder...what does it refer to and whats
> the head style on the Pantera. Was it the same on all cars? My 71 (4V) was
> it different than the 72's smog limited cars??
>
All the strange named heads above are aftermarket, most of which didn't even
exist when the 351-Clevelad was in production. Most are Windsor-type with
straight valves, not canted. They will fit a Cleveland, just as a stock Windsor
head will fit, with some adaption. They all have smaller valves than even a 2V
head.
The 351C had staggered valves, done so much larger valves could be added than
were possible with straight-stem valves. There were two varieties: a '4V'
with extremely large valves and ports to match, and a '2V' with smaller valves
and ports to match. There were also two combustion chambers possible, on both
4-V and 2-V heads: a 'closed' chamber and an 'open' chamber. The closed chamber
had higher compression and much better mixing while the open one was like a
bowl. It generated less smog but also less horsepower. A stock '71 4-V head may
have been either a closed chamber or an open chamber. And after all, its been
37 years and who knows how many 'tuners' have dug into that engine and changed
things? Without removing the heads and looking at the combustion chambers, it
is impossible to tell externally which you have. I suggest simply enjoying
the car as is until its time for a rebuild.
There are a few weak spots you should address soon, though:
1)- 351-C cam timing chains wear out very fast due to the huge, heavy valves
and the high rpms the engine will run. A double roller chain similar to a
motorcycle drive chain as a replacement will be stronger and last longer. Both
sprockets will change with the different type chain.
2)- At the bottom of the distributor is a cast iron gear held on with a pin
made of a coil of thin steel. This will break. Replace it with a 'roll pin'
that is made of much thicker steel with a slot down one side; most of us add a
second smaller pin inside the first for added insurance. Or add a steel dowl pin
made of drill rod, pressed in.
3)- the 7" long hexagonal driveshaft between the bottom of the distributor
and the oil pump is soft steel and will twist, then break once you've fixed #2
weak spot (above). An aftermarket oil pump driveshaft made of 4130-steel is
less than $15 USD and fixes the last common weak spot. Many U.S Panteras had all
these extra parts added by owners over the years, along with a fully baffled
10-quart oil pan, needed due to the very high cornering capabilities of a
Pantera. Good luck with your machine- J Deryke
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