"L" engine

The 5 mph bumpers and the low emissions motor were mandated by the US government for the 1973 sales year, and so I personally doubt the earlier motor was mixed with the 5 mph bumpers. But anything is possible.

'72 verses '73 motor

In terms of desirability, the emission motor is not a bad motor.

The version of the 351C installed in the "L" differed from the engine that preceded it in the following ways:

(1) open combustion chambers volume increased by 3 cc's
(2) 8cc dish in the piston domes
(3) 2V sized valves (2.05" intake, 1.65" exhaust)
(4) exhaust gas recirculation
(5) camshaft timing retarded 4 degrees
(6) compression ratio decreased from 8.8:1 to 8.0:1
(7) rated net bhp dropped from 280 to 264.

This motor was referred to as a 351C-4V, however it retained all the good hi performance parts of the motor that preceded, which was referred to as a 351 Cobra Jet. Both motors had the same engine code, "Q", and are often referred to jointly as Q code motors. Both motors are superior to the first 351C 4V, the one with the closed combustion chambers. They are superior because they were equipped with larger 4 barrel carburetors, 4 bolt main bearing caps, dual point distributors, "cobra jet" high lift camshafts, larger crankshaft dampeners.

Both Q code motors are thought of as low compression motors because both had open combusion chamber cylinder heads. The '70-'71 351C 4V motor had closed combustion chamber cylinder heads, and a compression ratio of about nominal 9.7:1. Although all of Ford's literature claimed the compression ratio was 10.7:1, this is not the case.

Dual pod verses single pod dashboards

The "single pod" dash does not define a "L" Pantera, the bumpers and emissions motor do. The single pod dash is simply just another one of many running changes that were incorporated into the Pantera during its '71 to '74 production history. This is not necessarily mixing and matching. The later dash was less expensive to produce, but at the same time it was also more ergonomic.

George

George, my new engine is a cobra jet spec, but I kept the closed chamber heads off my old engine. Can I just bolt on my old heads without doing nothing else and have an engine that runs on premium and makes almost as much power as my old engine did?? Or do I have to change a whole bunch of other stuff too?????

DeTom

that change alone will be worth about 2 to 7 bhp. I don't think its worth it. However the compression ratio increase is often felt in the seat of the pants as a boost in low rpm response, and eveybody likes that.

"IF" you were changing the camshaft to a hotter grind, and the camshaft manufacturer called for a motor with a compression ratio in the 9.5:1 range, then yes bolting on the cc heads would be called for.

Otherwise, what you need to do with your motor is zero deck the block, install fordged flat tops pistons. This gets you about 10.0:1 compression ratio. If the compression ratio needs to be adjusted lower for the cam & fuel you've selected, then dishes should be machined in the tops of the pistons that mimick the shape of the combustion chamber in the cylinder head (i.e. we're talking custom pistons).

All of this work is aimed at maximizing squish, which is the real power maker, more so than just a compression increase. Instead of 2 to 7 bhp, the gain realized by this work will be on the order of 30 bhp or more, depending upon the state of tune of your motor.

cowboy from hell

Two thousand bucks to get 30 horsepower?? Dang the whole engine only costed 3000. It hardly seems worth doing. Seven horsepower is like a glass pack or K&N filter. Man that is dissapointing.

Pantera's are like a box of chocolates, never know what you're going to get . . . .

The heads on the CJ that came out of my '74 wreck had large 4v valves. They were supposed to have 2v sized valves.

Then again the interior of the car was all Pre L

Thanks George, when you said the cobra jet spec cam was better than the CC head cam, I got a little excited thinking I could save a bunch of money and get more zip back into the old car before it was time for the big rebuild. Now it looks like it will just have to wait until thecar gets its restoration in about ten years or so.
I liked the acceleration and sound of my old motor better, but using octane boost and not starting when hot was a real drag. I am thinking running premium pump gas would make a nice comprimise. So what I will do is save up, since I got to buy new valves for my CC heads anyways, and get the most radical hydraulic roller cam that Crane makes, along with roller rockers and such and maybe then it will feel like my good old motor.

Dennis, I thought the Cobra Jet always has the larger 4V valves.
It's after the Cobra Jet, from '73 that the valves are 2v sized.

George, am I correct?

quote:

Originally posted by Rapier:
...George, am I correct?...

The '70 - '71 M code motor was called a 351C 4V.

The late '71 - '72 Q code motor was called a 351 Cobra Jet

The '73 - '74 Q code motor was called a 351C 4V, even though in essence it was a Cobra Jet spec motor with tweeks for exhaust emissions.

The '73 - '74 motor was installed in all the US Panteras (the L models). Technically the motor in Dennis' L should have the small valves.

There are 3 explanations:

(1) Ford mixed and matched motor parts (installed 4V valves in the '73 casting, or installed '72 heads on a '73/'74 short block)
(2) A previous owner has swapped heads
(3) A previous machine shop installed larger valves during the course of a valve job (intentionally for performance, or unintentionally, not knowing the '73 heads actually required the smaller valves)

cowboy from hell

There were so many odd things with the wrecked '74 (early interior, large valve heads, early front spindles etc.) that I tend to think that it was put together with all the spare parts that were sitting around in the factory.