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On a couple of occasions recently, on the topic of Ford motor choices for the Pantera, I have mentioned the existance of a rare 400 engine block that has the Windsor/Cleveland bell housing bolt pattern. This block is referred to as the fmx block because it was cast to allow use of fmx transmissions on the 400 block. This block was cast only in 1973 and has a block number of D3AE-B.

I saw this picture today on another forum I hang out at, I 've seen it many times, but today it struck me that some one might find this picture interesting, it shows the unique feature of this block & how to identify it.

Your "block head" friend on the PIBB, George


Images (1)
  • 73_fmx_block
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I don't really know why Ford cast the fmx block in 1973 only. I can only guess they had an excess of Windsor/Cleveland fmx trannys and decided to utilize them rather than dump them.

The engine went into mid size & full size Ford products such as LTDs, Thunderbirds, Torinos, and Mercury products such as Marquis, Montereys & Montegos. Knoweledgable Ford folks keep an eye out for them, it's been 30 years, they are fairly well weeded out, but they do turn up now and then. So I would say it is difficult to find one, but not impossible.

The only issue is the ease of swapping a 400 in place of a Windsor/Cleveland, with this block, there is no need to swap trannies or adapt a bell housing.

I agree Michael, that big cavity in the back of the block is "funky".

Your funky friend on the PIBB, George

correct! lots of room for stroking with this block, since the deck height is 1.1" higher than a Cleveland's. The lower end is wide enough, and the cam shaft high enough, that there is no consideration of the counterweights hitting the block or cam. Currently the longest stroke crank available is 4.25" (it uses Windsor crankshafts). with the stock 6.58" rod, that gives you a very acceptable rod length to stroke ratio of 1.55 to 1, and leaves 1.595" "compression height", the distance between the center of the wrist pin & the top of the piston. This indicates how much room there will be for the ring package, and anything greater than 1.250" is plenty.

Just like the engine Gary is building, a 0.030" overbore on the cylinders plus the 4.25" stroke crankshaft results in 434 cubic inches. Rock n Roll!

your stroked friend on the PIBB, George
It's a drop in Michael, the main & rod journals are the same dimensions & even the counterweights on the balancer & flywheel are the same (28 oz).

Thats how Ford made the 351M! They dropped 351W cranks in 400 blocks & used different pistons with 0.300" additional compression height.

"dropping in" on my friends on the PIBB, George
As with anything there are issues. Nothing that can not be worked around. One unforseen issue will be things like timing chain gears. This is the guy building my 400 stroker:
If you find a 400 he can work out those issues for you though. There are 2 new heads to work from. One being CHI and the other being Edelbrock. CHI flow better at high rpm. At a lower rpm the edelbrock flow a minute better but very close. Tim is putting the CHI on mine but he ground the heads to get the airflow back up at the lower rpm. One issue with the heads is intake. You will beable to use other intakes with the edelbrock but only CHI intake with the CHI heads.

They say the engine webbing is weak if you want to run over 900hp and over 7-8000 rpm and needs to be re-enforced. I have heard guys say that is why they won't run that engine. I just thought you should know incase you plan on running your Pantera in a top fuel dragster class. LOL.

top fuel! LOL

yeah, there are structural issues with the block, it was cast in 2 different foundries, both the Cleveland foundry & the Michigan Casting Center, the blocks cast in the Michigan Casting Center before March 1977 have a problem with cracking in the lifter valley 1" above the lifter bores. Plus those are some very tall unsupported cylinder bores that would make this block a good candidate for a half fill with hard block.

Actually Gary, any Cleveland cylinder head will fit the 400, and any Cleveland intake can be adapted with spacers. CHI, Edelbrock and AFD all make an alloy 351C 2V head. You used the CHI 3V head, hence the necessity to use their intake manifold. 4V heads, high port Motorsport heads, can be used as well. All of the aftermarket intake manifolds designed specifically for the tall 400 block have Cleveland 2V size runners.

Ron to answer your question as best as I can, any 1973 Ford or Mercury sedan or station wagon equipped with a 400 AND the fmx automatic transmission is a possible donor for the fmx block.

Your top fuel friend on the PIBB, George
Last edited by George P

I'm in the same camp as you: "Keep the engine below the engine screen and out of the rear view mirror!"

I haven't seen a 400 in a Pantera yet. My educated guess is that if the oem 351C intake were used, without any spacer between the carb and manifold, then the carb would sit approximately the same height as the carb on the '73 - '74 351C, which had an egr plate between the carb & manifold. If so, the engine screen from the Pantera L should be able to clear an air filter assembly, so long as the filter assembly weren't too tall. It would be a tight fit. The screen on my L rubbed the chrome lid of the oem air filter assembly on my 100% stock motor.

Hope all is well in Fresno, enjoy the weekend!

Your friend on the PIBB, George
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