To my dismay I think my engine is Frankenstein. I have gotten a lot of great advice off of this web site, but unfortunatly most of it is contrary to the other. I have a 2 stamped on the top/font of both of my heads, making it (supposedly) a Cleveland. I have a higher block behind my destributer making it a Modified. I have a water-neck that isn't on the Manifold, you guessed it. . . Making it a Cleveland. My bolts on my bell housing are approx. 6" apart, not 3-1/2" apart, making it a Modified??? Cleveland Heads can fit a Modified, making it a Modicleve or a Fiedland. Would it be in the best interests of humanity to donate it to science so it may be disected and studied??. . . Perhaps.

FRANKENSTEIN LIVES!!!!!!!

Nate C. 1977 Ford 3/4 ton
351FR (Frankenstein)

 

The Ms also have the water neck on the block. You may have an M withe Cleveland heads (after all, they are the same). That would be my guess.

Nathan

 

I would agree with that about the heads on the modified

Mike

 

But don't get all excited. 2bbl Cleveland and 351M/400 heads are the same (and darn fine ones I think.) Remember a 351M is a 'modified' cleveland and the only modification is that it is based on a 400 block and uses a shortened stroke (compared to the 400, it's the same as the 351C)

So it is no surprise that many parts are interchangeable and you might easily confuse the two.

fordmando
70 F-100 Ranger XLT 400 C6
78 F-150 4x4 400 4 on floor
George

 

As a follow up in your list of 'pointers' the one stating the the water inlet on the block not on the manifold making it a 'Cleveland,' just as well could make it a 'Modified.' So of your pointers all but one point to Modified, so guess what it is.

fordmando
70 F-100 Ranger XLT 400 C6
78 F-150 4x4 400 4 on floor
George

 

You should check the exhauste valve clearance because that is one thing that is different between the M's and C's. the M's stock had a lower clearence, so if they put the heads on the M it would have a more effient gas ecape give you more horse power but less low-end torque.

 

I'd love to know how you figger that! Since the Ms and 2V Cs use the same valves and (non-adjustable) valvetrain you'd have to use different length pushrods and/or shim/grind valve stems to reduce valve clearance. Putting C heads on an M without changing pushrods wouldn't change anything.

 

White bread - So far I have not seen anyone mention the one nearly sure way to tell a 351C from a 351M. Check the transmission bolt pattern. The 351C has a small block bolt pattern while the 351M has a big block bolt pattern, as the names imply there will be a difference in how far apart the top bolts are. This is the quickest way I know of to tell them apart. Frankenstein was the scientist not the monster and the monster was just misunderstood, if you follow the Mel Brooks version.:->

 

>White bread - So far I have not seen anyone mention the one nearly sure way to tell a 351C from a 351M. Check the transmission bolt pattern. The 351C has a small block bolt pattern while the 351M has a big block bolt pattern, as the names imply there will be a difference in how far apart the top bolts are. This is the quickest way I know of to tell them apart. Frankenstein was the scientist not the monster and the monster was just misunderstood, if you follow the Mel Brooks
version.:->


Ughhh? Dosen't the original post mention that???

Dude, you got an M. There were no Clevelands in trucks. I realize it could have been swapped but that would mean trans as well. You've stated you have the big block bellhousing....it's a done deal.

 

or he can read the emission sticker, or check the vin code.

 

Well - actually, the 351C was available in the Ranchero - I've got a 351CJ in mine. Some may argue that a Ranchero is not a truck since it based on the Torino/Fairlane/Falcon/LTDII but Ford calls them a truck - and so does this site.

Tom

 

According to the Tom Monroe book the 351C 2bbl heads will interchange onto the 351M and 400. The 2bbl C heads are 76.2 cc's and the 351M and 400 heads are 78.4 cc's. The valve sizes are the same as mentioned above. The 2bbl C heads are supposed to raise the compression just a little bit. On the 75-80 years, 351M from 8.0:1 to 8.1:1 nothing to write home about, but a little. The 72-80 years, 400 from 8.4:1 to 8.6:1

Superdave

94 Ford Aerostar XL 3.0L
82 Ford F250 4x4 XLT,400 CID,C-6 A/T,8700lb GVWR. Black & Silver