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Author
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Topic: 351C / 351M Quick Identifications
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skips69
Gearhead Posts: 287
From: Catlin, IL USA
Registered: Mar 2001
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posted 01-03-2003 05:31 PM
   
My pops just bought a 72' Mach 1 to keep his other Mach 1 (a 73') company in the garage. Anyway, the prior owner states this was formally a drag car that ran high 13's in the quarter, and when the original 351C blew in it, he replaced it with it's current 351M from Jasper engines. He is very sure this is an "M" motor and not a Cleveland. It looks like a Cleveland to me, and it has a factory cast iron 4V intake on it. I don't recall any "truck motor" 351 M's coming with a factory 4 bbl, and didn't think an intake from a 351C would interchange with a 351M, or vice versa. Any way to tell by looking at some things on the engine without tearing it down? As a side note, he also threw in the "bad" 351C. I can't wait to tear it down and see what it has in it - there is a big Weiand tunnel ram on top with 2 Holley double pumpers. The car looks bone stock except the long studs sticking out on the rear wheels. The guy stated that it still has the "built" C6 installed and also a 4:11 POSI 9" rear. We just got it home, haven't even tried to drive it yet, it was that good of a deal. Thanks for any input!
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SteveLaRiviere
Administrator Posts: 34763
From: Saco, Maine
Registered: May 99
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posted 01-03-2003 06:06 PM
The most obvious is check the top two bolts of the bellhousing. The 351M uses the larger big block bellhousing. Ask the guy if he had to change tranny to make it fit. You are correct also that all 351M/400s were two barrels and the manifolds don't interchange. {Also, the casting number on the right side of the block above the starter will ID it if you can see it.}
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'70 Mustang Mach 1 - '72 Mustang Sprint - '94 F-150 Remember our sponsors, Mustangs Plus, NPD, Osborn Reproductions, and MyFordPerformance.com. [This message has been edited by SteveLaRiviere (edited 01-03-2003).]
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dhearn
Gearhead Posts: 227
From: Owenton Ky,USA
Registered: Nov 2000
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posted 01-03-2003 06:23 PM
at risk of showing my ignorance......(ok you dont have say it haha) aint the 351m block and the 351c block interchangeable except for the bellhousing.?------------------
1969 MACH 1
THE FEEL AND SOUND OF A FORD V-8 IS ALL THE DRUGS A MAN NEEDS
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SteveLaRiviere
Administrator Posts: 34763
From: Saco, Maine
Registered: May 99
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posted 01-03-2003 06:25 PM
Nope, two different animals. The 351M has the same taller deck the 400 has. The crank has larger journals and it has longer rods.------------------
'70 Mustang Mach 1 - '72 Mustang Sprint - '94 F-150 Remember our sponsors, Mustangs Plus, NPD, Osborn Reproductions, and MyFordPerformance.com.
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clevelandstyle
Gearhead Posts: 717
From: Connersville, IN
Registered: Jul 2001
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posted 01-03-2003 10:22 PM
Where am I when deals like this are going down? 
It sounds like it could be a Cleveland to me. Also, look on the front, top of the head, next to the valve covers and see if it has a 2 or a 4. Those would be Cleveland heads. If there is no number, it's a M head. ------------------
Ben
Grabber Green '70 Mach I 351C 4V
Robbin Egg Blue '79 Fairmont 351C 4V
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DidgeyTrucker
Gearhead Posts: 1100
From: Greenbrier, TN USA
Registered: Oct 99
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posted 01-03-2003 10:36 PM
If there is no number in the corner of the heads they are 400 heads. 351M heads have an "M" - so Ford dealership mechanics could ID the engine for maintenance. If the heads have 4V size ports and no number in the corner, they are Boss 302 heads!
The 351C block has motor mount bosses identical to a 302 (two bosses). The 351M/400 block has three bosses on the side, and the entire mount system would have to be "rigged" since the 351M was not available in the Mustang chassis.Tracy ------------------
Tracy M&M #245
MAC OS9
1956 F-100 Panel w/429
(3.50 9")
1966 F-100 SWB w/351C
(3.25 9" - 3.70 posi for Saturday nights)
Music City F-100's,
1965 GT-350 S/C
(2.78 1st & 3.70 TracLok 9")
Music City Mustang Club
Don't focus on the destination....make the JOURNEY the adventure
Visit my Web site: DidgeyTrucker's Website
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Hemikiller
Gearhead Posts: 404
From: Clinton, CT
Registered: Feb 2002
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posted 01-04-2003 09:24 AM
In addition to all of the items mentioned above, the most obvious and easily seen characteristic of a 351M / 400 block is a 1" tall "wall" of cast iron on the block, on the drivers side of the distributor mounting area running fore to aft. If there is no vertical wall here, then it's a Cleveland block.
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cobravenom71
Gearhead Posts: 808
From: Kissimee, Fl USA
Registered: Aug 2002
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posted 01-04-2003 02:38 PM
This may also seem like a rookie question, but there are some motors that also confuse me: What is the difference between a 351M, a 351M/400 and a 400. And is the 351M/400 considered to have 351 or 400 cubic inches.
Are any of these any good for performance applications?
My '76 Torino has the 351M/400(I'm pretty sure. The cars' in storage and can't check right now), and it is a totally gutless pig. I put a Holley 4-barrell manifold and carb on it about 20 years ago, and it only helped marginally.(I kept the perfectly good stock intake stuff too.).From that experience, I have a bad opinion of the 351M/400's.
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SteveLaRiviere
Administrator Posts: 34763
From: Saco, Maine
Registered: May 99
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posted 01-04-2003 06:45 PM
quote:
Originally posted by cobravenom71:
This may also seem like a rookie question, but there are some motors that also confuse me: What is the difference between a 351M, a 351M/400 and a 400. And is the 351M/400 considered to have 351 or 400 cubic inches.
There is no 351M/400 engine, that's just the way the 351M or the 400 engine is listed in catalogs or manuals. ------------------
'70 Mustang Mach 1 - '72 Mustang Sprint - '94 F-150 Remember our sponsors, Mustangs Plus, NPD, Osborn Reproductions, and MyFordPerformance.com.
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68F100
Gearhead Posts: 2081
From: Fort Madison, Iowa USA - United We Stand
Registered: Oct 99
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posted 01-04-2003 08:40 PM
If I'm wrong, let me know. There are 351M and 400M engines. Two different motors. Same family right? I always thought that they were the same block with different displacement. Most people think they are dogs and they don't have much as far as go fast goodies for them. I have a 400M in my 77 F-150 and it knocks in the lower end(which I've heard most of them have that problem) but it will still lay a black mark. I'm not driving it anymore because the c6 leaks tranny fluid faster than I can dump it in. Oh well, it's just a parts truck.
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cobravenom71
Gearhead Posts: 808
From: Kissimee, Fl USA
Registered: Aug 2002
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posted 01-04-2003 09:48 PM
Steve, I went out and checked the engine tag on my 79' Mk-V(attached to the valve-cover), and this is exactly what is printd on it on the top line: 5.8M/6.6 (351M/400) "D" (2x124) Would that not be considered a 351M/400 engine? Does this engine have 351, or 400 cubes?
And, are there also just 351Ms and 400s?
And what is the difference between all these motors?
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skips69
Gearhead Posts: 287
From: Catlin, IL USA
Registered: Mar 2001
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posted 01-05-2003 07:58 AM
The only difference between the 351M and 400 is that the 400 has a different crankshaft - longer stroke, and the 400 has different pistons - due to the different crankshaft. The block, heads, distributor, intake, connecting rods, oil pan, etc, etc are all the same. I looked for a true 400 to put into my 1979 F150 a few years ago to replace the tired 351M, and that's what I came up with back then. There aren't any aftermarket goodies for this engine outside of the Edlebrock intake and an aftermarket carb (and some ignition upgrades). They never came with compression ratios higher than 8.1:1 or something like that, so any higher compression pistons will have to be custom made ($$$) - From my experience, the difference between a 351M and 400 is minimal, there's a little more torque in the 400 is all.
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Hemikiller
Gearhead Posts: 404
From: Clinton, CT
Registered: Feb 2002
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posted 01-05-2003 08:25 AM
CV, Ford got cheap and printed the tune up/emission specs on the same tag. Guess they knew thet had a real winner, huh? You have to decode the VIN to figure which motor you have. It'll be a 351M or a 400M. A 400 is good donor motor for a 351C stroker crank, that's about it......
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kid vishus
Gearhead Posts: 4923
From: middle of NC
Registered: Oct 2000
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posted 01-05-2003 10:17 AM
quote:
Originally posted by skips69:
They never came with compression ratios higher than 8.1:1 or something like that, so any higher compression pistons will have to be custom made ($$$)
Not true about custom pistons. You can have the small ends of the rods bushed for the cleveland pinsize and use cleveland pistons. That's really not that big of a deal. Truthfully, a 400 with some domed cleveland pistons, a good solid camshaft, and 4v cleveland heads should run pretty hard. I also believe that someone makes spacers that go between the head and the intake so a cleveland intake can be used on a 400. That is if you were instistant upon running a 400.  [This message has been edited by kid vishus (edited 01-05-2003).]
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skips69
Gearhead Posts: 287
From: Catlin, IL USA
Registered: Mar 2001
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posted 01-05-2003 10:25 AM
That is true about the Cleveland pistons working with the connecting rods drilled out and Cleveland pins being used, had forgotten about that. These are fine engines for trucks, but if doing a Mustang, you would certainly be saving some money by locating a Windsor or Cleveland to build up. I am sure that the engine in this car (my original topic starter) is a 351C, don't know why the guy stated (quite a few times) that it was an M motor - not a good selling point if shopping for Mustangs. It was an unreal deal though either way, very nice find.
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Moneymaker
Administrator Posts: 19964
From: Lyons, IL, USA
Registered: May 99
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posted 01-05-2003 12:20 PM
351M/400 is FoMoCo's way of referancing the engine family. GM and Mopig does the same thing on their spec ID tags.
Some are on radiator core supports and and some are on valve covers.
GM 5.0, 5.7
Mopig 5.2, 5.9------------------
Alex Denysenko
Co-Administrator and Moderator NHRA/IHRA/SRA member and licensed Superstock driver
MCA member# 53321
NHRA and IHRA SS/LA National Record Holder '00,'01,'02,&'03
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Professional Manwhore
The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
Quote #3: "If you can't run with the big dogs, stay on the porch!"
www.moneymakerracing.com
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SteveLaRiviere
Administrator Posts: 34763
From: Saco, Maine
Registered: May 99
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posted 01-05-2003 07:57 PM
quote:
Originally posted by cobravenom71:
Steve, I went out and checked the engine tag on my 79' Mk-V(attached to the valve-cover), and this is exactly what is printd on it on the top line: 5.8M/6.6 (351M/400) "D" (2x124) Would that not be considered a 351M/400 engine? Does this engine have 351, or 400 cubes?
And, are there also just 351Ms and 400s?
And what is the difference between all these motors?
That just tells you they are using the same tag for two different engines. {The 351M and the 400.} The stroke of the crank is the only difference between the two engines.
------------------
'70 Mustang Mach 1 - '72 Mustang Sprint - '94 F-150 Remember our sponsors, Mustangs Plus, NPD, Osborn Reproductions, and MyFordPerformance.com.
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cobravenom71
Gearhead Posts: 808
From: Kissimee, Fl USA
Registered: Aug 2002
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posted 01-05-2003 10:12 PM
So how is the car owner supposed to tell what engine is in his car? According to the engine tag it could be either a 351M or a 400, right? Seems to me there should be a definitive designation somewhere without having to check the VIN#.
The VIN code on mine is 'S', which denotes a 400 2-V. It also has a 2.47/1 rear gear,8.0/1 compression, 159 HP, and 315 lbs. of torque. With this combo in a 4800 lb. car, you can almost run faster than this car can drive. But hey, at least it still gets crappy gas mileage!
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67coupe
Gearhead Posts: 418
From: dallas NC usa
Registered: Nov 2000
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posted 01-05-2003 10:19 PM
not sure bout all of them but the sticker on my truck has a line farther down that cid and says what the motor actually is and on the top it says 351m/400. so mayby this will help some of yall out   ------------------
Josh
67 coupe with 351c
8.41 in the 1/8
1.90 60'
at 82.03 mph
94 Explorer
30 model A currently rustbucket
in process 67 convt with efi 5.0 and t5
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Moneymaker
Administrator Posts: 19964
From: Lyons, IL, USA
Registered: May 99
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posted 01-05-2003 10:27 PM
Technically CV, as of 1975 and the advent of Gov't mandated emissiom controls, you aren't supposed to know. Everything is in code designed for only the dealer to decipher. That's why all FoMoCo's have had claibration codes since 1986. Sorry, don't shoot the messenger. ------------------
Alex Denysenko
Co-Administrator and Moderator NHRA/IHRA/SRA member and licensed Superstock driver
MCA member# 53321
NHRA and IHRA SS/LA National Record Holder '00,'01,'02,&'03
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Professional Manwhore
The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
Quote #3: "If you can't run with the big dogs, stay on the porch!"
www.moneymakerracing.com
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SteveLaRiviere
Administrator Posts: 34763
From: Saco, Maine
Registered: May 99
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posted 01-06-2003 08:52 AM
quote:
Originally posted by cobravenom71:
So how is the car owner supposed to tell what engine is in his car? According to the engine tag it could be either a 351M or a 400, right? Seems to me there should be a definitive designation somewhere without having to check the VIN#.
The VIN code on mine is 'S', which denotes a 400 2-V. It also has a 2.47/1 rear gear,8.0/1 compression, 159 HP, and 315 lbs. of torque. With this combo in a 4800 lb. car, you can almost run faster than this car can drive. But hey, at least it still gets crappy gas mileage!
By the VIN. In the late 70s, early 80s, they even trained us to get the VIN code when asking for parts. Back then GM got into 'corporate' powerplants which meant your fancy Buick could have a Buick, Chevy, Pontiac, or Olds engine. {whatever plant wasn't striking at the time, I imagined} What was odd, was I could tell all the engines apart just by looking at them but the GM guys usually had to look up the VIN!  I used to laugh at them, and at night I used to yell at them "Hey! Are you sure that's your car you're getting into?"
------------------
'70 Mustang Mach 1 - '72 Mustang Sprint - '94 F-150 Remember our sponsors, Mustangs Plus, NPD, Osborn Reproductions, and MyFordPerformance.com.
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skips69
Gearhead Posts: 287
From: Catlin, IL USA
Registered: Mar 2001
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posted 01-08-2003 06:29 PM
quote:
Originally posted by clevelandstyle:
Where am I when deals like this are going down?
It sounds like it could be a Cleveland to me. Also, look on the front, top of the head, next to the valve covers and see if it has a 2 or a 4. Those would be Cleveland heads. If there is no number, it's a M head.
These heads have a 2 in the corners, and from some closer examination, this is definately a Cleveland engine. Got it running today with some fresh gas and battery - both rear tires spun, so it has trac-loc! My next question is; how did the guy get the factory 4V intake to bolt up to these 2V heads do you think? Unless it doesn't matter with the cast iron intake.....I know Edelbrock has two different part #'s for the Performer Intake - 1 is for 2V heads, the other for 4V heads. Just curious as I have always went the route of the Windsors myself.
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SteveLaRiviere
Administrator Posts: 34763
From: Saco, Maine
Registered: May 99
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posted 01-08-2003 06:35 PM
The 4V intake will bolt right up to the 2V heads. It's a heck of a mismatch, but they used to do it all the time when 351C parts were rare, one of the magazines even recommended it. {I think Hot Rod?}------------------
'70 Mustang Mach 1 - '72 Mustang Sprint - '94 F-150 Please remember our sponsors,
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