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M Code, H Code visual difference
#1
If I were looking at a 71 mustang that did not have matching numbers and the seller states that it's a M code, is there a way that I could visually confirm that fact? How could I tell the difference between 351 engines such as an H code vs M code?

Or for that matter, how could I tell the difference between a 351 and a 302?
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#2
The simplest way is to look at the 5th character in the VIN. If it's an "M" then you have an M-code.

The engine block is the same for M and H codes. The cam, heads, intake and exhaust manifolds, carb, air cleaner, and other things were different.

[Image: 386_07_10_13_5_58_42.jpeg]
My Mustangs:
71 M-code Mach 1, Medium Blue/White Sport, 4R70W, 3L50, Factory Ram Air.
72 Q-code Mach 1, Pewter/Black Sport, 4-spd, 3L25.
65 Convertible, Britney Blue/White/White, more modified than original.
05 Convertible, Legend Lime/Tan/Tan, future classic??
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#3
Don65Stang;183636 Wrote:The simplest way is to look at the 5th character in the VIN. If it's an "M" then you have an M-code.

The engine block is the same for M and H codes. The cam, heads, intake and exhaust manifolds, carb, air cleaner, and other things were different.

Don, thanks for the quick reply. I've recently learned about decoding Vin numbers, but what I want to understand now is - How can I varify that the engine in the vehicle is what the Vin number says it should be or what the seller is claiming it is?

It sounds like I need to become familiar with cams, heads and manifolds. Is that correct?
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#4
There is no easy way to tell for certain. However all M, Q and R code heads have a raised "4" or "4*" that is easily seen at the top left corner of the head where the valve cover bolts down. If it has a 4 then it is a 4v head which means it has a 4 barrel intake and carb which would have come on an M-code.
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#5
Can you tell by looking at the inlet manifold or exhaust manifold?

[Image: Image3.png]
Jim
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#6
Did he provide a photo of the car from the rear? If single exhaust, H-code. If dual, M-code or one of the few '71 Q-codes.

Can he simply provide you the VIN? Fifth digit will be the engine code.

-Kurt

[Image: satellite-valiant-mustang-license-tags-signature.png]
How to buy a '71-73 Mustang:
Rule #1: Assume all classic car sellers are guilty until proven innocent.
Rule #2: No classic car dealer is ever innocent; thus, they are all guilty.
Rule #3: Buy from trustworthy people: Fellow forum members. Visit 7173Mustang's For Sale forum.
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#7
I can't work out whether he's trying to work out if the engine itself is still an mcode or whether the car was born an mcode....

[Image: Image3.png]
Jim
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#8
JimNiki;183656 Wrote:Can you tell by looking at the inlet manifold or exhaust manifold?

Yes. Exhaust manifolds look different between 2v and 4v, as well as intakes. Real obvious if they are factory iron.

1973 Mach 1 Q code 351 4V, 9A paint, standard interior, 3.50 rear, C6 trans.
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#9
I would agree that there is no easy way to ID differences with out some bit of effort. Check out this web site. It could offer some help.
http://www.mustangtek.com/index.html
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#10
As mentioned...

The 4 barrel heads have a number 4 on the top corners of each head. See the pic below. If the heads are there then likely that your exhaust manifolds, intake manifold and carb are all 4 barrel which is what an M code car is.

[Image: 9tn0ax.jpg]

Jeff
1972 Q Code Convertible
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