Still trying to determine my engine

Help Support 7173Mustangs.com:

Sheriff41

Well-known member
Joined
Aug 5, 2019
Messages
409
Reaction score
206
Location
Texas
My Car
72 Mustang Q-code
Yes, the H code block could have the same numbers, plus the date seems to match your car. The heads appear to be Q code 4V open chamber with a square bore intake manifold from an M code.

Getting the partial VIN from the back end of the block will tell you a lot. If it doesn't have a partial VIN that means it is a replacement block.

The symbol with the "F" in it means Cleveland foundry.
Don, did you notice the O4M date on the head? I'd venture the heads and intake both came off a '71 M-code. The 4-dot heads could be either closed or open chambered but the ones recorded in 351C.net's 4V Head Repository with similar date codes are D1AE GA closed chambers. Thoughts?
 
Joined
Jan 1, 2012
Messages
8,176
Reaction score
932
Location
Springfield, OR
My Car
1971 Mustang Sportroof M code
Don, did you notice the O4M date on the head? I'd venture the heads and intake both came off a '71 M-code. The 4-dot heads could be either closed or open chambered but the ones recorded in 351C.net's 4V Head Repository with similar date codes are D1AE GA closed chambers. Thoughts?
No, I didn't pick up on the date code. You are likely correct, both about being closed chamber and the casting number. I don't believe there were any open chamber 4Vs that early.
 
Joined
Jan 2, 2019
Messages
235
Reaction score
155
Location
Wisconsin
My Car
1972 Mustang convertible, 351C 2V with FMX (#'s matching)
Currently equipped with 351C 4V 4BM, .060 over, roller cam, Sanderson block huggers, -AC
Don, did you notice the O4M date on the head? I'd venture the heads and intake both came off a '71 M-code. The 4-dot heads could be either closed or open chambered but the ones recorded in 351C.net's 4V Head Repository with similar date codes are D1AE GA closed chambers. Thoughts?
I will add if I can as just like the block ID being a 4 BM or maybe a 2 and not knowing until you see ot.. there are #4 heads with the "big" dimple that are not closed chamber. When I bought my 4BM short block I saw the proof that is was a 4BM, but it was like Xmas morning when I pulled the heads and saw they were closed chambered. (The pic is before I repainted the valve covers in RB)
 

Attachments

  • EA5FE294-03D3-495B-9986-8101D8A8B276.jpeg
    EA5FE294-03D3-495B-9986-8101D8A8B276.jpeg
    701.7 KB · Views: 16
  • 4AE9CAD7-06D1-461E-ACE8-7D7B98C92864.jpeg
    4AE9CAD7-06D1-461E-ACE8-7D7B98C92864.jpeg
    851.2 KB · Views: 16
Joined
Jul 27, 2021
Messages
744
Reaction score
540
Location
East Texas
My Car
1971 Mustang Mach 1 M code 351 4 speed
The 4 on the cylinder heads means that those are certainly 4 barrel heads. I don't think you can figure out if they are closed or open chamber unless you look at the chambers themselves. Being that your car is an H code car, at least the heads have been changed. Did you modify the heads for the screw in studs and guide plates? To know if that is your original block, you will need to look under the drivers side head, on the block for the vin number and see if it matches your vin.
 

Hemikiller

Well-known member
Staff member
Moderator
Joined
Jul 12, 2010
Messages
3,666
Reaction score
934
Location
Killingworth, CT
My Car
71 Mach 1
65 coupe
D2AE-CA was used on the 71 351CJ engine, and *all* 72-74 351C regardless of 2 bolt or 4 bolt mains. That includes H code 2V, Q code 4V and the '72 only 351HO. Way too many websites out there with BS information. The only difference is whether or not it's 2 or 4 bolt, and it's pretty much irrelevant other than for bragging rights.

0M4 (Dec 4 1970) with the 4* will, with 99.9% certainty, be D1AE-GA closed chamber heads. At that time, the 351CJ with it's open chamber 4V heads wasn't released yet, that was to happen in May '71.

1A29 on the intake (Jan 29 1971) is probably not the original intake for the heads, the date spread is too wide. If it has a four barrel carb bolted to it, then it's a 4V intake, as Ford didn't make a 4 barrel pad on a 2V intake.

So, you have a '72 351C block with a '71 M-code top end. The Crane stud conversion kit is a bonus.
 
Joined
Sep 12, 2015
Messages
5,908
Reaction score
974
Location
SW Ontario
My Car
1971 Mustang Mach 1, M code, 4 speed.
No, I didn't pick up on the date code. You are likely correct, both about being closed chamber and the casting number. I don't believe there were any open chamber 4Vs that early.
I would also have to think that open chamber heads would be a later date code, well into 71. 0M4 is 1970 Dec 4th which are very close to mine and they are closed chamber. If I'm right, open chamber heads didn't appear until around April or May of 71 for the 72 year Q code cars.
 
Joined
Jan 2, 2019
Messages
235
Reaction score
155
Location
Wisconsin
My Car
1972 Mustang convertible, 351C 2V with FMX (#'s matching)
Currently equipped with 351C 4V 4BM, .060 over, roller cam, Sanderson block huggers, -AC
D2AE-CA was used on the 71 351CJ engine, and *all* 72-74 351C regardless of 2 bolt or 4 bolt mains. That includes H code 2V, Q code 4V and the '72 only 351HO. Way too many websites out there with BS information. The only difference is whether or not it's 2 or 4 bolt, and it's pretty much irrelevant other than for bragging rights.

0M4 (Dec 4 1970) with the 4* will, with 99.9% certainty, be D1AE-GA closed chamber heads. At that time, the 351CJ with it's open chamber 4V heads wasn't released yet, that was to happen in May '71.

1A29 on the intake (Jan 29 1971) is probably not the original intake for the heads, the date spread is too wide. If it has a four barrel carb bolted to it, then it's a 4V intake, as Ford didn't make a 4 barrel pad on a 2V intake.

So, you have a '72 351C block with a '71 M-code top end. The Crane stud conversion kit is a bonus.
Hemi,
I have a few more mystery questions... on jscott's photo his dot looks smaller than the ones on my quench heads. Also, is there any meaning to the dots on the #4&5 exhaust ports?
 

Attachments

  • 19C9CF6C-AA74-4A0A-B15B-3997BFB2AC15.jpeg
    19C9CF6C-AA74-4A0A-B15B-3997BFB2AC15.jpeg
    2 MB · Views: 24
  • E5F5C1FD-F4BC-4055-98A4-ECECE8798988.jpeg
    E5F5C1FD-F4BC-4055-98A4-ECECE8798988.jpeg
    2.1 MB · Views: 24
Joined
Aug 30, 2014
Messages
1,447
Reaction score
126
Location
Delaware
My Car
Stock 1973 Mustang Convertible with a 351C 2v and C6
Modified 1970 Mach 1 M-Code with a 351C 4v Manual

Just below the driver's side cylinder head on the rear of the block. Use a mirror if the engine is still in the car.

The date code on your cylinder head (OM4) is Dec 4th, 1970 so you may have closed chamber heads.
I have a set of 1970 DOAE-L 4v heads on my 1970 Mach with a casting date of 9M16. I can confirm that DOAE-L 4v with a casting of OMxx were closed chamber heads with 61-64cc chambers. D1ZEs (with the exception of the 351 BOSS D1ZE-B) heads were open chamber. The D1ZE-DA and D3ZE were 1971 and 1973 CJ respectively, and D2ZE-A were 1972 H.O. and all were open 73-76cc chamber.

The D2AE-CA block was used on 2vs and 4vs in 1972 and 1973, and in 1974 on other Fords (Torino, etc). Many were 2 bolt mains. I have 3 D2AE-CAs and all are H-code motors cast in 1973 with 2 bolt main. The only way to know for sure if yours is a 2 or 4 bolt is to drop the oil pan.

JScott: I suspect your 72 H-code had its 2v Open Chamber Heads swapped for a set of '70 closed chambers at some point in its past. Does it have a stock 4v intake and exhaust too? As Sheriff4 said the VIN or partial VIN on the machined section behind the driver's side head, and is hard to read with the engine installed.. You can find the assembly date on the left side machine face area behind the water pump (second picture)
 

Attachments

  • VIN on Rebuilt block in copper car.jpg
    VIN on Rebuilt block in copper car.jpg
    238.6 KB · Views: 14
  • 20190619_161056.jpg
    20190619_161056.jpg
    4.4 MB · Views: 14
Last edited:

Hemikiller

Well-known member
Staff member
Moderator
Joined
Jul 12, 2010
Messages
3,666
Reaction score
934
Location
Killingworth, CT
My Car
71 Mach 1
65 coupe
Hemi,
I have a few more mystery questions... on jscott's photo his dot looks smaller than the ones on my quench heads. Also, is there any meaning to the dots on the #4&5 exhaust ports?

Not sure what those are for. I would "assume" the numbers next to the dots are mold numbers for QC purposes. I have a set of 72 351CJ heads, will have to compare dot sizes with the 71 M-code heads I have.
 
Joined
Jan 1, 2012
Messages
8,176
Reaction score
932
Location
Springfield, OR
My Car
1971 Mustang Sportroof M code
Not sure what those are for. I would "assume" the numbers next to the dots are mold numbers for QC purposes. I have a set of 72 351CJ heads, will have to compare dot sizes with the 71 M-code heads I have.
Good idea, I also have a set of each, and will compare mine too, see if there is any consistency.
 
Joined
Sep 3, 2015
Messages
638
Reaction score
51
Location
AZ
My Car
1972 Mach 1
1971 Ranchero
Hemi,
I have a few more mystery questions... on jscott's photo his dot looks smaller than the ones on my quench heads. Also, is there any meaning to the dots on the #4&5 exhaust ports?
I've noticed at least 2 different "dots" on 4v heads and haven't been able to correlate to anything, thus far.
 
Joined
Sep 12, 2015
Messages
5,908
Reaction score
974
Location
SW Ontario
My Car
1971 Mustang Mach 1, M code, 4 speed.
IMO, the "dot" size is strictly due to the casting patterns used during the casting process. I'm bloody sure there were several 'patterns', as they are called, used and therefore variations between them, slight as they might be. The dot may have been a simple bump in the pattern surface. These heads and blocks are all 'sand cast' and no two will ever be exact. Patterns back in the 60's-70's were basically hand made, not like the CNC processes we are now accustomed to.
I too, had a set of 70 N heads and they only had a "4" on them, no dot. Why the dot was added for the 71 series, no idea, but at a guess as a quick ID between slightly higher compression 70 N heads and the so called 10.7:1 GA heads for early 71.
 
Last edited:
Joined
Jan 2, 2019
Messages
235
Reaction score
155
Location
Wisconsin
My Car
1972 Mustang convertible, 351C 2V with FMX (#'s matching)
Currently equipped with 351C 4V 4BM, .060 over, roller cam, Sanderson block huggers, -AC
Not sure what those are for. I would "assume" the numbers next to the dots are mold numbers for QC purposes. I have a set of 72 351CJ heads, will have to compare dot sizes with the 71 M-code heads I have.
I maybe understand having the 4 and 5 numbers cast into the ports to more easily have the sorters and assemblers have a quicker ID to grab the head on their side of the engine because it's not like they would fit too well if you put them on backwards. 🤷🏻‍♂️
 
Joined
Jul 27, 2021
Messages
744
Reaction score
540
Location
East Texas
My Car
1971 Mustang Mach 1 M code 351 4 speed
At one time I did some research on the 4 with dot or no dot heads. Some people say that if they have or do not have the dot that will correlate to if they are closed chamber or open chamber heads, but I saw photos of both 4 dot heads and 4 no dot heads that were both closed chamber. From what I was able to tell, that dot does not really mean anything, at least nothing that anyone has been able to figure out yet. Maybe there were multiple molds for making the exact same 4 V heads and they would differentiate which mold the head came from by that dot.
 
Joined
Jan 2, 2019
Messages
235
Reaction score
155
Location
Wisconsin
My Car
1972 Mustang convertible, 351C 2V with FMX (#'s matching)
Currently equipped with 351C 4V 4BM, .060 over, roller cam, Sanderson block huggers, -AC
The heads are not left or right, and can be used on either side.
The bare heads looked the same to me except with the 4th cyl / 5th casted into them to say which bank to go to. When my heads came back from machine shop, they pencil painted L and R on them which I thought was odd because the exhaust ports already let you know where they belonged in the block.
 
Joined
Sep 12, 2015
Messages
5,908
Reaction score
974
Location
SW Ontario
My Car
1971 Mustang Mach 1, M code, 4 speed.
At one time I did some research on the 4 with dot or no dot heads. Some people say that if they have or do not have the dot that will correlate to if they are closed chamber or open chamber heads, but I saw photos of both 4 dot heads and 4 no dot heads that were both closed chamber. From what I was able to tell, that dot does not really mean anything, at least nothing that anyone has been able to figure out yet. Maybe there were multiple molds for making the exact same 4 V heads and they would differentiate which mold the head came from by that dot.
Did you read post #34? That's my thoughts on the subject.
 

Sheriff41

Well-known member
Joined
Aug 5, 2019
Messages
409
Reaction score
206
Location
Texas
My Car
72 Mustang Q-code
At one time I did some research on the 4 with dot or no dot heads. Some people say that if they have or do not have the dot that will correlate to if they are closed chamber or open chamber heads, but I saw photos of both 4 dot heads and 4 no dot heads that were both closed chamber. From what I was able to tell, that dot does not really mean anything, at least nothing that anyone has been able to figure out yet. Maybe there were multiple molds for making the exact same 4 V heads and they would differentiate which mold the head came from by that dot.
351c.net has some threads on this topic. There is a registry one of the members put together on the no dot/dot and it seems to be a running change. Also captured was some CC/OC data. Bottom line: if you have a 4-dot you may have to dig deeper to know if you have CC or OC heads.
 
Top