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72 351c in my 70 mach 1

M

miketyler

Member
Engine has been out on the stand for several months. Was cleaning and prepping this past weekend and realized that part number D2xx is cast on the bottom side. So this is a 72 block? Is the 72 351c a lesser HP engine than the 70 that came with the car?

Also, the crank pulley has a later part number, I believe begins with D4 and is 4groove with a very small V-groove at the aft most position. Was going to start shopping for billet pulleys but wanted to be sure I get right diameters for this engine running AC. I dont want to use underdrive pulleys and sacrifice any water pump rpm's.

With the newer block, what should I consider when purchasing parts? Or are they basically the saame?
 
As I understand it, starting in '71 ALL 351C 4V blocks switched to 4 bolt main caps. While this would have no effect on installation into the car, it should be a "stronger" motor. Performance differences between '70 and '72 should be minimal, if any.

Understand also Ford's coding system.... the D2XX block code does not mean the engine came out of a 1972 car, it means that block standard was first introduced in 1972... if the standard remained unchanged for a number of years it could have been used in any '72 and later vehicle until the standard changed again. With a D4XX crank pulley, it's likely a 1974 engine.

This is why you'll see C5ZZ parts on '66 and up Mustangs... it's because the design of the part didn't change though the model years.
 
Mike, there should be a date code near the same location where you found the D2 numbers on the block. Let us know the date code and this will better help determine the year of the block. Honestly, other than the 4 bolt difference there isn't a whole lot that changed with the blocks AFAIK. The big thing is to figure out of you have the open/closed 2V or 4V heads.
 
Block is two bolt mains, and sure looks like 4V heads. I will get block date code. What is identifying characteristics of 4V heads?
 
The heads will have a 2 or a 4 cast into them. Should be in plain sight near the lip of the valve covers.
 
What is identifying characteristics of 4V heads?
Click to expand...

Upper front (or rear) top corner of the cylinder head will have a raised "4" if they are 4V heads, if they're 2V heads, I believe there is nothing there... i.e., NOT a "2".

If the exhuast manifolds are removed, you should be able to go to your nearest Subway restaurant and order any sub sandwich from the menu. Bring the sandwich home to your engine and if the end of the sandwich fits into the exhaust ports it's a 4V head.

What I'm getting at is the exhaust ports on 4V heads are HUGE... thus supporting the "deep breathing/high revving" characteristics of the 351C-4V.
 
My 71 had a 2 cast in both heads. It was an H code.
2v_or_4v.jpg
 
Yes, the intake and exhaust ports on the heads are huge and they do have the "4" cast into the upper corner.

Here is casting on bottom side of block.
 
The 3L1 denotes it was made in 73, no? I found these codes from a 351C site

Year Type Casting Part
================================================== ============================
1970 2-Bolt D0AE-A,D0AE-C,D0AE-E,D0AE-G,D0AE-J,D0AE-L D0AZ-D
1971 2-Bolt D0AE-A,D0AE-C,D0AE-E,D0AE-G,D0AE-J,D0AE-L D0AZ-D
1971 2-Bolt (CJ) D2AE-CA D1ZZ-A
1971 4-Bolt (HO) D0AE-B,D0AE-D,D0AE-F,D0AE-H ????-?
1971 4-Bolt (CJ) D2AE-CA D3ZZ-A
1971 4-Bolt (BOSS) D1ZE-A,D1ZE-B D1ZZ-D
1972 2-Bolt D2AE-DA DOAZ-D
1972 2-Bolt (CJ) D2AE-CA D1ZZ-A
1972 4-Bolt (HO) D2AE-EA D1ZZ-D
1972 4-Bolt (CJ) D2AE-CA D3ZZ-A
1973 2-Bolt D2AE-DA DOAZ-D
1973 2-Bolt (CJ) D2AE-CA D1ZZ-A
1974 4-Bolt (CJ) D2AE-CA D3ZZ-A
1974 2-Bolt D2AE-DA DOAZ-D
1974 2-Bolt (CJ) D2AE-CA D1ZZ-A
1974 4-Bolt (CJ) D2AE-CA D3ZZ-A

HO = High Output
CJ = Cobra Jet
BOSS = Boss 351"
 
Yep, the first digit of the date code is year, then month (no letter "I"), then day. So your block was made on Nov 1, 1973 and would have came in a 1974 car.
 
ok, that makes sense now although the Cobra Jet proposition did seem interesting. The harmonic balance I took off of it is D4XX and has a huge counterwight cast into its back side. I wanted to be sure that it was correct but I suppose should be matched to the crank, not the block, eh?
 
am considering March high flow pulleys. I called them and their recommended kit for PS and AC cars is their #1685. This kit is 3-groove crank and is 5.75 dia but my pulley that came on the car is around 8.4". Should I be concerned or? I guess as long as the WP and crank ratio is at least as it was on the AC car originally, I should be ok?

Also that pulley has 4 groooves, any idea what that smalles groove closes to the balanacer was used for? Crank pulley is D3AE-6512-CA
 
Most likely a smog/thermactor pump.

I'm surprised their pulley is that much smaller. They know what they are doing though
 
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