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In general, a 4 in the corner of the head without a dot is a sure sign you have a quench chamber head; most likely a D0AE casting with 63cc chambers although the first month (June) of D1AE castings omitted the dot as well. Heads having a 4 with a dot in the corner are not as easy to identify.

The casting numbers are cast into the bottom of an intake port runner, to view the casting number requires removal of the intake manifold and viewing the bottom of the intake ports with a mirror and flashlight.

In lieu of pulling the intake manifold, you can remove a valve cover and read the casting date which is cast into that area of the head. The casting date is a 3 or 4 digit number composed of a number indicating the year, a letter indicating the month, and one or two more numbers indicating the day of the month. January 11, 1971 = 1A11

4 no dot - D0AE casting - 63cc quench - 7/69 thru 5/70 - 9Gxx thru 0Exx

4 no dot - D1AE casting - 66cc quench - 6/70 ............. - 0Fxx

4 + .dot - D1AE casting - 66cc quench - 7/70 thru 1/71 - 0Gxx thru 1Axx

4 + .dot - D1ZE casting - 75cc open.. - 4/71 thru 4/72 - 1Dxx thru 2Dxx

4 + .dot - D3ZE casting - 78cc open.. - no data

The casting date data is based on a survey performed at the Cleveland's Forever Forum, the data was rather incomplete in regards to D1ZE and D3ZE castings. Although its not reflected in the survey data, I listed the earliest D1ZE castings as being cast in April 1971 (1Dxx) because 1971 Cobra Jet motors were installed in Mustangs, Torinos, etc beginning May 1971.

The D1ZE castings have 75cc open combustion chambers and 2.19"/1.71" valves. D3ZE castings were installed in the motors equipped with exhaust gas recirculation, these should be the OEM heads installed on the motors of all Pantera L models. These heads have 78cc open combustion chambers and 2.04"/1.65" valves. although the valves were smaller the ports were the same size as the ports found in all other 4V head castings.

There were D1AE-GA castings having 66cc quench chambers cast in 1974 and 1976 (4xxx or 6xxx date codes) in order to provide a supply of quench chamber heads for racing.

-G
Last edited by George P
quote:
Originally posted by captaintobeys:
What are the casting numbers for the Boss Engine with the 11.1 CR and specs if you know them.


The 1971 R code motor (aka Boss 351 or 351 H.O.) used D1AE heads (66cc chambers) and pistons with small pop-up domes. Although advertised as having 11:1 compression its true compression ratio was about 10:1.

The 1971 M code motor (aka 351C 4V) used the same heads and flat top pistons. It was advertised as having 10.7:1 compression, the true compression was 9.7:1 at best.

The 1970 & 1971 351C 4V & Boss engines were all advertised as having about 1 whole number more compression than they really had. I'm sure the 4V Clevelands were originally intended to have 11:1 compression, but by the time the Cleveland went into production the compression ratios had been reduced; adjusted no doubt because of the impending changes in gasoline octane.

In the late 1960s the highest octane pump gas had octane in the mid to high 90s, but when they "took the lead out" the highest octane gasoline you could buy here in So Cal was 91 octane low lead or 92 octane unleaded.

I've never seen an explanation why Ford continued to quote the inflated compression ratio numbers instead of choosing to be truthful. The 8.6:1 compression ratio quoted for the Q code (351 Cobra Jet) motors was honest however.

The earliest 351C block castings (D0AE-J castings) had slightly thicker cylinder walls because they were intended to have 11:1 compression, when the compression ratio was dropped the cylinder walls were cast thinner in order save a little bit of money on the castings.

-G
Last edited by George P
quote:
No stamp on the outside that will show if it is a closed or open chamber. As best I remember, you get the joy of taking the head off the block to find that out.


If you know what to look for, often one of the flexible cameras can determine your head shape and piston surface w/o removing the head. Has saved me trouble recently...
quote:
Originally posted by George P:
quote:
Originally posted by captaintobeys:
What are the casting numbers for the Boss Engine with the 11.1 CR and specs if you know them.


The 1971 R code motor (aka Boss 351 or 351 H.O.) used D1AE heads (66cc chambers) and pistons with small pop-up domes. Although advertised as having 11:1 compression its true compression ratio was about 10:1.

The 1971 M code motor (aka 351C 4V) used the same heads and flat top pistons. It was advertised as having 10.7:1 compression, the true compression was 9.7:1 at best.

The 1970 & 1971 351C 4V & Boss engines were all advertised as having about 1 whole number more compression than they really had. I'm sure the 4V Clevelands were originally intended to have 11:1 compression, but by the time the Cleveland went into production the compression ratios had been reduced; adjusted no doubt because of the impending changes in gasoline octane.

In the late 1960s the highest octane pump gas had octane in the mid to high 90s, but when they "took the lead out" the highest octane gasoline you could buy here in So Cal was 91 octane low lead or 92 octane unleaded.

I've never seen an explanation why Ford continued to quote the inflated compression ratio numbers instead of choosing to be truthful. The 8.6:1 compression ratio quoted for the Q code (351 Cobra Jet) motors was honest however.

The earliest 351C block castings (D0AE-J castings) had slightly thicker cylinder walls because they were intended to have 11:1 compression, when the compression ratio was dropped the cylinder walls were cast thinner in order save a little bit of money on the castings.

-G


Years ago I bought a pair of service Boss heads with those casting numbers.

When I went to my A3 heads iron heads were no longer of any use so I sold them.

The guy I sold them to demanded his money back and claimed fraud on my part. He claimed real Boss heads had a D1ZX casting number on the runner?
I'm just repeating what I was told.

I was told at the time when I bought them that the service Boss heads had a different casting number than the production heads.

I was told that Ford took the hydraulic lifter head version and had them machined for the Boss solid lifter valve train.

I can't confirm either story. I didn't make the things.That source is generally very reliable.

I think the original 4 bolt block was different that the service block as werll?

The original was a 4 bolt version of the D0AE block and the service part for it is the D2AE-CA block.

The D1ZZ balancer also was never serviced. It was replaced by the D2ZZ balancer.

The original '71 Boss engineering numbers were only available in the assembly line version.

Distributor also.

Might have been a D1ZZ casting number on the heads rather than a ZX?

I'm not going to go calling anyone wrong and go argue with an entire web site, but let me put it to you this way, show me a bunch of pictures of heads off of real Boss 351 production cars and I will accept that casting number.

It was an issue that cost me some money and a lot of grief a long time ago. It is fairly etched in memory even 40 years later. Big Grin
quote:
Originally posted by PanteraDoug:


When I went to my A3 heads iron heads were no longer of any use so I sold them.

The guy I sold them to demanded his money back and claimed fraud on my part. He claimed real Boss heads had a D1ZX casting number on the runner?


I think that guy was mistaken.

There was a intake manifold with D1ZX cast on a runner, don't know about a head.

I think he owes you a apology.

He sounds like a part numbers Nazi.
quote:
Originally posted by Aus Ford:
quote:
Originally posted by PanteraDoug:


When I went to my A3 heads iron heads were no longer of any use so I sold them.

The guy I sold them to demanded his money back and claimed fraud on my part. He claimed real Boss heads had a D1ZX casting number on the runner?


I think that guy was mistaken.

There was a intake manifold with D1ZX cast on a runner, don't know about a head.

I think he owes you a apology.

He sounds like a part numbers Nazi.


I think that the original Ford part number was D1ZZ, not the casting number?

Alot of guys like that got shot in the back by their own troops in Viet Nam. They just went down as MIA. Wink
can anyone help with identifying this 351C head? I've searched and searched but can't figure out what i actually have.

First, it there is a 4Dot stamped on the head.
Second, (picture attached) it looks like the stamp on the head is OK38...obviously it's not the whole stamp but i can't find anything that even starts with those letters/numbers

anyone??

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  • 9121022066_IMG_2921_JPG
Last edited by George P
Lots of 4V heads have been machined for studs (adjustable valve train) over the years. The Boss heads were also machined for spring cups, not as many people duplicate that so if the head is machined for spring cups there's a better chance it may have originally been a Boss 351 head.

Below is a picture of a Boss 351 head, unused, still in the box. Notice the springs pads around the valve guides are machined flat.

Attachments

Images (1)
  • boss_351_head
pretty sure my first set of quench heads were D1ZX, high school classmate sold them to me then later down the road (after his dad found out they were gone) asked if there was any chance he could get them back

they must've been pedestal when i got them because that's the only set i would've had machined for studs, so mine were not originally R code

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