Topic: V8 Distributor Advance Units Collected

[krelboyne]

Sorted through a bunch of Autolite and Motorcraft distributors. Ford called them a Diaphragm Assembly - 12370.
Sharing what I found. Lets start with the dual advance units. Banded style.

My finding show that it (they) were used starting in 1968. Ford part numbers in some of the casting are: C8AF-12378-C and C8AF-12378-D. This would be for the 2 piece banded style advances. I think that these were used 1968-71? I found 3 distinct versions, two with part numbers, and without.
The C8AF-12378-C versions have 2 different fonts for the Ford numbers. The -C version has a threaded brass nipple on the outer, pressed in brass nipple on the inner port.
The C8AF-12378-D versions have 2 different fonts for the Ford numbers. The -D version has both brass nipples pressed into the housing.

The third version of banded dual units has no Ford number, but has "AUTOLITE" stamped into the side of the threaded housing. The nipple is part of the casting. My version has a "B12" mark.
Pictures show banded style dual advance units, there may be more?

[kitdoctor]

This topic has interested me for some time.

Let's say there are two units side by side that are visually identical e.g. same nipple style, same font style for marking, same stamped code e.g. A12, B12 etc. Is it only the removable internal pieces (i.e. washers, spacer and spring) that vary between say a unit for a six cylinder application versus an eight cylinder application?

Also, what does the stamping A12, B12, HP6 etc. signify?

Finally, when these unit pop up on ebay there are never any of the internal pieces. Were they originally sold like that and the old pieces were reused, new internal pieces bought separately or have the new pieces become separated?

[J_Speegle]

This topic has interested me for some time.

Let's say there are two units side by side that are visually identical e.g. same nipple style, same font style for marking, same stamped code e.g. A12, B12 etc. Is it only the removable internal pieces (i.e. washers, spacer and spring) that vary between say a unit for a six cylinder application versus an eight cylinder application?

No for these two applications they are shaped differently. For lack of a better description (looking straight down from the top) the V8 one attaches from approx 3-6 o'clock while the 6 cylinder attaches from 6 to 9 o'clock

I'll just post a picture

Both 68's (sorry was a bit warm to go out and get a NOS 6 cylinder out and take a picture) Upper left big bloc - lower right a 6 cylinder





Now back to the discussion leaving the 6 cylinders out

Also, what does the stamping A12, B12, HP6 etc. signify?

Those were identifier codes I believe.

[kitdoctor]

Ah now I see the difference between the units for eight cylinder versus six cylinder applications.

In relation to the identifiers (e.g. A12) I see examples of units for a six cylinder application and an eight cylinder application with the same identifier (A12 is a good example) appearing on both. So, I wonder what they identified?

[J_Speegle]

In relation to the identifiers (e.g. A12) I see examples of units for a six cylinder application and an eight cylinder application with the same identifier (A12 is a good example) appearing on both. So, I wonder what they identified?

Where are you finding these two references? MPC,, Ready Reference or elsewhere?

The CJ site has some reference for the advances and the stamping for some of their covered years and option combinations.

https://www.428cobrajet.org/id-dist-vac-advance

Since the outside castings are shared the different must be the calibration through different springs and washers. Those are listed in the MPC from what I saw. There are other differences. at least one exterior one that you can see as well as internally .

Here are a few I had in my files from for some  68 - 70 applications