Topic: 70 Ported Vacuum Switches (PVS) Distributor Vacuum Control

[J_Speegle]

Was doing some research helping out a need on another site and came up with a little info I thought I should post/share here for members

The ported vacuum switch PVS was attached to the engine at the thermostat housing on most V8 engines used in 1970 Mustangs and controlled the vacuum to the vacuum advance housing attached to the distributor

The C8AE-A version that had been used through 69 production apparently continued to be used and made up into fall of 1969. Latest C8AE-A version I've got records of is from August 1969

D0AE-A version with the Pat. Pend markings were introduced into production in late 1969 (earliest date I've found on one has been October 1969) A later version with a larger sensor/bulb, lack of the Pat Pend lettering and a reinforced upper nipple can often be found also. Since there are no dates on these I've got no evidence of when they started to be used on a production engines in Mustangs.   The latest date I've found on a Pat Pend D0AE-A version has been April 71

NOTE: In the date code stamping a letter was placed between the month and year (as shown in the dating parts article in the library) The letter is believed to indicate the supplier/maker of the part.

Sorry some of the pictures below show the valves/switches in their unrestored condition. The are examples for only markings, design characteristics and other features in this discussion

C8AE-A compared to the D0AE-A Par Pend version





Comparing D0AE-A Pat Pend version verses the later D0AE-A switches/valves. Differences - date or lack of date - upper body marking - large verses smaller bulb/sensor





Reinforcement added to the later D0AE-A non-dated version



 

[specialed]

The 3 nipples are shorter on the doae than the c8ae version & both types of doae was used starting in 70 & I think the 2 doae versions was a vendor change. What I have found on the 2 doae types used depended on the size of the engine & which engine plant assembled the engine & when it was assembled depending on the vendor type used.  These vacuum trees usually don't get changed & if you study certain ford size engines from 68 -74 you can doc the changeover. In 75 ford made a d5ae version also.

[J_Speegle]

The 3 nipples are shorter on the doae than the c8ae version & both types of doae was used starting in 70 & I think the 2 doae versions was a vendor change. What I have found on the 2 doae types used depended on the size of the engine & which engine plant assembled the engine & when it was assembled depending on the vendor type used.  These vacuum trees usually don't get changed & if you study certain ford size engines from 68 -74 you can doc the changeover. In 75 ford made a d5ae version also.

Thanks Ed for your input and sharing your experiences.

Have you paid attention (I haven't) to which ones came on the more common (for restoration) 70 cars?  Boss 302- Boss 429 and the CJ

Will check my pictures to see if I can find any clue - difficult given the pictures and the small size of the details we're looking for

Its possible that with the change from the 68  in which we've documented two suppliers (one marked the switches with a "K" and one with an "H" - likely Holley) when they changed to the new design the "H" versions kept the date code pattern (since they continue to be marked with the "H" and the supplier identified by the "K" dropped the date as a way to track batches or issues.

Again thanks for the sharing   

[sah62]

Its possible that with the change from the 68  in which we've documented two suppliers (one marked the switches with a "K" and one with an "H" - likely Holley) when they changed to the new design the "H" versions kept the date code pattern (since they continue to be marked with the "H" and the supplier identified by the "K" dropped the date as a way to track batches or issues.

For what it's worth I'm still trying to dig up any documentation at all to confirm our suspicion that the "H" and "K" were used to identify suppliers. I had thought that "K" might stand for Kelsey-Hayes, but I haven't found anything at all to suggest that K-H made emissions parts. Does anyone know any other Ford suppliers whose name starts with a "K"?

[Bob Gaines]

For what it's worth I'm still trying to dig up any documentation at all to confirm our suspicion that the "H" and "K" were used to identify suppliers. I had thought that "K" might stand for Kelsey-Hayes, but I haven't found anything at all to suggest that K-H made emissions parts. Does anyone know any other Ford suppliers whose name starts with a "K"?

Kem MFG CO is one, Kysor is another.

[sah62]

Kem MFG CO is one, Kysor is another.

Hmm, KEM does make emissions parts: http://www.bloomberg.com/research/stocks/private/snapshot.asp?privcapId=6512201

[Anghelrestorations]

Great discussion here.  I will add a few comments.

Understand that there is a focus on 1970 for these PVS, but these were actually used starting in late 1967.  I have date codes of the C8 version that show that so would seem for the 1968 model year they started using this.

The changeover date from the C8 to the D0 version seems to probably be about September 1969 as I have both versions with those date codes.

One of the original manufacturers most likely was Dole (see below).  They were making various control valves and thermostats at the time so maybe the other vendor was also manufacturing thermostats.  Could be a possibility since they are complimentary products.

The pictures I have here is of an original NOS unit I bought to see both the finish and to show who the manufacturer was at the time.  Its identical to the Ford switches we are talking about, stamped in 1970, and marked the same way.   







 

[Bob Gaines]

Great discussion here.  I will add a few comments.

Understand that there is a focus on 1970 for these PVS, but these were actually used starting in late 1967.  I have date codes of the C8 version that show that so would seem for the 1968 model year they started using this.

The changeover date from the C8 to the D0 version seems to probably be about September 1969 as I have both versions with those date codes.

One of the original manufacturers most likely was Dole (see below).  They were making various control valves and thermostats at the time so maybe the other vendor was also manufacturing thermostats.  Could be a possibility since they are complimentary products.

The pictures I have here is of an original NOS unit I bought to see both the finish and to show who the manufacturer was at the time.  Its identical to the Ford switches we are talking about, stamped in 1970, and marked the same way.   







 

I have never seen any marked with a "D" . Maybe others have.

[Anghelrestorations]

I also have never seen one marked with a D and doubt you will ever see that.  If you look at the pictures I posted the valve is marked with an H that matches what we see on the valves we are talking about here.

Something else to consider..... is that the K and the H marking has nothing to do with a manufacturer identification at all.  Could be there is an internal mechanical difference between the two.  Perhaps this matches with the temp rating of the thermostat or some internal difference in the valve we dont know about.  Thats another possibility.   

[J_Speegle]

I also have never seen one marked with a D and doubt you will ever see that.  If you look at the pictures I posted the valve is marked with an H that matches what we see on the valves we are talking about here.

Could Dole have purchased and reboxed  switches made by another provider?

Interesting - have never seen or found one marked on the body like your example - also interesting that the Dole design (besides the DOLE rather than the D0.....) also still has the Pat Pend on the upper section  but its reversed. Seems odd to have them designed both ways

Something else to consider..... is that the K and the H marking has nothing to do with a manufacturer identification at all.  Could be there is an internal mechanical difference between the two.  Perhaps this matches with the temp rating of the thermostat or some internal difference in the valve we dont know about.  Thats another possibility.

Don't see any reference to that in Ford or other books on emissions that cover these switches nor anything in the replacement catalogs that suggest that selection should be made based on some temp/mechanical difference. Same thing with the two different D0 versions

[Anghelrestorations]

Dole is definitely the manufacturer since they are the ones who applied for the patent and have the patent on this.  They are mentioned as Dole Valve Company in the patent.  So if you follow that line of thinking it would be hard to think that there is a second manufacturer making the same part in cooperation with Dole at that time.  You would figure Dole would want the sole rights to this switch and manufacture themselves.  Something else to think about. 

I looked in the Ford MPC as well and I see that its one single part number that covers a variety of applications - so nothing in the Ford books to show a difference. 

Hopefully we will figure it out at some point and decipher exactly what the K and the H really mean.   

[krelboyne]

There may have been two different (Dole?) plants, or manufacturing facilities represented by the "K" and "H".
My MPC's list only one part number of C8AZ-12A091-A, for the type 2, distributor vacuum control valve assembly. It also lists "(DY-126)".

[Anghelrestorations]

Thats what I saw Scott.  Two different plants is another good idea.  Thats a possibility. 

[J_Speegle]

There may have been two different (Dole?) plants, or manufacturing facilities represented by the "K" and "H"....

A possibility - Gabriel did that for their shocks they supplied to Ford

[sah62]

A possibility - Gabriel did that for their shocks they supplied to Ford

Apparently Dole did have a manufacturing plant in a city whose name began with "H" (Hanover, IL). Still nothing on "K", though.

http://archives.chicagotribune.com/1968/12/17/page/59/article/assure-new-center-for-dole-valve