Interpreting smog pump dating

[Mike E.]

Any ideas on how to date this one? It doesn't fit with what's spelled out in the JG. If you find it hard to see, it is 5211S

[Paul O.]

Re: Interpreting smog pump dating

Mike

It would work out like this with the numbers present 52 day 1 for 71( could be 81, 91) but its condition could tell you if its original to the car I think 1st shift and S an internal code or plant.

[Dick W.]

Re: Interpreting smog pump dating

Mike

It would work out like this with the numbers present 52 day 1 for 71( could be 81, 91) but its condition could tell you if its original to the car I think 1st shift and S an internal code or plant.

S is for Saginaw as I understand it.

[Mark D.]

Re: Interpreting smog pump dating

I would say S is for the pump model. S would indicate a pump without the external pressure relief.

[Terry M.]

Re: Interpreting smog pump dating

I would say S is for the pump model. S would indicate a pump without the external pressure relief.

But they were cast in Saginaw -- there is a "S in a box" logo on them somewhere -- I have seen it, and not when I was on the pipe.

[Loren L.]

Re: Interpreting smog pump dating

I have 2 AIR pumps on hand. One is 5696211 (66 ElC 396 with A/C, Fremont CA build) stamped 30251A, which I decode as 302nd day of 1965, lst shift & "A" as Unknown. The second is a 1967 pump stamped 07671S that I feel reads 076th day of 1967, 1st shift and "S" as Unknown. Could "S" indeed = Saginaw and "A" =s another assembly plant location?

[Mark D.]

Re: Interpreting smog pump dating

But they were cast in Saginaw

I agree but, it is my belief the S designates the pump model. Anybody got a 68/69 smog pump on their L88 (with the relief valve on top)? What letter is on it? Y?

[Bob J.]

Re: Interpreting smog pump dating

Piper, like this?

[Paul O.]

Re: Interpreting smog pump dating

But they were cast in Saginaw -- there is a "S in a box" logo on them somewhere -- I have seen it, and not when I was on the pipe.

Terry

Like this photo.

[Mark D.]

Re: Interpreting smog pump dating

Piper, like this?

Yup...just like that.

Funny, that one's from Saginaw, too.

[Terry M.]

Re: Interpreting smog pump dating

I agree but, it is my belief the S designates the pump model. Anybody got a 68/69 smog pump on their L88 (with the relief valve on top)? What letter is on it? Y?

I have seen charts from Chevrolet that indicate the S IS the model indicator -- just as the Y is in your post and the A is in Loren's. I merely wanted to point out that I had seen the S in the box with two rounded sides cast into the aluminum part of the AIR pump casting. I can't tell you where I saw it. Maybe at Saginaw Metal Castings as they were being made.

[Terry M.]

Re: Interpreting smog pump dating

Terry

Like this photo.

Bingo.. Ding, ding. Paul is the winner.

[Joe L.]

Re: Interpreting smog pump dating

Mike

It would work out like this with the numbers present 52 day 1 for 71( could be 81, 91) but its condition could tell you if its original to the car I think 1st shift and S an internal code or plant.

Paul------

The alpha character at the end of the series represents the pump model.

1966-67= "A" (and, possibly, other codes, too)

1968 (GM #7803947 with relief valve)= "Y"

1968 and 1969 L-88/ZL-1 (GM #7806686 with relief valve)= "S"

1969-74 (GM #7803948 no external relief valve)= "S"

1975 (GM #7817575 no external relief valve)= "S"

1976-78 (GM #7817809 no external relief valve; different configuration than 69-75)= "S"

The first 3 digits of the stamped code represent the julian date. The 4th digit represent the last day of the year. The 5th digit may be a shift identifier. The final alpha character is pump model.

Attached are photos of an NOS GM #7806686. Note that the first 3 digits of the code are very lightly stamped and may be difficult to read.






DSCN2834.jpgDSCN2835.jpgDSCN2836.jpgDSCN2837.jpg

[Matthew G.]

Re: Interpreting smog pump dating

I know Mark Gorney did a tremendous amount of research on the 66 and 67 Original California A.I.R. systems. To my recollection, Gorney was fairly adamant that 66 and 67 REAL "T" fitting Corvette pumps ended in a "P". I personally have 3 pumps from 66 and 67. 2 are Corvette and 1 is Chevelle/Nova/Camaro. Both Corvette pumps have the T fitting and the date stamp ends in "P". The late 65-dated Chevelle/Nova/Camaro pump ends in an "A". All have the Saginaw "S" stamped into the pulley-side facing. Happy to send pictures to anyone interested.

[Matthew G.]

Re: Interpreting smog pump dating

Sorry about the QUOTES......darn IPad!