Smog Pump Date Code
 

This is the smog pump from my 73 Z28. No idea if it's original or not. The stamping reads 10231S....the 3 is barely visible, but it's there. Anyone have a clue what the stamping deciphers to?

102nd day of 1973. Thursday, April 12th. Does that fit with your car?....Joe

Is the smog pump installed at engine assembly or at Norwood? My engine was assembled February 20th, Trim Tag assembly date is 1st week of April. Not sure that Trim Tag date reflects actual production, because I'm confident that the rear axle is still original to the car and it's also dated April 12.

The pump was installed at the vehicle assm plant. The Fisher Body tag reflects a projected date. A NCRS page would tell you the actual assm date of the vehicle. From what you've posted, I would think the pump was original to the car.....Joe

Thanks very much, Joe. Based on that info, I would tend to agree with you that it's original to the car. Per all the original paperwork I have for the car, the OO special ordered it in January of 73 and took delivery late in May of 73.

I didn't think the NCRS records went into 1973 :dunno:

I didn't think the NCRS records went into 1973
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You're right. I didn't see that....Joe

FWIW....Using interpolation based on production records from the Nasty Z28 site, my car should have been produced on or about April 19th.

Alwas thought the"1S" suffix meant Chevrolet?
Pic 1 is Jan 24 1969
Pic 2 is 46th day of 1972

Could be. Obviously both of yours have that, mine has it, and one that was just sold on this site also has it. Thanks for the pics, Dave :biggthumpup:

Date code breakdown
 

Per CRG:

That's great info Marty!
Here's an example of a '67 pump, note that the "0" is lightly stamped.
054th day of 7 with a Tonawanda stamp of T0330

A few more.

Pic 1 is 68 or [R] type. [valve]
Pic 2 is 69- or [S] type [no valve]
Pic 3 is marking on pump in pic 1. 10th day of 73 so a replacement??? It is NOS
Pic 4 is marking on pump in pic 2 157th day of 69


Pic 5 is 77th day of 69 and is [S] type but marked [U]???
Pic 6 is 105th day of 72 and is [S] type but marked [W]????

Have read posted info before but these odd, marked ones are not rare at all. That is why I have always thought the [1S] was 69- up Chev.

Always looking to learn.

Are we anal, or what? :haha: Back in the day, the only thing we cared about smog pumps was how quickly we could remove them and throw them in the dumpster.

Guys i have a used smog pump, 7801149 but i have no stamped date code i can find. I read GM may have eliminated the date codes after the 69 models. I looked at all the flat machined surfaces and wire brush with a good rust oil and still no codes anywhere. It has the black fan and it looks like a original GM pump. Any ideas?

Well, as evidenced by many of the examples in this thread, GM did not eliminate the date codes after the 69 models. Could be a warranty replacement or just didn't get stamped.

Take the black fan off they have a date molded into it

Thanks i will try that.

That is what i thought too. Warranty replacement or never got stamped.