1968 Smog Pump Systems
I've got a relatively early # 04136 (D 08) 1968 427/435 convertible and have a couple of questions about the Smog (A.I.R.) Pump. It's part # is 7801149 and date code is D17. Was this pump # used on just 427's and if so on which ones? If I'm reading the date code correctly, the pump body was cast in April of 1967. I was wondering why it would be so early for a car assembled in November of 1967. I know the diverter valves were provided by the Rochester Division. Were the pumps provided by them as well ? Thank You
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Re: 1968 Smog Pump Systems
I don't think pumps with that back plate casting number were used before 1970. -
Re: 1968 Smog Pump Systems
Where did you find the #7801149 and the date?
For the pump stamped assembly number, if the pump is installed on the car, stand on the driver's side juSt at the front of the DS front wheel and with a dental mirror reflecting back toward you -- look at the bottom rib (or bulge) of the aluminum part of the pump. You will find a machined semi-circle here with some numbers and letter stamped in it -- or in your case likely just in front of it. Those of us who have been doing this a while know where to look, but you might want to first feel in this area to find the machined surface. Let us know what numbers and letter you find and we can decode it for you.
Alternately the easy way is to look in the 1968-68 TIM&JG for the picture that will show you what to look for, and where to look. It will also give you the key to the codes you will find on the pump. I would cite you a page, but I don't have my manual at work.TerryComment
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Re: 1968 Smog Pump Systems
The part # and date code were embossed into the rear cover casting which I now realize are just for that part. Looking in the area that you suggested revealed a very small stamping reading 28671Y. Any information you can provide me would be
appreciated. Thank YouComment
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Re: 1968 Smog Pump Systems
286 day of 1967Comment
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Re: 1968 Smog Pump Systems
Thanks Graeme. That makes sense. So using a calculator and a calender I come up with October 13th, 1967. The build date is November 8th so that falls into line. I'm assuming that the Y stands for the designation by GM as the Corvette being the Y body. Is there a part number anywhere on the pump itself ? Is just this basic pump assembly (without the pulley or diverter valve) used on all the Corvettes with the specific appication (eg 327,427) determined by the pulley and diverter valve ? Is there anything that would identify this unit as being used for an L71 427/435 engine? Thank YouComment
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Re: 1968 Smog Pump Systems
The number 1 is either the first shift or the #1 assembly line. The letter Y is the series of the Saginaw built pump. It is just a coincidence that you found it on a Y-body car. This series was used on many other GM vehicles of the period and for many years. I am told there is a casting number on the pump body behind the pulley. I would be surprised if there was not a casting date someplace on the pump as well, but it is not visible on the assembled pump. But then you know the assembly date, so what does the casting date mean anyway?
There is a stamped pert number on the diverter valve, and we do our best to describe its location in the TIM&JG -- but it is easiest to see with the diverter valve separated from the pump and elbow (if present). It is stamped into a flat area much like the Rochester carburetor stampings. That stamped number is, I believe spelled out in the TIM&JG and is probably unique to Holley 3-barrell equipped engines. I would have to look up those numbers to be sure and it is now way past my bed time. There is some work for you.
There is nothing that is going to tie that pump to your specific car, and several vendors sell complete AIR systems that will appear to the untrained observer to be TFP for your car using rebuilt parts from other cars -- some of them not necessarily Corvettes. There are very few parts that are unique to Corvette. Remember it is just a Chevrolet and every item the engineers can use on other GM products reduced the cost or increased the margin or both.TerryComment
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Re: 1968 Smog Pump Systems
Thanks Terry, The number stamped on the diverter valve base is 28296. The entire Smog System was removed in 1985 so I can examine each component under good illumination on my workbench. The smog pump, pulley, diverter valve, mounting bracket, brace and all hardware were removed as a unit. None of the fasteners holding the pump together or attaching the pulley and diverter valve are still factory intact. It still has the dirt, grease and sloppy factory paint from just off the car removal as well. For this reason I'll curtail any further disassembly of this pump assembly. As you men-tioned Terry there are many "craftsmen" who cobble together parts from many sources and "restore" them into a "like new" system. The problem their is that everything has to be refinished to match and thus has to be "like new". The
system worked just fine when I removed it, so I'll just keep it as-is unrestored . Thanks for your help.Comment
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Re: 1968 Smog Pump Systems
I think I worded the fastener issue wrong. I meant to say that they are all untampered with since leaving the factory.
Terry, I would really appreciate the diverter valve number application if you have time. ThanksComment
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