I did find the numbers on the A.I.R. injection pump on the machined cut -out as you described. They are 4281S; so as I read it it should be the 42nd day of 1968, 1st shift, model S. On my 69 the number is 01681S. Question: Do these pumps go out of a 6 month before build window? So, if I have an early 69; would an early 68 dated pump be within the range for my vehicle?
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Re: A..I.R. Pump: Terry Mc
Mark, you are reading the dates exactly as I would read them. We typically give them the usual six month window. In the case of your early 1969 I would base my assessment of the originality of the AIR pump on hos well it flows with the rest of the engine compartment. Given the change in AIR pump models from 1968 to 1969 there could have been a non typical inventory situation at the assembly plant. I am not sure all judges would take the same point of view, however.Terry -
Re: A..I.R. Pump: Terry Mc
Thanks Terry! This helps a lot. The production date on my 69 is 1/28/69; so there is a bit of a gap. The other components seem to fit in with normal sequences. Sincerely, MarkComment
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Re: A..I.R. Pump: Terry Mc
Mark-----
The 1968 pumps all have an external pressure relief valve on the pump's aluminum housing.
The 1969 pumps have no such relief valve (except L-88/ZL-1 which use the 1968 style pump).
Below are photos of an NOS 1968 (and 1969 L-88/ZL-1) pump (manufactured the 256th day of 1968) and a photo of an NOS 1975 pump (manufactured the 225th day of 1974). The 1975 pump is identical in external configuration to the 1969 pump except for the configuration/color of the centrifugal filter ("fan"). I have an NOS 1969 pump but it's harder for me to get at.
Note, in particular, the configuration of the boss on the top of the pump housing on the 1975 pump. This configuration is the same for 1969-75 pumps but different for later pumps.In Appreciation of John HinckleyComment
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Re: A..I.R. Pump: Terry Mc
Joe: Thank you very much for the pictures and explanations. They are helpful.. I believe that I have two 69 pumps. My only isse is that the pump on my car is outside the 6 month window. Sincerely, MarkComment
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Re: A..I.R. Pump: Terry Mc
Mark,
Is your corvette mostly original, restored or some place in between?
Do you think the pump on your car might be original to the car?TerryComment
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Re: A..I.R. Pump: Terry Mc
Terry: The car is mostly original. I purchased it from the late Jim Adams; and I remember when he purchased the car, it looked fairly untouched. I guess it is possible that the pump could have been replaced; however, from all the other parts, it seems to fit in. Do you kow if most of the pumps fit in close their producton date? Sincerely, MarkComment
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Re: A..I.R. Pump: Terry Mc
I generally let the car tell me the originality of the part. Of course that doesn't work with restored cars. It sounds like it might be original in your case.
I have some data on some pump dates, but I will have to dig deep into my home computer files. This is a though week for spare time, but if you don't hear from me in a week or two send me a PM to get me back on track. I am kind of curious myself.TerryComment
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Re: A..I.R. Pump: Terry Mc
Terry: Thanks for all th extra effort on this cause! Sincerely, MarkComment
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