PCV valve 5649561

[Don E.]

Re: PCV valve 5649561

David, good point. I went through my copy of the 62 assembly instruction manual (AIM) and found very few other items that were hand written. 242 is a 2 page item and both pages have the hand written notation for the valve. It only says "was 1552729" and indicates on the drawings as item 3 the 5649561 valve. All pictures indicate that it was a serviceable valve as was 1552729. After all this, I have my doubts if 5649561 exists.

[Joe L.]

Re: PCV valve 5649561

David, good point. I went through my copy of the 62 assembly instruction manual (AIM) and found very few other items that were hand written. 242 is a 2 page item and both pages have the hand written notation for the valve. It only says "was 1552729" and indicates on the drawings as item 3 the 5649561 valve. All pictures indicate that it was a serviceable valve as was 1552729. After all this, I have my doubts if 5649561 exists.

Don------


What's the date in the revision block to the left of the "was 1552729"?

[Don E.]

Re: PCV valve 5649561

revision date is 12/6/61.

[Joe L.]

Re: PCV valve 5649561

revision date is 12/6/61.

Don-----


That would mean the 5649561 valve was probably not used in PRODUCTION until at least mid-January, 1962, if ever.

I strongly suspect that GM #5649561, if it was ever actually released, was a PRODUCTION-only part number for a PCV valve that carried only an AC type number embossed on the valve (i.e. CV-xxxx). A valve with that AC type number may have carried a different GM "long number" in SERVICE. AC was one of the few GM divisions that was wont to do this sort of thing.

So, what was the AC type number? I don't know.

[Don E.]

Re: PCV valve 5649561

Joe, thank you for your help on this. I, as I said before, suspect this was never used on the 1962 model year, if ever. Therefore this still leaves me with my original question about what I should have on my car that will allow, if judged, me to get maximum points for this option. I doubt that there are many, if any, original 62's with rpo 242 that we can use to verify the "CORRECT" valve. Therefore, I guess my option is to install a CV-590C and live with it. Thanks again.

[Joe L.]

Re: PCV valve 5649561

Joe, thank you for your help on this. I, as I said before, suspect this was never used on the 1962 model year, if ever. Therefore this still leaves me with my original question about what I should have on my car that will allow, if judged, me to get maximum points for this option. I doubt that there are many, if any, original 62's with rpo 242 that we can use to verify the "CORRECT" valve. Therefore, I guess my option is to install a CV-590C and live with it. Thanks again.

Don-----


Why not use the GM #1552729? I believe that valve was installed on many, if not all.

The CV-590C would definitely not be correct, although probably functional. The CV-590C did not even exist until much later.

[Don E.]

Re: PCV valve 5649561

Joe, yep I could do that. It has now become the principle of the situation. NCRS needs to do some more research on this question. Thanks for your help. Don

[Joe L.]

Re: PCV valve 5649561

Joe, yep I could do that. It has now become the principle of the situation. NCRS needs to do some more research on this question. Thanks for your help. Don

Don------


Giving this some more consideration, here's what I think happened here:

First of all, as I previously mentioned, the AC Division usually used different GM long numbers in PRODUCTION and SERVICE for the same PCV valves. There were exceptions and the 1552729 was one of those exceptions, at least for awhile. The 1552729 was also a PCV valve that had that GM long number stamped on the valve. This was a practice that was pretty much eliminated by AC Division by 1962-63. During and after that period, PCV valves usually only had the AC type number stamped on the valve.

As I previously mentioned, the GM #1552729 was discontinued in May, 1962 and replaced by the GM #5646178. However, that was the SERVICE part number for the valve (which continued to be stamped 1552729 right up to the time of its discontinuation in 1966). Following AC Division practice of the time, this valve would have had a different PRODUCTION GM long number. What was that part number? I can't say for sure but I highly suspect it was GM #5649561. I believe that some folks have drawn the conclusion that since the early 1962 PCV valve carries the 1552729 stamped part number, that later should carry the 5649561 part number. But, that's a false conclusion. So, I would highly suspect that one could look for a valve stamped 5649561 for a million years and you'd never find one.

By 1963, GM was specifying the AC CV-590 (NOT 590C) as the replacement for 1962 Corvettes (even though the 5646178 continued to be available until 1966). The SERVICE part number of this valve was GM #5649689 and the PRODUCTION part number was GM #5649996. We know that this was not the valve used in PRODUCTION on 1962 Corvettes since the PRODUCTION part number is not the same as that shown in the 1962 AIM.

The only other possibility is that there was some unknown valve "in between" the 1552729/5646178, aka CV-202 and the 5649689/5649996, aka CV-590. That valve would have had the PRODUCTION part number 5649561 and unknown GM SERVICE part number and unknown AC type number. While this is a remote possibility, I HIGHLY doubt it.

So, why did the AC Division use different GM long numbers for the same part depending upon PRODUCTION and SERVICE? The only reason I've ever been able to come up with is that they used a different number depending upon how the part was packaged. For PRODUCTION, the parts were delivered to the assembly plant in bins; for SERVICE the parts were packaged in boxes. For some reason, they felt that this warranted a different part number for each even though the parts were identical. Other GM divisions also supplied parts in bins to PRODUCTION and boxes for SERVICE. However, for the most part, they used the same part number for PRODUCTION and SERVICE (unless the SERVICE part was supplied with additional parts in the package).