1964-65 250/300 Carb PCV Restrictor Fitting

[Page C.]

While working on my late July 1965 327/300 I had a chance to take a few photos of the 90 degree restrictor and adapter that screws into the rear of the Carter AFB. I could find only one post in the archives about these fittings and no pictures. They are both made of bronze and differs from the one shown in the new 1965 JG in the material and shape. The adapter (GM# 444000) is 3/4 ATF and the hex part is 5/8 in length and the overall length is 1 1/4 inches. The thread is 1/4 18 pipe thread. The 90 degree fitting (GM# 3853720) has a .102 restrictor hole and a logo on both sides as pictured. I believe this setup was used instead of a PCV valve across other GM engines doing the 1964-65 model year and probably multiple suppliers.

[Jim D.]

[Joe L.]

Re: 1964-65 250/300 Carb PCV Restrictor Fitting


Jim-------


Functionally they appear identical. So, the difference in configuration is likely the result of manufacturing differences between different suppliers, an optional configuration shown on the GM blueprints or a change in the blueprints at some point. The one thing that is curious, though, is the lack of the "GM" trademark on yours. If that is required on the blueprint, as it often is, then it should be on both parts regardless of other differences.

[Jim D.]

Re: 1964-65 250/300 Carb PCV Restrictor Fitting

Joe, Those are the fittings that the car left the factory with. It appears that neither adapter (Page's or mine) has a "GM" trademark so obviously not everything has the trademark. I don't have the latest JG, what does it say about them since Page states his fitting differs from the guide?

[Joe L.]

Re: 1964-65 250/300 Carb PCV Restrictor Fitting

Joe, Those are the fittings that the car left the factory with. It appears that neither adapter (Page's or mine) has a "GM" trademark so obviously not everything has the trademark. I don't have the latest JG, what does it say about them since Page states his fitting differs from the guide?

Jim------


I have no doubt those are the original fittings. As I mentioned, the difference might be just a difference in suppliers with multiple suppliers used.

The adapter is more of a "standard" type part and the GM blueprint may not have specified that such an embossment be placed on it. However, the other part is a highly specialized piece with a Chevrolet part number. For it to be on one of the parts indicates that the requirement for it must have been on the blueprint. The fact that it's not on the other is curious but, in no way, am I implying it's not an original piece. I quite confident it's original.