63 PCV valve question

[Edward J.]

Which CV590C valve is correct for 63, I have a older GM replacement I believe which is silver and reads- AC spark plug with CV590C part no.and there is a black colored reproduction one , Does anyone have a pick of a real deal PCV valve.Was there a early and late production valve, Is that why they have the two different colors/ Thanks for you input. Ed

[Ronald L.]

Re: 63 PCV valve question

Ed, I thought we covered this in August pretty good...

From the earliest PCV's to about 64 +/- they were black. The real 63 590 valves did not have the C. Then, in 65 for sure the valves were still solid machined steel but zinc plated. Then +/- 1968, perhaps for the start of 68 MY in late 67 they were combo stamped steel lowers and machined tops. By 69 fully stamped construction, where the design would permit such as the 691 and 736. The 726 for the 327 was different and not adaptable to the newer lower cost technology, so that one is plentiful in the machined zinc version.

What we don't have is the print to tell you when the part changed to a C version, probably consistent with the change to zinc plating the valves.

[Edward J.]

Re: 63 PCV valve question

Thanks Ron. how do the repro's match the originals? does anyone know.

[Ronald L.]

Re: 63 PCV valve question

Edward, I think there is a difference in the crimp over, can't tell on the font & embossing that would require side by side comparison and I don't have a repro to compare to the original; something like this - original if you are a purist.