691 vs 736 PCV Valve

[David S.]

Can someone explain what is correct for a 67 400hp? Should it have a hex head bottom? Dimples on the bottom? Etc...

Thanks,
Dave

[Steve B.]

Re: 691 vs 736 PCV Valve

I think the 691 is correct for 66 and maybe early 67 big blocks. It should have the shoulder on the top of the body, in other words you should not be able to see the top of the valve when installed.

[Mark D.]

Re: 691 vs 736 PCV Valve

There is an outstanding 1st design reproduction 736 on the market now. Expensive but, excellent.

[Larry T.]

Re: 691 vs 736 PCV Valve

Okay...Where can it be seen?

[David L.]

Re: 691 vs 736 PCV Valve

The photo below if from a fellow NCRS member. It is an original machined CV-736C valve from a 67 Corvette 427. I believe that the stamped steel CV-736C valves made their debut in 1968 or 1969.

Dave

[Larry T.]

Re: 691 vs 736 PCV Valve

How about the reproduction, who has those?

[Kevin P.]

Re: 691 vs 736 PCV Valve

There is a CV691C with a dated box 1967 on ExxY

[David L.]

Re: 691 vs 736 PCV Valve

There has been quite a bit of discussion about the CV-691, CV-691-C, and CV-736-C PCV valves concerning the 1967 w/427 engine in the link below.

Dave

https://www.forums.ncrs.org/showthread.php?78302-1966-JG-question-PCV-valve-label-for-427&highlight=6421981+6423695+pcv+valve

[James S.]

Re: 691 vs 736 PCV Valve

Below are pictures of a reproduction 736C PCV valve and label.



PCV Label.jpg

PCV.jpg