CV 746 C PCV valve differences
 

Does anybody know when the transition from the heavy steel to the stamped steel on these pcv valves took place? I have multiple different styles of these and thought I had a reasonably good idea of what was correct until I came across a style I didn't know existed.

I was under the impression that the heavy steel without the raised upper half was correct for 69 vehicles and that the stamped steel (dyed purple) ones were 70-up until I received this last one. I got it from a guy who had a 69 Corvette L88 car that took delivery on it in March of 69. He upon delivery transformed it into a drag car ( what he ordered it for ) and the emissions stuff was all removed day 1.

This valve which was with a bunch of parts he removed from the car seems to be a combination of sorts of both styles. It has the remnants of the purple dye on the bottom, (unfortunately a buddy started cleaning it before I saw it and stopped him) and although a different style from the earlier heavy machined pcv's I have it still has a thicker and heavier top than the later stamped steel ones I have with a slightly different profile.

I know when I showed a 69 Z28 at MCACN the gentleman judging felt the silver colored machined one was correct for it (also a March of 69 built car) but now I wonder if that's not necessarily true? Anybody have any thoughts? https://www.yenko.net/ubbthreads/pics...1_165205_2.jpg
https://www.yenko.net/ubbthreads/pics...1_165415_2.jpg
https://www.yenko.net/ubbthreads/pics...121_164456.jpg
https://www.yenko.net/ubbthreads/pics...121_164435.jpg
The pcv in the center is the style I'm questioning for 69, it has some purple dye still on the bottom that I would think it was completely covered with like the 70-up style to it's left. The machined style to the right is in a box dated July of 68 and my earliest dated box for the stamped style is 71.
Thanks, Chris

Re: CV 746 C PCV valve differences
 

----Chris,,,Bet that L88 was Monaco Orange! Do you know where the car is today. I bought its L88 twin from his best friend in 72/73. That one is in Scottsdale painted black. Mine was bought for extremely high speed highway cruising. There was an extra pumpkin next to the car that had a mid 2s gearset in it. Owner wanted to be able to run 180ish on the Mass Pike.
----Sorry I cant help you with the PCV question.....Bill S

Re: CV 746 C PCV valve differences
 

Hi Bill,
You are 100% correct! Yes I do know where it is today. I kind of thought you'd pick up on the subtle reference to the car as I knew you had the other car at one time. The guy who works with me sold it a few years back and far as I know it's @ Corvette Repair with Kevin Mackay in NY. You had Ricky's car that he ordered alongside Clarkies L88 from Crown Chevrolet in Framingham. Ricky was crazy as you were told his goal in life was to break the sound barrier on the street while Dick set his sights on the 1/4 mile.
Hopefully one of the 69 Z guys will chime in on the pcv issue as I'm pretty positive the one in the center pic is the one that was delivered in the L88 and it kind of goes against what I've been told came in 69's.
Chris

Re: CV 746 C PCV valve differences
 

I have seen conflicting info on these. Unfortunately, there are so few PCV valves that survived, as it was included in most "standard" tune ups of the day.

JohnZ may still have the original in his FG Z. Charlie may still have the original in his low mile 70 Z. I know it isn't a 69, but it would be nice to see which valve that car has.

Re: CV 746 C PCV valve differences
 

i had a friend that used to pursue these and the first pic..the one on the far right is the one that consistently brought 3 or 4 times the money the others brought...every time..i would say its the one that most people consider correct..but i dont know im no expert..

Re: CV 746 C PCV valve differences
 

3 or 4 times?

http://www.ebay.com/itm/NOS-1967-71-CORV...c6a&vxp=mtr

Re: CV 746 C PCV valve differences
 

i didnt want to exaggerate..if i said he got 800 to a grand each, no one would have believed me...

he was getting 4 or 5 hundred for nice used originals

unfortunately hes pushing up daisies ...and all of that knowledge went with him...

Re: CV 746 C PCV valve differences
 

I received this picture from Mark Bulaw from an 01B Van Nuys built 69 Z28.
Thanks Mark!
This helps . I'm hoping someone may have a reference point to the one in the middle as that seems to be a bit of a hybrid of the 2 well known styles.
Chris https://www.yenko.net/ubbthreads/pics...5-img_1786.jpg

Re: CV 746 C PCV valve differences
 

Chris, What you have in the middle is what I "Thought" to have been used sometime mid 69 (which is consistent with your L88 story) I have one just like yours and I have noticed the Font is a little narrower (look at the CV compared to the one on the left) I believe that is and production line part not over the counter.
Rich

Re: CV 746 C PCV valve differences
 

Hi Rich,
Thanks for responding. What I'm really trying to find out besides timeframe usage is if these were purple dyed, unlike the earlier machined style pcv's. Mine was definitely purple.
Chris

Re: CV 746 C PCV valve differences
 

I saw a survivior 1969 Z/28 at MCACN a few years ago with the heavier, spun steel PCV valve. Steve Shauger and Johnny K. might remember that car too. I also believe that the purple valves were 1970 and up over the counter. I personally never saw a purple PCV valve on an assembly line car but its tough remembering back that far for sure. I worked at a Sunoco and also a Hess gas station from around 67-68 to about 1971.I have seen survivor, one owner sb cars 307, 350 etc. with the heavier spun PCV valve but not sure if they were just in the early 69 model year or not. Also saw some 350 2 barrel 69 chevelles in the yards with the spun steel valves. Maybe John Karvonen and Dave Valentin can chime in here.

Re: CV 746 C PCV valve differences
 

https://www.yenko.net/ubbthreads/pics...65-photo_1.jpg

I've been using these - same style with no shoulder.

Re: CV 746 C PCV valve differences
 

The 691's are easier to find then the 746's it seem Bruce.
Cheaper too!

Re: CV 746 C PCV valve differences
 

Great topic and interesting thread. I believe like you Chris, that the flat top /spun type was 1969 production. Also I have seen the stamped raise on two late Oct 69 survivors but they may have been changed. The middle machined /raised is one I've not seen or am familiar with, but there may have been a transition period. I'll check some pictures I've take of cats built in that time period.

Re: CV 746 C PCV valve differences
 

use caution when buying ones that looks original. some on ebay have been questionable in my opinion. you can buy blue chem dye that machinists use to see lines scribed on metal. It can be had in a color very close to the factory purple dye.