1963 PCV Valve

[Timothy B.]

I am looking for a nice original 1963 pcv valve to try in my car. After comparing the flow of the 590c at idle with a fixed orifice it seems the idle flow is equal to approx .100" which is quite a bit of air at idle.

I want to find a original pcv and try it to see if it's more restrictive. After looking at the Paragon repro valves, the pictures look OK but I am curious about the flow of the repro parts. I am not crazy about installing a .063 fixed orifice in the rubber hose because at lower vacuum WOT high load the flow will always be the same .063".

If there is anyone the has a nice original correct for my early 63 please email or send a private message. I have read the correct cv590 valve is approx. 2 5/16" overall length and the later valve is longer. I appreciate the help, Tim

[Chuck G.]

Re: 1963 PCV Valve

I am looking for a nice original 1963 pcv valve to try in my car. After comparing the flow of the 590c at idle with a fixed orifice it seems the idle flow is equal to approx .100" which is quite a bit of air at idle.

I want to find a original pcv and try it to see if it's more restrictive. After looking at the Paragon repro valves, the pictures look OK but I am curious about the flow of the repro parts. I am not crazy about installing a .063 fixed orifice in the rubber hose because at lower vacuum WOT high load the flow will always be the same .063".

If there is anyone the has a nice original correct for my early 63 please email or send a private message. I have read the correct cv590 valve is approx. 2 5/16" overall length and the later valve is longer. I appreciate the help, Tim

FWIW, Tim, I've looked at flea markets, EBAY, etc., for many years looking for an elusive 590 PCV valve. I've never found one for sale.

To go one step further, I've never even seen one on any car I've looked at.

Chuck

[Gary P.]

Re: 1963 PCV Valve

There was one on e-bay 6 months cv590 Black, I think it went for 75.00

[Timothy B.]

Re: 1963 PCV Valve

Chuck, Gary,

There is one on ebay now but it looks like the longer version that's described in the archives as 2 9/16" long. If that's the correct valve I would like to try it but I am not sure. Even the Paragon repro looks like the shorter version but not sure how the repro part flows air.

Chuck, What type of valve do you usually see on other 63's?

[David L.]

Re: 1963 PCV Valve

Tim,

According to my notes I had 3 "CV590" PCV valves back in January 1992 but apparently sold them years ago. I did some research back then and found the following:

1963 Chevrolet Parts Catalog (Oct. 1962)
GM #5649689 (CV-590)
62 PASS. CORVETTE w/closed vent. (8 cyl.)(exc. 283)
63 ALL, CORVETTE (8 cyl.)

1965 Chevrolet Parts Catalog (Oct. 1964)
GM # 6421239 (CV-590)
65 Ser.10 thru 30 (exc/ closed vent., H.D, A/CL)

According to Chevrolet Parts History
5649689 replaced with 6421934 in Jan. 1966
6421239 replaced with 6421934 in Aug. 1965

Enclosed is a photo of a NOS 6421934 PCV valve, stamped CV-590C" (box dated "6 68") on the left ("stamped" steel type).
On the right is a used "solid" steel type PCV valve stamped "CV 590C".
Both PCV valves measure about 2 9/16" overall length. As best as I can remember I believe that the "CV590" PCV valve was shorter but I have nothing in my notes.

I can not explain why the CV590 valve ("solid" steel type) had two different GM part numbers.

How do you measure the flow thru a PVC valve?

Dave

[Chuck G.]

Re: 1963 PCV Valve

Chuck, Gary,

There is one on ebay now but it looks like the longer version that's described in the archives as 2 9/16" long. If that's the correct valve I would like to try it but I am not sure. Even the Paragon repro looks like the shorter version but not sure how the repro part flows air.

Chuck, What type of valve do you usually see on other 63's?

I see the 590C, Tim.

Chuck

[Timothy B.]

Re: 1963 PCV Valve

David,

The only way I know to measure flow is to compare the idle RPM with the valve installed to a fixed orifice. In my case it seems the same at approx .100" I am using the AC cv590c crimped valve now but I would like to see if the original 590 flowed less at idle rpm.

Other than that, measuring crankcase vacuum at idle through the dipstick tube with everything plugged may give a idea if the valve is sized correctly for the engine. Other than that I have no idea.

[David L.]

Re: 1963 PCV Valve

Tim,

I never really understood why there were so many different PCV valves. I also have a NOS CV735C PCV valve ("solid" steel type) for a 68-69 Pontiac Tempest 6 cyl. in a box dated June 1968 that appears to identical to my used "solid" steel CV590C PCV valve except that the hose end is for a 3/8" hose. The hose end diameter on the CV590C valve is for a 1/2" dia. hose.

Do you know anything about the "CT-1 TEST SET", etc., as shown in my 2nd photo from the AC PCV specification chart (June 1969)?

Dave

[David L.]

Re: 1963 PCV Valve

David,

The only way I know to measure flow is to compare the idle RPM with the valve installed to a fixed orifice. In my case it seems the same at approx .100" I am using the AC cv590c crimped valve now but I would like to see if the original 590 flowed less at idle rpm.

Other than that, measuring crankcase vacuum at idle through the dipstick tube with everything plugged may give a idea if the valve is sized correctly for the engine. Other than that I have no idea.

Tim,

Just as you mentioned the dipstick tube I remembered the reason why there was a dipstick change for the 1964 models. The problem was the dipstick seal. The 1964 Corvette dipsticks are the same length as the 1963 dipsticks except for the seal. I have owned NOS & original 1964 dipsticks with a "rubber cup" style seal as well as ones with a metal "bell shaped" style seal. I don't remember where I got the following information but here it is:

"With the 1963 system, the PCV system was drawing air through the poor seal at the dipstick. The new design corrected the problem."

I believe that the CV590C PCV valve possibly made it's debut in the 1964 ( or maybe it was 1965 ???) model year. The September 1964 issue of "Chevrolet Service News" (page 25) states the following: "All engines use the new self-cleaning crankcase ventilation valve shown in figure 34. This ventilation valve has small clearances between the valve and the passage and as the valve moves back and forth, it cleans itself."

Dave

[Joe L.]

Re: 1963 PCV Valve

Do you know anything about the "CT-1 TEST SET", etc., as shown in my 2nd photo from the AC PCV specification chart (June 1969)?

Dave

Dave------


It's an AC-supplied tester which is used to test PCV valves for proper operation. It came in a metal box with various tubes, adapters, instrument, etc. I believe the numerical reference in the column denotes the adapter to be used for any specific valve. Somewhere around here I have an NOS CT-1 (or, CT-2 or CT-3). However, at the moment I don't recall just where it's at.

[Timothy B.]

Re: 1963 PCV Valve

I am certain the pcv valve is mentioned in the 1963 shop manual but the test mentioned may only be the idle rpm drop method where it stated to place your finger over the valve end and if engine rpm drops less than 50 rpm the valve should be replaced.

Other than that as I mentioned before, checking vacuum at the crankcase through the dipstick tube is the only other test I can think of. The crankcase needs a negative pressure for efficient engine operation.

At WOT the negative pressure (vacuum) is at it's lowest but the spring inside the valve pushes the pintle to form a wide open path for the engine to breathe in any crankcase vapors. If for some reason the flow reverses which I don't understand why, the closed system will ingest crankcase vapors through the other end which is into the air cleaner through the front on a 63.

My issue is idle air flow as I believe this valve flows to much air for the 300hp at idle just like the open choke tube for the hot air intergal choke. At idle, what is considered correct vacuum on the crackcase for a pcv?

[Chuck G.]

Re: 1963 PCV Valve

Chuck, What type of valve do you usually see on other 63's?

I see the 590C, Tim.

Chuck

Tim, after reading back through this thread, I realized that I really didn't answer your question adequately.

What I SHOULD have said is I commonly see the 590C, the black phosphated version without the rim, like the one on the RT side in David's picture.

Chuck

[Timothy B.]

Re: 1963 PCV Valve

Thanks Chuck,

I appreciate the information. I guess the correct valve should be stamped cv590 with no c and shorter.

If anyone has one can you post a picture?

[David L.]

Re: 1963 PCV Valve

I specifically asked if the PCV valve in the Ebay auction listed below was stamped "CV590" or "CV590C" and was told "CV590" and measured 2 9/16" long.

Does this mean that there was a long and a short "black solid steel" CV590 PCV valve?

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=280711363744&ssPageName=ADME:X:RTQ:MOTORS:1123

[Jim B.]

Re: 1963 PCV Valve

Tim---here's a CV-590 on a spare '63 F.I. unit that I have. It's not real clear, but it's stamped CV-590, with no "C" after the "590".