PCV Valve Question -Types / Letter Designations

[Al P.]

I am trying to match the correct PCV valve to my modified Tri-powered BB 427. My(long duration/high overlap) solid cam produces only 8-9 inches of vacuum at idle so its far from the stock L71/89 configuration. Its more like an L88 in performance. I need to install the correct PCV valve...

I know that the PCV valves for our 67 BB's look the same - but I'm trying to determine what the letters designate on the PVC valve "plunger" inside it.

If you look at your PCV valve upside down you will see that little plunger (when you shake the PCV valve - you hear the plunger rattle). Each one has like a "D" or "F" etc.....

Can anyone define the letters and associated idle vacuum settings for each?

What PCV valve was used in the 67 L88? What letter on the plunger did that one have. Or the Purolator or Fram PCV number?

Appreciate the help here.

[Joe L.]

Re: PCV Valve Question -Types / Letter Designations

I am trying to match the correct PCV valve to my modified Tri-powered BB 427. My(long duration/high overlap) solid cam produces only 8-9 inches of vacuum at idle so its far from the stock L71/89 configuration. Its more like an L88 in performance. I need to install the correct PCV valve...

I know that the PCV valves for our 67 BB's look the same - but I'm trying to determine what the letters designate on the PVC valve "plunger" inside it.

If you look at your PCV valve upside down you will see that little plunger (when you shake the PCV valve - you hear the plunger rattle). Each one has like a "D" or "F" etc.....

Can anyone define the letters and associated idle vacuum settings for each?

What PCV valve was used in the 67 L88? What letter on the plunger did that one have. Or the Purolator or Fram PCV number?

Appreciate the help here.

Al------


There was no PCV valve used on a 1967 L-88; 1967 L-88 used a road draft tube for crankcase ventilation. However, 1968-69 L-88 used an AC CV-746C PCV valve, and that's exactly what I recommend you use for your application. In fact, regardless of valve calibration and operating characteristics I don't think there's another valve that would be configured for your application that would do you any better than the CV-746C. This valve, GM #6484525, is GM-discontinued but it might still be available through Delco dealers or an aftermarket equivalent.

A Standard Motor Products (SMP) V-160 is equivalent to the AC CV-746C.

[Al P.]

Re: PCV Valve Question -Types / Letter Designations

Al------


There was no PCV valve used on a 1967 L-88; 1967 L-88 used a road draft tube for crankcase ventilation. However, 1968-69 L-88 used an AC CV-746C PCV valve, and that's exactly what I recommend you use for your application. In fact, regardless of valve calibration and operating characteristics I don't think there's another valve that would be configured for your application that would do you any better than the CV-746C. This valve, GM #6484525, is GM-discontinued but it might still be available through Delco dealers or an aftermarket equivalent.

A Standard Motor Products (SMP) V-160 is equivalent to the AC CV-746C.

Thanks Joe!