[TPM]

Has anyone purchased and installed the M/E Adjustable PCV valve? I'm wondering how it will work in my 1965 Tri-power...

[Tom Vaught]

Someone else started a thread on that same M/E Adjustable PCV valve and I posted info on why you need a specific flow (designed in by the carb manufacturer with the data supplied to the PCV Manufacturer for GM Vehicles. Same deal for Ford Vehicles and Chrysler vehicles.
Each company has a PCV Guy who conducted testing of his part in conjunction with the carb manufacturer. With EFI Engines the same deal applied.

A V-8 engine wants idle airflow between 16 and 19 cfm for most V-8 engines. Most PCV valves are designed to have a max flow no greater that 4 cfm and on average less than 3 cfm.
So then the carb people calibrate their idle air flow and throttle blade positions based on that extra leakage into the intake manifold but with contaminated air (Corrosive Combustion Gas) from the engine. So now these people want $$ for a part that people will mess with, screw up the operation of the carburetor, (Air/Fuel Ratio WRONG), and when the engine does not run properly blame it on everything but their adjustable part that most people have NO BUSINESS WHATEVER ADJUSTING.

But if you want to buy that part vs a properly designed factory part, go for it.
From their website: "Furthermore, it is difficult to obtain proper flow data to determine which stock style valve (if any) is correct for a modified application." What is this IF ANY BS. PCV Valves have been required for over 60 years as part of the Emissions System vs a Road Draft Tube. And the "difficult to determine flow data deal" just means every vehicle has a specific part number/calibration for that basic engine so sure you can't use generic flow data and apply it. So they give you a screw to turn and say go play Emissions Engineer.

Tom V.

[TPM]

So then maybe I should ask does anyone know where I can get an oem PCV valve for a 1965 tri-power?

[Tom Vaught]

In the Parts Book is a listing for PCV valves for a given Pontiac application. In your case 1965 Tri-Power.
Do you have a 65 PCV valve on your engine right now?

In reality stock PCV valves do not wear out.
They might get dirty and oil contaminated a bit, but a nice washing in some cleaning solvent in a wash tank, and you are good to go again for thousands more miles. The PCV valve shuttle floats between open and partially open conditions. The only time it actually closes if you get a backfire condition. If you have high vacuum the shuttle is in one position, as the vacuum drops it moves to the position the engine vacuum tells it should be at vs the calibrated spring inside the valve. WOT throttle and the
valve does not add much crankcase fumes to the intake and pressure from poor ring seal causes the crankcase to go slightly positive pressure. If you have closed breathers and a hose to the air filters the pressure goes to the Tri-Power air cleaners.
If a 49 state 65 GTO, the pressure goes thru the valve cover breather, hopefully a good breather and does not push oil vapor out of the engine.

Tom V.

[TPM]

I have a PCV valve that is correctly hooked into the hose that runs from TriPower manifold, but I don't know if it the correct one for my engine

[Tom Vaught]

PCV Valves have a number on them.
Maybe we can match it up to the Pontiac Parts Book.

Tom V.

[Tom Vaught]

http://mewagner.com/?p=1130

Have you ever seen a vacuum applied to a large tank or a gas tank. The gas tank goes from normal size to the size of a shoe box due to atmospheric pressure on the other side of the oil pan.

So if their pan operates 99% of the time under a vacuum at wot. And at WOT the vacuum is basically zero flow to the engine. 99% of nothing "0" is what number?

Tom V.

[TPM]

Looks like number on my PCV valve is 2020

[64speed]

I just bought the pcv valve for a 73 grandville cause that’s what the motor came in even though I only am using the block. I guess my holley efi will tune it out

[Tom Vaught]

You will be ok with the "pcv valve for a 73 grandville cause that’s what the motor came in even though I only am using the block" because the block somewhat sets the displacement of the stock engine. 326, 389, 400, 421, 455 are all series of blocks. And yes the EFI will adjust to pcv flow in the intake manifold. Once it learns.

The PCV SYSTEM is a very important part of your engine as it removes the corrosive gases in the oil pan that killed all of the Model T and Model A engines in less than 15,000 miles. A smart group of Engineers came up with the Road Draft Crankcase Purge system that worked well but dumped the corrosive gases into the air we breathe. The PCV System takes the corrosive gases and burns them in the engine. A PCV valve flows about 3 cfm on average. A carb at WOT flows 750 cfm. At 25% power about 180 cfm. So 3 cfm divided by 180 cfm is about 1.5% of the volume is PCV volume going into the engine. At higher speeds and flow but not WOT, 3 cfm divided by 600 is about 1/2 of 1% of the volume going into the engine. So the PCV system does not harm performance or power in any way.

Some people just like to buy SNAKE OIL from SNAKE OIL SALESMEN at $$$ prices.

Tom V.

[Blued and Painted]

I replaced a Fram 2020 PCV with a delco CV881C.
Don't know if the old valve was worn or out of calibration. But idle vacuum came up half a point and the mixture screws became more responsive.

Note/ The delco valve is listed to fit the GM 151 iron duke among others. It's physically the same size as the Pontiac.

Apples to apples, a 4 cyl will have less vacuum than a v-8.
So I reasoned this valve would better fit my lumpy cam application. I could be all wet but the 6 dollar valve off amazon was a good investment IMO.

Results may vary.

--

[Half-Inch Stud]

A long time ago, my eyes stopped stinging when i re-established the factory PCV circuit. Mine eyes had seen the glory.

[TPM]

So does anyone know the number for the correct PCV valve for my 1965 tri-power?

[Tom Vaught]

Originally Posted by TPM

So does anyone know the number for the correct PCV valve for my 1965 tri-power?

Bill Ryder over on the 64-65 GTO forum posted this up based on my request to try to help you. Lots of good info here.

http://forums.maxperformanceinc.com/...39#post5241539

Tom V.

[coonhunter70]

ebay Is a good place to find NOS pcv valves, I use the AC cv679 in a 455. I don't trust todays foreign made one size fits all auto zone stuff!

[lust4speed]

I was just going to mention that the stuff being imported is terrible, and that includes many of the new valves stamped Delco. Some won't rattle when shaken and others you can blow through either end with exactly the same resistance. Had one of our club members that was leaving a smoke trail behind his GTO until we capped off his PCV hose and exhaust totally cleared up within a few miles. I wonder if this isn't why the guys are able to market the cure-all adjustable valve. One or two attempts at installing bad PCV valves and owners are ready to try anything.

[Tom Vaught]

The GOOD OEM Suppliers were able to make a GOOD Functioning Positive Crankcase Ventilation Valve for about $6.00 and even with things costing 4 times what they did in the 60/70s, PVC Valve today would cost $24.00 no way would I ever give people $129.00 for a part when most likely the old $6.00 part would do the job better.

No Plastic Parts in the old valves, just a spring and shuttle in a steel housing. Wash it out and good to go for another 50,000 miles.

Tom V.

[68 Firebird]

I had issues with a few from Advanced and Autozone.(RATTLED AT IDLE)
Bought a NOS off Ebay and could notice difference.
Finding GOOD parts for our cars is harder and harder!!

Gerry