PVC Valve in a 308

Browniepetersen

Was having a discussion the other day with a friend and he mentioned that I should install a PVC valve in my 308. I guess I have two questions: First, for those of you that have done this, what is your opinion. And, second: How do I do this for the best effect on my 308?

MikeWA

First thought that comes to mind is "If it ain't broke, don't fix it."

bent metal

I wouldn't install that kind of plastic in my car. But I might install a PCV (positive crankcase ventilation) valve.

Ol racer

I had PCV valves in my Hudson's for Yrs. I insert the Valve from a GM into a shortened Draft Tube then run a vacume hose up to the Intake. I use a Mopar type Breather Cap with a Nipple to run another hose from Cap to an AirFilter. Some filters ive drilled a hole in the base, others I wired the 'breather hose' to the Filter.

RL Chilton

Uhhh . . . . what the hell for? There's no reason to out-think the Hudson engineers.

[Deleted User]

As far as benifit / reason to do such a thing ( I have not myself but hear guys talk ). It will lower the presure in the crankcase if not pull a slight vacume. Thus removing the well known tendency for the Hudson mains to seep.
I agree it is not as designed but might be a reversible stop-gap measure till a rebuilt is cost effective,
Roger

SuperDave

If you put air into the intake manifold, you lean the fuel mixture. Inless you compensate for that with different jetting, you could set up a burned valve situation. If you are caught up in the "green thing" and want to keep the air clean.. Vent the crank case into the air cleaner.. then at least you will be lubricateing the choke butterfly.. LOL.

hudsontech

The first Hudson I had, a 53 Hornet, had both valve covers with the down draft tubes. Seemed to work fine. Until I got to a Hudson meet I thought that was a normal installation. I suppose now, looking back over the years, the theory behind that type of installation was if you're going to vent half the valve gallery, why not vent both ends. Besides, it looked sort of cool under those twin-carbys.

Hudsonly,
Alex Burr
Memphis, TN

[Deleted User]

My brothers 54 Hornet had been modified to a pcv system by the previous owner when he rebuilt the engine. After a short while a skip developed and I found that all the exhaust valves were weak and & 6 was burned bad( took a triangle out of it). I believe it was due to the pcv system causing a lean condition. We did a valve job and elininated the pcv set up and have put a bunch of miles since with not troubles.

Tom

[Deleted User]

Your points are well taken that you need to be carfull an not second guess the original design of a motor. As I said I thought it would be a "Stop-Gap" fix for an oil burner/leaker. Perhaps it would be better to use a vacuume pump vented to the atmospher instead? An electric one or maybe the dual fuel pump top half ?
Roger

dougson

I installed a PCV valve when I assembled the engine. I simply cut the blow by tube near the valve cover and welded a cap on with a hole for the valve. My '56 engine has a second vacuum tapped in on the intake that serves as the positive side. I asked a lot of folks about this and did some research. The purpose of the "blow by" was that it was drafted to the outside below the engine in a position to trap passing air and vent the crankcase, however, idling and slow speed defeats the purpose and acids and gases can accumulate in the crankcase eventually building up deposits and crud that can become explosive and over time etch surfaces and neutralize the viscosity of oil. Remember the old days when you could detect a worn engine by the smoke that would pour out of the tube. Actually PCV wasn't simply a pollution control developement, it actually increased engine longevity and efficiency by allowing for a constant flow of fresh air through the engine and combustion of gases. I have an air monitoring gauge installed and have not noticed excessive lean mixture, even with a header. I've had the head off (again) and the (stainless) exhaust valves look fine. A lean condition can be addressed by advancing the spark a few degrees,

Ol racer

Dougson,
Very well said. All my Hudson Motors have ran well a number of Yrs using PCV Valves. If Hudson's were built today they would have all of todays modern technological advancements....
Hudson Engineering was great in that Period, perhaps best in Class, but remember, back then every corner Gas Station had a Mechanic with a Valve Grind Machine, and motors rarely lasted over 100,000 Miles weith the best of care.... There have been so many Automotive Engineering Advancements its impossible to List..

[Deleted User]

Wow! you guys are getting way to technical for me! I wouldnt put one in just to p--- off all my tree hugging friends. In fact I sometimes put several ounces of motor oil in my gas to lub. my valves. The more they complain the more I drive it. Hows that for being sinister?

[Deleted User]

Actualy you should put something like Marvel Mystry oil in your gas to keep the valves free and clean. And help with vapor loc to some extent by changing the flash point of the gas slightly,
Roger

Browniepetersen

I agree with you Roger. I buy gas locally that does not have ethonal (corn sugar) and then add lead additive and MMO. Seems to work for me.... By the way, anyone know how to use spell check on this site?

[Deleted User]

Where are you buying it Brownie? We were talking about this just the other day at Stockland's. But, nobody could remember where the station was.

Browniepetersen

There is a small business station (credit card only-no attendant) just north of 17th street across the street (on the east side) from the farmers store. The only Ethonal free pump is on the inside next to the fence. Price is less than the majors and more than Maverick and it is only in the 87 octane.