Opinion on PCV valve for flathead?

B

BobM

Senior Member
Any thoughts on the value of running a PCV valve on a flathead? If I change oil every thousand miles is there any benefit in running one?
 
Don't know if there are any noticeable benefits but it sure gets rid of the flathead blowby smell coming out of the breather and road draft tube:)
 
51 MERC-CT said:
Don't know if there are any noticeable benefits but it sure gets rid of the flathead blowby smell coming out of the breather and road draft tube:)
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Which PCV valve did you use, I think I saw where a PCV valve from a Jeep would fit into the '49-'53 intake?
 
Bruce has been nice enough to point out the merits of a PCV many times on this forum and the HAMB. If I have it correct, the military flatheads had them and the biggest benefit of having one is burning off the moisture in the oil and that keeps sludge from forming. I have one on my 8BA from the gent who sells the neat kit to do this on E-bay. Right now I have a Southwind heater vacuum plate under my carb that provides the suction. However, my plan is to run the tube from the PCV to the air cleaner and vent the crank case that way. I think that will allow me to keep my manifold vacuum higher and use it for the distributor vacuum source.
 
the problem with running the pcv to the air cleaner is that there is not enough vacuum or suction to make it work at idle, off the carb or manifold it works good at an idle and is restricted when at hi way speeds, the one to the air cleaner works good at hiway speeds due to the extra suction by higher engine rpm's
 
PCV valve in proper form goes into intake manifold vaccuum, I picked out a pcv valve by finding one that is original to another engine about the same displacement, with the end I want to plump to (1/4" pipe thread) The air cleaner is the source for air into the crankcase... I could look to see what it was if anyone is interested... Karl
 
I have found that the Borg Warner #382 PCV valve and a Ford OHV grommett for a PCV valve are the best combination in an 8Ba intake manifold. The specs are;
Closed at idle 16-18 in Hg (Inches of Mercury(Hg) vacuam)
Floats at 8-10 in Hg
Open at 1-6 in Hg
 
Hi all; I put a PVC on my 59 A by welding up the oilpan vent and using a threaded [pipe] fitting there, then a hose to a carb base vaccum plate. No more seal leaks and the breather worked great, really cleaned up the engine. Newc
 
the air cleaner does not put air into the crank case, it pulls air out of there to remove fumes, the road draft tube allows air into the crank case to vent it if its still hooked up, if not you need a ventilated oil cap to let air into the crankcase
 
The crankcase air left the engine by way of the road draft tube. Air entered through the ventilated oil fill cap. As far as the need for it, I don't happen to have one on mine and after 17 years of use and around 50,000 miles there is absolutely not even a hint of any sludge formation. I'm sure it's due to the vastly superior oils we have today.
 
flatjack, your right, thats the way the originals worked, and it let the fumes out under the car at idle, but when you hook up a pcv with the original draft tube the air is pulled in thru it, the best way is to plug the vent tube and use a pcv valve off the carb or manifold with a vented oil cap, modern engines use 2, one for each valve cover, one from the manifold and one coming from the air cleaner and using a vented oil cap
 
A couple things to consider . If you have a motor that is meant to have a drain pipe in the rear main and you don't have one or if it is not long enough to stay immeresed in oil at all times you will be sucking all that wonderful clutch debris and whatever else is getting into the bellhousing cavity INTO your motor . And if you have this going on and also have a vented pan you will get all the dust and road crap into your motor . The main thing to remember is if you run a PCV you need to let filtered air into your motor. Many ways of doing this and yes you're talking about later motors but the principal is the same - you will be sucking debris into your motor . There isn't any harm in a PCV setup just make sure you filter the air going in . My 3.14 cents worth . David J
 
David is right on. I would not want to be drawing air into the engine from the road draft tube. Draw it from the air cleaner.
 
36tbird>>>my plan is to run the tube from the PCV to the air cleaner and vent the crank case>>>

ford1>>>the problem with running the pcv to the air cleaner is that there is not enough vacuum>>>the one to the air cleaner works good at hiway speeds due to the extra suction by higher engine rpm's>>>

As Lou knows, I'm running a simple reverse-flow no-valve PCV. A tube filled with stainless steel mesh runs from the air-cleaner cannister to the oil-filler stand. A fine air filter screen is also wrapped several times around the crankcase vent to prevent road debris from entering the crankcase. The main purpose of the mesh-filled tube is to prevent backfires as well as catch entrained oil droplets. Lou says he's found a PCV valve that works on low air-cleaner vacuum that should also serve a similar purpose.

Jack E/NJ
 
here is another advantage of a PCV on an early 24 stud motor, My 99A has a labrinthe rear main (no rope) and without the PCV would always drip oil due to being forced out by positive crancase pressure, which the vacuum PCV system reduces to a point where I dont get an oil patch when I park. I concur that,with the improvement in oil formulation and changing it regularly, sludge build up shouldnt be an issue.
 
I am running an 8BA w/ an early Eddie Meyer intake. I capped off the road draft tube w/ an elbow fitting and then drilled a hole into the center runners of the intake and installed a threaded PCV valve. It really cut down on the blow by, and it is hidden.

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Could be wrong but it looks to me like all you are doing is sucking in (with what little vacuum is available at the air cleaner) primarily fresh air.
 

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