Early PCV valve on model t
Posted: Sat May 04, 2024 10:32 pm
Saw this on a fbook marketplace T truck for sale. Interesting homemade setup. But wonder why.
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Re: Early PCV valve on model t
Posted: Sat May 04, 2024 10:51 pm
Not "home-made" - actual era accessory !
Re: Early PCV valve on model t
Posted: Sat May 04, 2024 11:06 pm
Must have been a California T! 
Re: Early PCV valve on model t
Posted: Sun May 05, 2024 12:07 am
I ran a PCV on my speedster for years until recently… if you can seal up the crankcase it works wonders at controlling oil leaks!
Re: Early PCV valve on model t
Posted: Sun May 05, 2024 8:21 am
What was the downside to using the PCV setup? I would think plug fouling and combustion chamber build up.Kevin Pharis wrote: ↑Sun May 05, 2024 12:07 amI ran a PCV on my speedster for years until recently… if you can seal up the crankcase it works wonders at controlling oil leaks!
Re: Early PCV valve on model t
Posted: Sun May 05, 2024 10:29 am
No downside, other than non-originality.
Using a positive crankcase vent arrangement can reduce oil leakage and prevent water and gasoline condensate in the crankcase. Oil mist escaping the oil filler will be reduced, leading to a cleaner engine bay. The oil mist will actually tend to reduce ring and valve stem wear. It will not cause any issues unless your rings are totally worn out, and it probably wouldn't then. The device in the picture appears to be a combination positive crankcase vent and intake air pre heater.
A modern type PCV connected to the intake manifold above the carburetor would do a better job. I don't know if the T carburetor would need to be modified to use one, but I don't think it would
Keep in mind that a positive system will pull more air than normal through the crank case, which is all to the good, but the air needs to be kept dust free by some means. With an older T, air would be drawn in where the throttle rod passes thorough the engine. On the late models, it would be advantageous to provide an air inlet by modifying the valve chamber cover or using an older model one with a hole in it.
Using a positive crankcase vent arrangement can reduce oil leakage and prevent water and gasoline condensate in the crankcase. Oil mist escaping the oil filler will be reduced, leading to a cleaner engine bay. The oil mist will actually tend to reduce ring and valve stem wear. It will not cause any issues unless your rings are totally worn out, and it probably wouldn't then. The device in the picture appears to be a combination positive crankcase vent and intake air pre heater.
A modern type PCV connected to the intake manifold above the carburetor would do a better job. I don't know if the T carburetor would need to be modified to use one, but I don't think it would
Keep in mind that a positive system will pull more air than normal through the crank case, which is all to the good, but the air needs to be kept dust free by some means. With an older T, air would be drawn in where the throttle rod passes thorough the engine. On the late models, it would be advantageous to provide an air inlet by modifying the valve chamber cover or using an older model one with a hole in it.
Re: Early PCV valve on model t
Posted: Sun May 05, 2024 2:12 pm
The late RDR Ralph Ricks had a PCV valve connected from the filler neck to the intake manifold on his PCup Great Race car. I was hardly noticeable and did have the Cal Smog approval I'm sure!