Wanting to dress up a Cadillac 390. The aluminum valley pan has no provisions for a down draft tube. I'm debating to install it or a PCV valve. What about valve cover breathers instead? Like to have one on each side mounted on the sides of the Offenhauser covers. What say y'all? Like something traditional. It'll be a rebuilt engine. Anyone do a PCV valve conversion on one?
Well, from an engine protection standpoint, the PCV is far superior compared to the other two options. That being said, you could use the valve cover breathers with a PCV system. Two options. First option, both breathers as air inlets and install the PCV valve in the valley pan. Second option, use one breather as the air inlet and modify the other breather and hide the PCV valve in the other breather. Both will require a line from the PCV valve to the intake manifold or carb base.
The breathers let air in while your PCV or Road draft tube is scavenging the crank case. breathers alone will not do the job. You just have to decide which you want to run road draft tube or PCV valve. The PCV is superior the road draft tube will do almost nothing at low speed.
I'd drill the aluminum valley pan, and either install the stock road draft tube back in it or try a pcv valve in it. I think the caddy valve covers are way to pretty to put breathers on.
The reason all the OEMs went to locating the PCV and oil fills in the valve covers was to insure full air changes inside the motor. Using the valley pan/intake prevents this and promotes condensation in the valve covers, leading to sludge build-up. This is more true in high-humidity areas.
Have vintage Offenhauser valve covers (no PCV ports). I came off my p***enger side breather with an inline PCV to the carb base. I used a breather screen as a template and cut a plate from sheet metal to plug the top of the breather and epoxied any voids around the edges to seal it off. I then stuffed the breather full with a stainless pot scrubber for a filter. The driver's side breather is unaltered so it's pulling across the engine, grabbing the crankcase pressure.
AC Delco 19310783 or Standard Motor Products 112V which should be the same valve. Has 1/2" inlet and 5/16" outlet.
OEM's stopped making engines with valley pans long before they went to PCV. Sent from my SM-G973U using The H.A.M.B. mobile app
Well, the PCV valve first showed up in '62. Ford built the Y-block until '64, AMC V8 though '65, Buick built the Nailhead V8 until '66, Pontiac V8 until at least '73, and Chrysler until '78 (B, RB motors). All used valley pans.
The PCV valve has been with us since the 1930's. They were known as "Donaldson Valves", and used on virtually all HD truck, bus, & industrial engines.
“I’m the Dude, so that’s what you call me. That or, uh, His Dudeness, or uh, Duder, or El Duderino, if you’re not into the whole brevity thing.”
Old front motor fuel cars just had breathers and that's what I have on my old hemi and they seem to work fine...
The Jalopy Journal
