I believe Carl is correct. I have an engine that was in a 1946 and it has the oil fill at the top of the breather tube. I don't recall if that had an oil fill on the valve cover or not, but could check that.
[on edit] The valve cover on that engine had an oil fill cap - probably swapped out for a later valve cover. Here's a pic of the breather tube with the oil fill cap.
Last edited by klhansen; 10/03/20253:07 AM. Reason: added more info & picture
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
That valve cover was used on my '50 COE and probably on all the advance design COEs. The valve cover lies just beneath the "doghouse" so the only quick access to add oil is with the breather tube with cap. In fact my truck had a later 235 and the original cover was fitted to the engine for the very same reason. Kent
If I had a downdraft tube with an oil fill cap on it, I would put a breathe cap on it as an inlet for fresh air for a PVC set up which would draw the fumes out of the engine via a PCV valve in the valve cover. I would of course need to block off the lower end of the downdraft tube. I realize that this is backwards as to how the original PVC was setup for these engines, but I have always thought that the engineers had it backwards to begin with. To be fair to the engineers back in the day, there were very few paved roads back when these trucks were new, so the location of a breather cap on a downdraft tube would not be drawing much "fresh" air that close to the dirt roads.
Last edited by 52Carl; 10/03/202511:45 PM.
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
If I had a downdraft tube with an oil fill cap on it, I would put a breathe cap on it as an inlet for fresh air for a PVC set up which would draw the fumes out of the engine via a PCV valve in the valve cover. I would of course need to block off the lower end of the downdraft tube. I realize that this is backwards as to how the original PVC was setup for these engines, but I have always thought that the engineers had it backwards to begin with. To be fair to the engineers back in the day, there were very few paved roads back when these trucks were new, so the location of a breather cap on a downdraft tube would not be drawing much "fresh" air that close to the dirt roads.
I run mine kinda like that. Motorcycle-style breather clamped to bottom end of draft tube. PCV in the valve cover.
Re PCV: There is a early 60’s corvette v8 oil fill tube with takeoff that fits perfectly in the bottom of the Stovebolt, giving oil fill and PCV takeoff… Sorry for the dark pic but look closely it’s there…
