The Stovebolt Site Forums The Shop Area Engine Shop Valve cover

Hey Guy's,
The rebuild on my 52 1/2t.is coming along nicley. I'm going to paint the engine today. While cleaning up the valve cover I noticed 3 factory made slots in the top of the cover. I had never noticed this before. Do any of your 216/235s have this? I showed it to a mechcanic friend of mine. He said he had never seen this before.Seems to me I would get oil over the top of the valve cover. My engine is a 51, 235.

GEC52,

What you have is the stock valve cover that had "breathing slots" in the valve cover. These slots and the block draft tube allowed water vapor and other vapors to exit the engine (and prevented build-up of "air" pressure inside the engine. The oil filler cap on these engines were not vented. A side benefit of these slots was that oil could also exit the engine and then coat the valve cover and other engine compartment metal parts, thus acting as a rust deterent :rolleyes: .

Valve covers with slots were used on 216 and 235 engines up to at least 1954.

In case your are interested, pre-'54 valve covers on trucks engines had 2 hold-down bolts in the top. '54 and later valve covers had 4 hold-down machine screws on the side. I do not know what year the 235/261 truck engine valve covers stopped having the breathing slots (my 1960 261 has no slots).

Tim

I'm not sure what year the slots went away either, but my 55 235 does not have the slots.

I had a '49 and '50 216 in my garage for a while and neither one of them had slots, just a breather cap.

My 55.1 has the slots, but not for long.
-Scott

Tim did not mention another "benefit" of the air breather slots, which is that if you are parked on a hill or an angle, and the cowl vent drain hose drips onto the cover, you can have water in the engine! Sometimes I have seen these hoses broken off so that water will get inside even if the truck is level.
Your enigne does have to breathe. That is why I have converted to pcv on some of my trucks, as an alternative to the vented cap. The vented cap has been known to rust out, and I have seen some that were like a pepper shaker spewing rust from the mesh into the rockers. You may find a better quality one with stainless mesh. Logic would have one think they would be made. Wartime (WW2) trucks had a miniature oil bath breather for the rocker cover on the splash 235's equiped with pcv.

How do you explain the stock Chevy non-slotted covers on my engines, which had no PCV, then, Ralphy? They definately had breather caps, and road draft tubes, too.

The 1955 Truck Shop Manual describes the non-vented valve cover with a vented filler cap. This seems to be the first year these were used on light-duty truck 235s.

All three of my 1954, 235 engines (1/2 ton manual, 1 ton manual, and 1/2 ton HydraMatic) have the 4 venting slots, the Chevrolet script along the top, and 4 machine screws to hold them to the head.

The 1954 Truck Shop Manual describes the use of 4 hold-down machine scews/bolts; and, the 1954 Engineering Features book/manual shows this new-style valve cover, with Chevrolet script, 4 hold-down bolt/screws, four breathing slots, and the older unvented oil-filler cap.

I do not know if this type of discussion is better than discussing politics - yes, I think it is.

Tim

4ontheFloor,

If you are referring to non-slotted valve covers with 4 hold-down scews/bolts, they could be 1955 or newer heads and/or valve covers on a non-PVC engine.

The 1960 261 (non-PVC equipped) had a road-draft tube, a non-slotted valve cover, and a vented oil filler cap.

What size and year are your engines (blocks and heads)?

Tim

Ralphy, I am very sure there were no slots in either of my valve covers, since I was the one that stripped them to bare metal, degrunged the inside, and painted them. They were the 216 style with the acorn nuts holding them down on the top. The filler cap was at the front end toward the radiator. I no longer have them, or I would post a picture. The truck had a 1948 head with smaller spark plug holes for some reason, but the other engine had the original head and both blocks were 1949/50 casting numbers.

Being that I live in the Pacific Northwest where a lot of rain happens, maybe someone swapped them for non-slotted covers at some time or another, but I know that my truck came from an Iowa farm and was not messed with in the short time it spent in Oregon before I got it.

I have seen so many pictures of differant valve covers on differant year vehicles that I almost think it depended which plant made the vehicle on what cover it recieved.

The 1958 235 and the 1962 261 I have both have the same Chevrolet script 4-bolt cover with no slots and vented filler on the front.