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Valve Cover Vent Pipe

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CaptRoy

Jedi Hopeful
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I bought a valve cover for the new engine and it does not have a vent pipe. My old cap won't fit it as the new valve cover has one of the twist on caps.

Is this ok? I have the breather on the engine. It was suggested to me that a breather on the valve cover was necessary and the TR3 cap provided it.

What do you guys think?
 
I'm not sure if it's needed, but just to be safe, can you drill a couple of small holes in the underside of the new cap - somewhere inconspicuous? Would relieve any pressure buildup that might occur.

Mickey
 
I think that "suggestion" to you might be correct. There are any number of variations of the basic wet-liner motor valve cover.

The ones with the twist-on caps (to the rear of the motor usually, as well as earlier TR4 push-on caps; most TR2-3 models had the breather-style cap up front) would be for the "closed" systems with a single separate pipe from the valve cover to the intake manifold (possibly a PCV valve) or carburetors. Valve covers with push-on breather-style oil caps would not have had any other pipe, although you'll find some TR3B and early TR4 variants with a brass plug in the middle of the cover (presumably to accommodate early closed-crankcase vent systems in some way?).

BTW, one of my cars happenes to be TS71909L, built 3/28/60, probably less than a week after yours, Roy? My other one, TS73624L, was built 4/15/60. They were still crankin' them out pretty quick in early 1960...until the bottom fell out of their markets.
 
It has been nearly 40 years but on my TR4 I seem to remember a crankcase breather from the side of the block behind the fuel pump. Nothing fancy, just a pipe (and a place for oil dripping from the engine).

I do not remember the if or how the valve cover might have been vented.
 
I think the vent pipe came in with the TR4 engine so on a 3 it would have to be a 3B or later [original] engine.

Before that the TR3-3A had a breather element on top of the valve cover and the road draft tube on the block behind the fuel pump.

TR4 engines had the tube from the vaive cover connected to a flame trap between the carbs.

On the TR4A, the tube connects to the PCV and puls vacuum from a port on the intake manifold.

Also during all these valve cover changes, the filler hole moved from front to back and used a closed oi cap instead of a breather.
 
[ QUOTE ]
...TS73624L, was built 4/15/60. They were still crankin' them out pretty quick in early 1960...

[/ QUOTE ]

I guess they were. 4/15/60 is one year to the day after TS47905L was built.

As for valve covers, I'm under the impression that --

TR2/2/3A: Push on cap towards front of cover, no vent in cover other than cap

TR3B/Early TR4: Same as above except the cap moved to the rear of the valve cover. Cover has brass plug Andy mentions.

Late TR4: Cap is sealed (looks a lot like a radiator cap except it has names of oils on it). Cap is still at rear of cover. Cover is vented via a fitting on the carb side that connects hose-pipe-hose-flametrap Y piece-pair of hoses to the carbs. Fairly ineffective at venting the engine IMO.

The road draft tube was on the side of the block (near the fuel pump) on cars with the vented cap. No tube (hole is plugged with a sheet metal plug) on cars with the sealed cap.

I added the road draft tube to my TR4 with a sealed cap. Prior to that it wanted to push oil out of every seal... just couldn't vent effectively thru that carb connection. Now it's fine and I do not get significant oil out of the draft tube.
 
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