Unusual aluminum valve cover for TC

[bimmrr]

The coffin style valve cover on my 1948 TC has a breather hole on top with a "plug" on it that appears to allow the valve cover to breathe ? Question, the standard round air cleaner canister currently has a separate piece of rubber tubing attached to it. I have attached a picture where you can see the rubber tubing and the vertical breather pipe on the top of the cover with the "cap on it" ( white arrows) Should I consider running the rubber tubing directly to that vertical pipe or just remove the tubing entirely ?
Thanks,
Mike

[Steve Simmons]

That valve cover appears to be an Arnolt, but the breather connection is on the wrong side. EDIT: I just realized that's a TD Arnolt cover.

Ordinarily the two ports (on filter can and valve cover) would line up. I can't tell where the rubber hose is attached now, but it should be into that breather port on the valve cover as a way to get the two of them to connect despite the misalignment. I don't see a problem with this other than being a bit unsightly compared to original.

Here is the correct configuration on an Arnolt cover made for TC...

[bimmrr]

Hey Steve,
Thanks for the reply. The current rubber hose actually does not connect to anything, just hangs over the edge of the valve cover. Obviously not correct in function or appearance. Going to see if the small breather "pipe" with its cap allows for the cap to be removed and if the rubber tubing ( heater hose of some kind) will connect more directly.
Regards,
Mike

[Rob Reilly]

That appears to be an early form of positive crankcase ventilation, a low pressure sucking of crankcase fumes into the air filter and being re-burned. Here it is on a 1950 Jaguar, same idea.

With it connected you will notice less crankcase unburned fuel smell around the engine when running.
All cars began to have PCV in the 1960s and we are hardly aware of it anymore in our modern cars.

[Duncan M]

Rob-
But it is not Positive Crankcase Ventilation (PCV) because there is no fresh air ventilation being pumped in. At best, it is an improvement on the plain old draft tube. The oil change intervals we are used to in modern cars are because the PCV systems make the oil last much longer-- before it becomes polluted and acidic and sludgy. Crankcase gasses are very acidic. With no PVC, like in our TC's, the oil goes bad (acidic and sludgy) much sooner. Cars with these primitive crankcase pressure venting systems need to have the oil changed much more often than a car with an actual crossflow PCV system.

I am in the habit of not going more than 1000 miles between oil changes. Even then, if you look closely at the drained oil and see what sort of looks like black spiderwebs mixed in the drain oil, sort of floating around in the drain pan, that is the early stages of sludge formation.

[bimmrr]

Here are a couple of pictures I took this morning which better show what I have with this valve cover and vent tubing/hose from the air cleaner canister. The vertical "post" has the small cap on it and someone has stuck in a bit of fine steel wool as a simple filter. And as you can see, the air cleaner canister has the tubing attached and it simply sits on top of the valve cover.

[Steve Simmons]

Now that I think about it, TD had a tall breather pipe on opposite side as TC. So your valve cover must be a TD version. Other than the vent location and shape, the cover appears identical to the TC version.

[bimmrr]

That makes sense ! Now to just get a TC valve cover, anyone have a spare out there ???

[Steve Simmons]

If it doesn't have to be an Arnolt, there are more common covers available. Bell ribbed covers aren't too hard to find, and the original style MG alloy covers can be bought new from most retailers. If you want an Arnolt, they are a bit scarce, especially the TC version. Maybe there's a TD owner out there with a TC cover who would trade.

[Rob Reilly]

Duncan,
If the hose on the air filter was connected to the stub on the valve cover so crankcase fumes can be sucked into the carbs, and there is a draft tube on the side of the block where air can enter, then that would be positive crankcase ventilation. Positive in this sense means it is intentional air flow, not just by the road drafts.
That is what the Jaguar has.
I remember my dad had a Studebaker where the only vent was a screen in the oil filler cap. It made quite a mess.

[antijam]

.......... and the original style MG alloy covers can be bought new from most retailers.

I did actually buy one of the repro 'original' style covers but was very unimpressed with the quality so sent it back. Some time later a genuine pre-war (TB) cover came up on eBay. I'm not sure anyone realised exactly what it was so I got it very cheaply and after a bit of elbow grease it came up well.....

It is of course anachronistic on my '48 car, but since the car is hardly original in many other respects I'm not too worried - and I like the look.