Forgive me if I haven't found the right keywords and this is already answered elsewhere...

I have a blackened (so presumably once fitted) Speedex valve chest cover which has not been drilled to allow venting. To save making holes in it I was considering allowing the crank case to vent through the blanking plate that will be needed over the hole where the soon to be redundant fuel pump sat.

My question is - does the lubrication of the valves require the flow of air that vents through the valve chest cover to bring oil mist up through the perforated top hats, is there another route that I have stupidly overlooked, or does sufficient oil get there anyway to allow venting elsewhere?

Regards
Nick

Location: Essex

Thanks for the Email. as I thought, I will get my drill out!

Location: not in the garage :(

Might sound like a daft question, but here goes. How much lubrication do the valves get. The reason I ask is having found that I had a water leak in the valve chest area I have replaced the block. On refitting the valve chest cover, early type full cork gasket, there is no sign of oil. The engine had done some 1200 miles.
There was rust on the inside of the cover indicating no oil, or was the water steam cleaning it ?.
If the oil mist that comes up the ventilated top hats is the only form of lubrication how is a airflow imparted as there is no exit unless it gets sucked up the valve stems ???

Location: Oakley , hants

Fifty years ago I was advised to get rid of the Welsh Hats. Or Top Hats if you prefer.I have to admit that I can't remember why. The advice came from a reliable source however. Must help with breathing, lubrication, draining or nothing at all!

Location: Wales

Hi Derek,

From memory (poor at the best of times) I think the full cork gasket has two extra holes which allow air to pass through and out of the vents in the tappet chest cover.

Location: hiding in the kitchen (last place they're going to look! )

Yes , they are only 12mm diameter , Derr never thought of those. Still doesn't explain the clean cork though

Location: Oakley , hants

Possibly the 'top hat' valve chest breather filters were blocked in the original set up.

Cheers, Tony.

Location: Melbourne. Victoria, Australia.

I suspect that the top hats are blocked Derek, all mine valve chest cover joint are covered in oil. Leaving the top hats out isn't a good idea the vacant holes seem to have a magnetic attraction for valve collets.

It's not blocked Top Hats. I have replaced the block but using the same top hats I checked them and were clean so have used them again. The mystery goes on.
Thanks for your help chaps

Location: Oakley , hants

Thinking back to my first Ruby, when the piston rings broke up (due to rusty ridges following a 10 year lay up in a damp shed by the P.O.) she blew smoke rings out by the starting handle. I wish I had thought to video them!

In your case Derek I would think it is possible that steam filling the tappet chest could have stopped the flow of air through the top hats and the oil mist that would have lubricated the valves may have exited your engine via the nose too.

I have not tried steam cleaners... but...

I thought I had a lot of oil leaking from my tappet chest recently, then remembered something about the square headed bolt into the front cam bush... oh joy

Location: not in the garage :(

Thanks Nick,
You may well be right. Have now done four miles on the new engine but am loathed to disturb the valve chest cover to have a look.

Location: Oakley , hants

I strongly suspect that oil mist will not get into the valve chest if there are no ventilation holes on the cover. If there is no outlet then the valve chest will just be at the same pressure as the crankcase so there will be no incentive for it to flow into the valves.
The same thing happens I believe with the rear main bearing on 1-1/8" cranks. There is no outlet on the gearbox side of the bearing so no incentive for oil to find its way through the bearing.
The inside of a splash lubricated engine must be a very oily place indeed. The oil from the jets hitting the fast moving crank will create a great deal of oil mist. The main reason why the engines leak oil at the slightest excuse.

Location: not in the garage :(

Good idea

Location: Oakley , hants