1946 VB (Iron Head )valve chest oiling

[garycullen]

I am a bit worried that not enough oil mist is getting up into the valve chest area.
It looks quite dry in there when I take off the finned cover.

Looking down into the well at the bottom between the valve tappets the hole where I presume oil mist should rise from looks very small to me.
Maybe 3/16" dia.
I have poked a bent wire into the hole and it goes right through and hits the cam or some part of it. so it is not blocked.

When the engine is idling I get puffs of warm air felt on my fingers coming out of the breather tube from behind the Magdyno time case but I can feel slight pulses of suction from the valve chest breather. This confuses me as the timing case interior is the same area as the valve chest interior atmospherically.
I rebuilt this engine with new Valves and Valve guides and the valves were hand lapped. I am sure the seating is good as I can't kick through the compression stroke with out the use of the valve lifter.

I recall the hole going through the Crank case to match the barrel hole into the valve chest is a lot bigger in diameter.
I am wondering if I need to take the barrel off and drill out the small valve chest hole to match the crank cases bit better.

Any

[nevhunter]

IF you drill it bigger you'll get shavings in the timing case. At least you will get no dust there. Put a tiny bit of oil in your petrol and forget it. Nev

[garycullen]

Thanks Nev.
I am unsure how a small drop or two of oil in the petrol tank will be of any benefit in the valve chest area.
Or even how it will get there. Valve seats and I guess some benefit in the guides but I am sceptical it will get down to the tappets. But I am happy to give it a try.
Can you comment on the small suction pulses I can feel from the valve chest breather?, but puffs from the timing case breather?
The timing case breather is a brass elbow with a ball and split pin inside it. The valve chest breather is just and open Banjo connection.
Cheers
Gary

[Simon.Gardiner]

Gary:
Valve chest is connected to timing chest I think?
Timing chest breather is one way ball valve lets air out (as puffs) but not in, so on 'up' stroke there is a depression/suction in crankcase/timing chest/valve chest, which will probably result in the suction pulses ?
(Get the engine runing slowly and check to see if the 'puffs' and suction pulses alternate! )

SG

[garycullen]

Simon, yes that is my understanding as well. But I thought that I would feel puffs and suck pulses from the valve chest breather.
I confirm only puffs from the timing case breather.
Maybe I am worrying about nothing but after I run the engine for maybe 5 minutes And then take off the finned valve chest cover while the engine is running I expected to see evidence of an oily mist emanating from the small hole in the bottom of the valve chest area…but no.
Nev’s recommendation of a couple of drops of oil in the petrol will lubricate the inlet valve stem and I guess some residual oil will be present in the exhaust gases to get to the exhaust valve stem but is it enough to get down through the guides to the tappets?
Gary

[Simon.Gardiner]

Ummm - what happens if you block/obstruct the timing chest breather?
(OK, you've probably done that already...)

From my one experience of a VB crankcase and barrel, that hole is pretty small (3/16 seems about right). However, I'm going back a very long way for this - aren't there also grooves/slots in the tappet blocks which also provide a path for oil mist to go 'up' ?
I've always assumed the hole you're referring to is a drain hole, although that might be me thinking with the 'OHV head' on. Is it possible your tappet blocks are gummed up?
(Or maybe I'm barking up totally the wrong tree, my VB experience is a very long time ago...)

SG

[garycullen]

I haven’t tried that Simon, but great idea and I will do so next time I start her up, ( I have difficulty getting her to start reliably which I am sure is carb related. I am working on this separately.)
I also have another part engine with all the valve gear and I can check those tappet blocks for grooves.
I can’t recall seeing any when I cleaned up the engine parts I have used…..
Gary

[garycullen]

My take on the hole is that it is both a drain and an oil mist hole.
Gary

[nevhunter]

Side valve tappets don't wear much. It's all a straight push. No dust will get in there but some gas will come down the exhaust guide. You can squirt some oil in there occasionally if that makes you feel better.It will end up in the cam case. Breathers always have puffs at low rpm. It CAN allow dust to get into the engine. A One way flap/ball valve stops that. Nev

[Simon.Gardiner]

Grooved tappet blocks - pretty certain I'm talking nonsense there, getting mixed up with memories of AJS/Matchless singles tappets.
Sorry about that - I did say it was a long time ago....

There must be some regular VB riders around who can shed some real light on this!

SG