Tappet Cover oil leaks

[Charles P]

As part of my ongoing quest to create an oil tight engine I'm looking at the tappet chest.
On my car, because of the blower, I have a tappet chest cover made from 10mm thick aluminium plate (I'd have to remove the blower to get to the tappers with a standard cover). Since everything is in bits I was contemplating machining an O ring groove into the plate to give a better seal. However my replacement 1929 block is the early type that has virtually no register at the top for any gasket (O ring, cork or paper) to push against. (See picture below)
What has anyone else done to help make this leak free? I have thought about machining a groove in the face for the bottom and sides and in the top of the 10mm plate for the top seal. Mad?

   

Thanks 

Charles

[Speedex750]

Hi Charles,
I can understand your intent to 'do it once, do it right' so you don't have to take the blower off. Looking at the picture of your block, and my similar broken one - there is a slight register plus a land at 90 degrees above it. I'd ensure the register is flat all round and stick the cover on with no gasket only Loctite 515 or 518 including getting a seal on the top edge with the underside of the ports?

Another aspect of this is to minimise crankcase pressurisation with a good breather. I've heard big Yanky V8's sometimes use a vent into the exhaust to pull a negative crankcase that reduces windage losses. But it sounds a bit of a stretch for me and I suspect the 'spit and hope' lubrication may well spit the whole lot out down the exhaust very quickly!

Dave

[Zetomagneto]

As part of my ongoing quest to create an oil tight engine I'm looking at the tappet chest.
On my car, because of the blower, I have a tappet chest cover made from 10mm thick aluminium plate (I'd have to remove the blower to get to the tappers with a standard cover). Since everything is in bits I was contemplating machining an O ring groove into the plate to give a better seal. However my replacement 1929 block is the early type that has virtually no register at the top for any gasket (O ring, cork or paper) to push against. (See picture below)
What has anyone else done to help make this leak free? I have thought about machining a groove in the face for the bottom and sides and in the top of the 10mm plate for the top seal. Mad?



Thanks 

Charles the Oxfordshire sevens cover has a rubber seal http://www.oxfordshiresevens.co.uk/parts...sis-parts/

Most of any leakage would be along the bottom? Not much you can do about lack of register along the top edge

[Hedd Jones]

Could you put the block in the mill and take another 1/16 or an 1/8 off the bottom of the lump under the manifold?

[Austin in the Shed]

I would set up the block and machine the face another 1/16" or so up and make sure the cover goes right to the top and seal with Loctite or similar.

[Chris KC]

Personally I wouldn't go machining grooves in a perfectly good 1929 block. 
I agree with Dave that ventilation might be a good idea, if it's pressurising then an o-ring will not stop oil escaping.
A nice stiff, flat cover and a modern hi-temp sealant (following the instructions!) ought to take care of the rest.
And yes, a flange / seal on the fixing studs so it doesn't come out of the stud holes.

[Charles P]

Looking at this again last night the idea of cleaning up another 1/16 at the top looks the smart option.

The O ring groove was going into the cover plate, not the block. I might machine the extra land and check the fit with blue before sealing with loctite.

I find it difficult to believe that pressure will be a problem when the timing chest vents to the crankcase and the crankcase is vented through the oil filler into a catch tank. 

Charles

[Nick Lettington]

Charles

Dont you think it better to alliw venting through the tappet chest cover? How else will the oil mist lubricate the valves? Or do you have a clever modification?

[Alan]

Valve stem lubrication has never been a problem for me and I've been using engines vented from the oil filler pipe for 30 years or more. You need a big vent pipe. The race engine has 3/4 in dia.
It probably won't help you here but I use a Reliant SV tappet chest cover. These are a cast Ali version of the Austin pressed steel job. They have a groove to take the cork strip seal, but I use O ring cord. No leaks.

[Tod]

Hi Charles,

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Hi Charles,
I replaced my tappet cover using a piece of Alumimium Plate 6mm thick. I drilled 4 x 3/16" vent holes quite near to the top at 45*. I machined a light channel up from the bottom edge to ensure that the plate was not held off by the Cylinder Fixing Nuts. To seal it I simply used a smear of Loctite SI 5980 instant gasket, but I suppose any good sealant of this type would do. I secured the plate using 2 bolts with plain and Fibre washers and to date I have had no leaks.