Camshaft centre bearing in 3 to 2 bearing crankcase conversion

[dchw1975]

Hi,

I have recently purchased a crankcase that has had a conversion which removes the centre bearing and enables the fitment of a 2 - bearing crankshaft. My question is about how the plain centre bearing on the camshaft is lubricated now that the pressure feed to the centre main bearing is removed or whether you have to move over to a 2 bearing camshaft as well?

The conversion appears to have been done very professionally it's just I don't understand this one bit of the 'puzzle'...

Regards

David

[Ruairidh Dunford]

There should be a hole drilled through the top of the crankcase and into the centre cam bush, you need to make sure the block you use has a corresponding hole drilled into the block above this.

Oil travels down through the hole from the valve chest area.

[dchw1975]

Thanks, so that bearing can survive well enough without a pressure oil feed? slightly surprising but good. I assume I also have to drill a hole in the top of the bush as well to allow the oil to get into there?

Regards

David

[Chris KC]

Indeed you do David.

I can vouch for the fact that the supply is quite sufficient. I suggest a hole dia 3/16".

[Robert Leigh]

The crankcase which was converted for me has diagonal grooves in the bearing halves, so that the oil reaching the grooves by splash will spread across the bearing. May I suggest that a combination of both methods may be a good answer.