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Dave

On reviewing what I have posted I realise a point of clarification is needed regarding engine breathing.

A couple of photos show a breather fitting in the rocker box. I did not use this so plugged the existing hole.

I didn't want air rushing up the pushrod tubes and oil drain gallery which I felt would interfere with their oil drain function.

The last photo in my previous post shows the two breather hoses with reed valves (Ken McIntosh - NZ). The rear one used to have a pipe dripping oil on the drive chain.

The front one is new - I figured I wanted you tap into an area of still air (difficult on a crankcase) as Bernoulli's law predicts lower static pressure when the air has velocity.

The photo below shows an unused chamber above and in front of the crankshaft (upper RH in photo). I drilled a 3/8" hole from the inside into this chamber in the RH casting.

Then drilled and tapped a BSPT fitting on the outside on the LH casting (can be seen in photo). Seems to work well.

Also plugged the timed breather hole in the LH crankshaft (outside main bearings) to prevent oil getting into the primary case

Cheers

rob