Hi Mark
Nice pic! These digital camera’s are a real boon when you want to convey this sort of info.
LH lock nuts
I never use them.
If you knock up the crank properly, you will never need it.
My new cranks use a cap screw and no locknut.
I am sure you have researched the subject of crank assembly, but in case you fancy a refresher, click the link–
https://www.mossengineering.co.uk/index.php?area=5&content=96
As regards air leaks
1) If the seating face for the door has been broken where it is thin at the rod loading position, this can be a problem.
2) Be sure there are no air leaks from transfer port gaskets.
I have known them to break where you cannot see and leak air badly. The alignment of the transfer port seating faces on the block and case are often not in good alignment and so do not grip the gasket properly, hence them breaking.
I do not use gaskets. I just degrease and seal with RTV silicone, usual K mart stuff you use round baths.
I use the same to seal barrels into crankcases. In fact, to be honest– I do not usually use any Scott gaskets in my engines. And– they still work!!!!
Stans idea to spray petrol is good and should pin point the position of the problem.
However
One extra tip–
Do not smoke while you do it!
Kind Regards
Roger
