Halfway through undertaking a helicoil thread repair on the vave chest side of the top of my crankcase, somewhat belatedly, I decided to put on my glasses and then saw that there are hairline cracks radiating from two of the threaded stud holes to the adjacent holes in the top of the crankcase that accomodate the cam follower guides.
My gut feeling is that these radiating fractures are likely to be terminal but before I consign the crankcase to the metal recycler I'd appreciate the forum's view.
The cracks look to be around the centre of the case? In which case they are close to the centre cam bearing. If the case is special to you (ie matching numbers) then the area could possibly be welded but would then require that centre cam bearing to be line bored. Probably not worth it for a run of the mill case.
Possinbly caused by gasket too thick/soft.Those giant threads are not going to pul out.The crack of concern would be the one above the cam bearing. i had a crankcase cracked at the middle arch and welded eons ago but a lot of distortion and the cam tunnels never aligned properly.The ingenious may be able to devise ways of supporting the cam bore other than welding..
Bob, Howard & Bob
Thanks for your thoughts on this. You are correct that the the cracks are close to centre camshaft bearing. The crankcase is not a special number so I shall seek out another, not so easy whilst auto jumbles are not happening.
On the internet crankcases, like human beings, are not necessarily quite as they appear.
Rory
Tony
You are correct the cracks are in the crankcase, not the block
Leaf
This is for my 1936 Nippy. Its original crankcase demised sometime before 1972. I'm aware that Nippy crankcases have been likened to dentition in egg-producing domestic fowls, so I will be compromising by seeking out a rubber mounted high frame case.
Rory
