I have a crank to have ground what is largest I can get I'm only seeing .030 in but I need .040 in to cleanup the crank I have.
It depends on what the largest oversize bearings available are. If .030" is the largest you'll need a new crank but maybe the crank can be spray welded and reground to the size you need.
.030 is normally it--reason grinding a crank below .030 removes to much in the area of the journal radius which weakens the crank. Welded cranks can work but it really depends on procedure followed, I personally prefer not to use a welded crank shaft.
If its only one journal that’s bad, a proper welding job and regrinding ‘may’ be an option depending on the availability of a better crank. I would make sure the shop specializes in crank buildup and if they have any experience with the old Deutz cranks in particular. If i remember correctly, Deutz had some specific regrinding and polishing procedures to follow that some shops may not be aware of. Also, maybe the crank will have to be re-nitrided after regrinding to .030 undersize because the nitrided layer is not very thick and may be gone after the .030 grind
Would be surprised if nitride, under the stress I would think forged.
Forged ya, but with the older Deutz engines i’m not sure about what their complete crank manufacturing process was. At one time i think they were worried about ‘fish scaling’ during grinding. Those old Deutz air cooled engines rarely had crankshaft problems. Most were caused by running out of oil or repeated severe overheating. At least the ones that I encountered
Honda was the one that was hot on nitride cranks all the way back into 70's.