Offset grinding crank ?
 

In general, what's the guideline for finished journal sizes on a .013 stroked stocker crank?

Can one that's .010 and not stroked finish at .020?

Thanks! -Al

Re: Offset grinding crank ?
 

It all depends on a few things. Is the stroke on long side or short side of spec. How close is the index, 90*, 90*, 90*, 90*. The size of crankpin. We have made a +.013 crank and it be 10/10.

Re: Offset grinding crank ?
 

No, one that's already .010 would finish at .030. You can't take .013 off one side of the throw when there's only .010 to offset grind with.

Re: Offset grinding crank ?
 

Aren't you only taking .0065" off one side?

Re: Offset grinding crank ?
 

I savvy math but we're talking .0065 per side. ;)

Re: Offset grinding crank ?
 

If you take .010 off ONE side, you've moved the centerline .005, increasing the stroke by .010.
If you grind .0065 off one side, where do you remove the remaining .0035? bearings usually come in undersizes of .010, with plus or minus .001
You need to move the centerline .0065 to achieve .013 offset

Re: Offset grinding crank ?
 

The center-line of the crank pin is moved .0065 away from center-line of mains. If stroke on stock crank is 3.483'' instead 3.480'' and the pin is on the high side of tolerance it will make a stroke of 3.493'' grinding it .010'' under to the low side. But usually it takes a .030'' under on the rods to get .013'' stroke. If the index is good why not make it .014'' long?

Re: Offset grinding crank ?
 

Larry has it correct , it is a math exercise. The one thing that you also must realize is that indexing can not be fixed much by grinding. As an example, a 3" stroke crank would take a move of .026 for each degree it is off. to move it that much, it would need to be ground a minimum of .052 under.

Re: Offset grinding crank ?
 

Would you then have the rod journals chrome plated to build back to a std bearing? Or some other method. And would it be worth offsetting to a shorter stroke, if allowable to gain piston to valve clearance so as not to sink the valve job,in a piston without valve reliefs?

Re: Offset grinding crank ?
 

I never heard of anyone hard chroming a crankshaft to bring up a surface thickness. I thought it was like nitriding, to give a harder surface so the bearings doesn't bite into the journal.