what does this stamping mean

[r4daytona]

First, sorry I don't have a pic.  I'm at work and just wanted to post this. So here's a description.  Looked at a 440 this weekend.  On the pad it said F440 then that little Nazi kind of symbol and then an X  I know the F440 is 70 440 and that symbol has something to do with a journal size?  what does the X mean?   The date was 12   9   HP2

[Alaskan_TA]

Maltese cross with X = .010 undersize crankshaft. See the page at http://www.hamtramck-historical.com/images/TSBs/1970/D70-25-1%20page6.jpg

[r4daytona]

Thanks for the info.  Now the next question ... How/why does that undersize crank occur and does that make the engine less desirable than one that is not? 

[TCB]

It was a common issue that happened during the crankshaft manufacturing process. After machining, some forgings came out with crank journals a bit oversize, and some a bit under.  It would've been extremely costly (and an enormous scrap rate) if cranks were thrown away for minor tolerance issues...so they were machined within a specified minimum tolerance.  Other than using the right sized bearings and correct caps on a rebuild, I don't think anybody considers undersized journals to be a durability issue. When the factory built and engine with the compensated caps and bearings, they should have been just as good as any other engine out there.

Your machine shop will examine the journals and caps for wear, taper, out-of-round, etc. and go from there. In some cases even a "bad" crank can be salvaged by regrinding it along with some cap work (cutting down).  Your rods should also be resized in the same fashion....a good engine builder should have seen this occurrence many times and know exactly what to do.

No worries.  


EDIT:  for kicks, I checked out the .010" measurement and its equivalent to about 2.5 mm's.... just a bit thicker than the average plastic trash bag.

[John_Kunkel]

I don't think it was an issue with the original forging so much as it was with "oops" grinding incidents.

[kiwitrev]

It was a common issue that happened during the crankshaft manufacturing process. After machining, some forgings came out with crank journals a bit oversize, and some a bit under.  It would've been extremely costly (and an enormous scrap rate) if cranks were thrown away for minor tolerance issues...so they were machined within a specified minimum tolerance.  Other than using the right sized bearings and correct caps on a rebuild, I don't think anybody considers undersized journals to be a durability issue. When the factory built and engine with the compensated caps and bearings, they should have been just as good as any other engine out there.

Your machine shop will examine the journals and caps for wear, taper, out-of-round, etc. and go from there. In some cases even a "bad" crank can be salvaged by regrinding it along with some cap work (cutting down).  Your rods should also be resized in the same fashion....a good engine builder should have seen this occurrence many times and know exactly what to do.

No worries.  


EDIT:  for kicks, I checked out the .010" measurement and its equivalent to about 2.5 mm's.... just a bit thicker than the average plastic trash bag.

2.5mm is the same as 1/8th inch did you mean 0.25mm

[TCB]

Yep 0.25 mm's.  That's what I meant, thanks.