Engine Blue Printing - 1275cc A-series - Crankshaft #2

DISCUSSION:

• Ok, the mysteries of engine #2 continue with its crankshaft.  Take a look at the pink rectangles.  Now compare them to the other cylinders above.  For some odd reason, the #4 position on the crankshaft has a significantly different half stroke than the others.  Depending on which method I used to measure the length, it's either 0.004" or 0.005" shorter.  Hmm, do you think this will affect the compression ratio in cylinder #4?  Let's see that's a volume difference of 0.49 cc or 0.030 in^3 with a stock piston diameter and 0.005" of half stroke difference.   You tell me if that's significant.  So, I doubt this was our friend, the Butcher of Cylinder Heads.  This odd attribute came from the factory.  Hmm, you guys starting to wonder what's in you 1275?  I still need to measure crankshaft #1.  Hopefully, it will not have the same attribute.  Because it if does, then this seems like one of those ridiculous engineering fixes that happen more often than not for things like overly hot #4 cylinders.  If you have any thoughts on this, please chime in.  I would love to track down the reason for this.  In the mean time, I should get back to crankshaft #1... curious once again.

SUMMARY:

• Besides the above mentioned oddity, this crankshaft seems to be ok.  I wouldn't want to stick it in a performance motor, but for a stock configuration...  Also, I would like to get a bit better straightness measurement.  But, I need to run over to a friend's machine shop and borrow the manual lathe for a bit to measure it.

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