Wednesday, January 4, 2012

Confirming Engine Data Sheet Specifications

I'm going to check the specifications on the Engine Assembly Sheet provided with my motor against Tom Monroe's How to Rebuild Small Block Ford Engines book.  I'd just like to confirm everything is to tightened or set to the appropriate specification.



One of the first items on the specification sheet is the crankshaft end play.  The specification sheet indicates  my crank end play measures .005".  Tom Monroe states the measurement should be between .004" and .008".  My block seems to be setup perfect in this regard.

The main bearing clearances on my engine are all between .001" and .0015".  Tom Monroe's book does not indicate the proper clearance.  However, he states a .001" to .003" plastigage be used.  As a result, I believe my measurement is on the small side but otherwise fine.  Rick indicated it was tight but good when I questioned the measurement at the shop.  The same is true of the rod clearances as they are all .001".

The top ring gap for all the rings is either .022" or .023".  The instruction sheet which came with my Keith Black moly rings includes a calculator to reach the best end gap by multiplying .0065 by your bore diameter.  Based on this caculation, the gap should be at .026 so my ring gaps are a little on the small side but not hopefully it will not be an issue.

The second ring is suppoed to be gapped at .004" per inch of the bore.  For my 4.040 inch bore, this means the gap should be at .016".  The instructions state this is the bare minimum.  All of my second rings are at .020" with the exception of two which are at .022".  This should work out just fine.

There is no indicator on the instructions for the proper oil ring gap.  The build sheet I received from the machine shop indicates mine are set to .026 for all of the pistons.  I'm assuming these ae just installed as they come out of the box rather than gapping them.  After all, these do let oil through so the gap is not as critical. 

The spec sheet states the main caps were all tightened to 65 ft/lbs.  Tom Monroe's book indicates the proper torque is between 60 and 70 ft/lbs so this is again just right.  The rod bolts were all tightened to 24 ft/lbs and Tom Monroe states they should be between 19 and 24 ft/lbs so this is also perfect.

Overall, it seems like things were done mostly to spec and everything is real consistent from one piston to the next.  I'd like it to be perfect but I'm content with the results at this point.

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