I originaly had the engine balanced back in '69. Had a piston checked when I replaced it in a rebuild in '80. This time I am replacing rings, rod bearings, rod bolts(ARP), had rods re sized, and the clutch has been replaced in the interm. Is re balancing just a good idea or is it necessary at this point? Plan on turning it 6000 to 6200+ on a regular basis.

I say yes, absolutely for your circumstances and yes in general because it's really not very expensive in the grand scheme of things.


Lawrenceville, GA

For the ‘complete’ rebalancing in your case, in theory that’s a “No”.  Reality my dictate otherwise.  Even regrinding a balanced crankshaft undersize does not require rebalancing as the material being removed from the journals is being offset by the use of thicker bearings.  It is recommended however to have the rods end weights rechecked to insure that the weights are all the same after replacing the rod bolts and resizing them.  Any weight variances in excess of a ½ gram should be addressed.  If there are any questions about the quality of the original balance, then a complete rebalance should be considered.    And because you have done some replacements in the clutch area, at least consider rebalancing of the flywheel and clutch assembly. The flywheel, pressure plate, and clutch disk can be rebalanced without rebalancing the remainder of the rotating engine pieces as they are ‘neutral’ balanced.

Lorena, Texas (South of Waco)

Thanks Ted. That makes good sense. I will talk to my machine shop and see what he says also. Not sure if he does balance work there but if he does not I am sure he has somone he sends it out to. I would rather be safe than sorry but no need to throw money at fixing something that is not broken. It is a shame the company that did the original work is no longer in business. They were still in business in '80 and were able to easily check the new rod and piston because they still had the original specifications from '69

Ted pretty much covers it.  If you "Change" anything it's a good idea to re-balance if you are just "replacing" parts with the same part there shouldn't be a problem.

   God Bless.   Tim                           http://yblockguy.com/

350ci Y-Block FED "Elwood", 301ci Y-Block Unibody LSR "Jake", 312ci Y-Block '58 F-100, 338ci Y-Block powered Model A Tudor

tim@yblockguy.com  Visalia, California    Just west of the Sequoias