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jdemaris
03-08-2004 05:27:09
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Re: Ring job? in reply to Kennyp, 03-07-2004 14:21:56
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Just as important as the bore is the groove in the pistons for the top ring. If it has subtantially more than .005" side-clearance it's going to give trouble, and a ring job is a waste of money. Years ago, it was common practice to rebuild pistons which entailed regrooving, shimming, and knurling skirts. Then, parts got cheap enough and labor high enough, that stuff just got replaced as a matter of routine. Now, new parts are getting high, and reclaiming or repairing pistons is well worth it. I recently did my John Deere 1010 engine. Previous owner had done a ring job but it had bad blowby. I pulled it apart, and checked top ring side-clearnace with a feeler gauge and it measured .012" Checked prices at the dealership, Deere wanted over $100 a piston, and there are four of them. So . . . bought four repair shims from Hastings for a total of $12, and spent $40 ($10 per piston) at a local machine shop to have the pistons regrooved. I've put 1500 hours on it since, and it runs great. I guess one catch is finding someone to cut the grooves. I started out going to a city automotive machine shop fifty miles from here. I asked about piston regrooving, and the head of the machine shop told me the process was obsolete, no longer done, and repair shims have not been available since the dark ages. Subsequently, I did a little research and found it's standard pratice on many race car engines. Researched a little more and discovered it's a common pratice in other parts of the world that don't have "throw-away" cultures yet. Checked Hastings website and they have lots of info. about the repair process. Called them up, they were great. They will sell rings and shims, one by one, if desired. Finally went down to a local machine shop in our village run by an older somewhat retired guy. He says he does a lot of them, charged me $10 a piston, and I had them back the next day.
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