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Discussion Starter #1
So I check the bores on SWMBO's 4.0 pushrod (now that it is dissassembled). Book says max out of round is .005, max taper is .001. I have .002 out of round in number 3, .001 everywhere else. Max taper is .002 in same cylinder, all others .001. What should I do? It looks like I could just get it honed to put it right back in spec. All my measurements are on the low side of bore limits. I intend on driving the crap out of this thing (many miles, not necessarily "abuse"). Should I go .010 anyway? The cost difference is of course significant. New rings and bearings, or new rings, bearings, and pistons and machine work (boring versus honing)
 

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Bore it .010 , you will be glad you did . Old worn pistons like to slap . You would be surprised that the pistons are worn worse than the walls of the cylinder . If you wanna do a cheap fix , ring it . If you want to do a proper fix and have it run for many miles , slap some pistons in it . Id say you'll add maybe $200 for new pistons and machining . While your there have the machine shop tank the block and put new cam bearings in .
Like I said , around 200 .
 

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I'll assume the larger OOR dimesnsion is along the thrust side of the bore. Post a picture of the major thrust side of the most out-of-spec cylinder, along with a picture of the attendant thrust side of its piston. This cylinder wouldn't happen to be #1 or #5? What's the current average P/W dimetral clearance?

If nothing odd appears, new standard pistons, rings and a honing (with a flexhone) should be acceptable. I'm guessing pistons are expensive, yes? *G*
 

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Discussion Starter #4
The one thing I have learned during this process so far, is that 4.0's aren't being rebuilt in home garages because of parts cost. There has to be at least a couple of Sagans (being billy-uns and billy-uns) worth of these motors out there, yet the cost for the individual components are very high. I'll try to get a pic of the offending cylinder (6, btw) and piston tonight. IIRC, the skirts looked great on all the pistons. I did not measure the P/W clearance in situ. I will replace the piston in that one and measure as well. From what I'm hearing though, I still need to buy new ones (at $30 each, and $90 for the ring set!) Ouch.
 
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