A friend with a mid-50s Chevy 235 mis-torqued the rod nuts to 80 foot pounds. My guess is he read the specs for the main bolts. Anyway, 10 of the bolts held and two snapped. If it were you, would you replace: a. Just the two broken bolts b. The two broken bolts and their nuts c. All 12 bolts d. All 12 bolts and 12 nuts ... and like my 5th grade teacher Sister Mary HolyWater used to say, "Explain your answer."
d. All 12 bolts and 12 nuts. If two failed, the "ultimate strength" of those bolts was less than 80 foot-pounds. They yielded at less, but just plain failed at 80. Smart math says the remaining bolts are somewhere between yield strength and ultimate strength. Disclaimer: I may not be using the correct terminology (yield, ultimate). But... for the naysayers... just do a quick estimate of what ONLY one of those fasteners will cost in repairs, if it fails in use. I am expecting the "penguin" to rap my knuckles any minute!
I agree with Mike, and for all the reasons he presented. Cummins Diesel used to include a stretch gauge, with their factory overhaul kits, to check if head bolts were go/no go. I always wondered why guys would not just buy all new head bolts, what with all they had spent on the overhaul kit. AND...I would much prefer to break a head bolt, than a rod bolt. Steve.
Steve, good point. While I am acutely aware of the "while I am at it" replacement of "stuff" on Penny, a set of 12 rod bolts, with nuts costs... (OK, go crazy, spec the GOOD stuff, ARP's) next to NOTHING. And not even next to nothing in the BIG picture, just plain next to nothing. Example: I needed some long (metric) bolts to hang the 5.3 off the engine stand. I bought "10.9" bolts, which are equivalent to a standard Grade 8 fastener. $2.50 apiece as I recall. Long. Metric. 10.9. $2.50. Just replace them all, and never look back.
It's looking like the consensus is to replace all the rod bolts and nuts. I heard they are $15.00 each bolt, + nuts. Probably a good investment anyway! Anyone know of a cheaper source for the bolts? This is a mutual friend of Bill H and Me.
