Looking for reasonably priced 531211 & 537466 through bolts

[an8pilot]

I agree with your assessment of the bolts of TCM s own online IPC and your diagram.

SB97-6B does say replace crankcase "thru" bolts. And as Bruce said on page C-2.4 of the M-0 of 2017 Table C-1. Mandatory Overhaul Replacement Parts says replace Crankcase "Through" Bolts

Per the Continental electronic IPC it depicts all 537465 and 537466 531211 and 531212 as thru bolts
http://www.continental.aero/support/ill ... talog.aspx

I've talked with Mark twice in the last two weeks. He is not the last word though without a specific listing by part number on their letterhead. He's a nice young fella.

I don't work on other people's Aircraft anymore due to liability and low pay. But after rereading everything I feel to be completely correct if I were to call it overhauled for a customer, (and not a repair or continued time on 337 as I'm doing here on my own engine), I would have to replace all 4 part numbers as they are all listed in their online IPC as thru bolts, but not the stud because that technically is not a thru bolt in SB97-6B in the general term or in M-0, but that is just my opinion. I also feel that the crankcase overhauler checked that stud when the case was overhauled, mating faces milled, and line bored, and although I did check the stud for tightness and depth in the case as to where it would fit in the other case half, I would not want to take the stud out as tight and sturdy it is in the case without having the crankcase overhauler do it. But that stud, and the 531211 and 531212 are what center the case by their tight fit of .0005 Tight to .001 Loose between the center shoulder and inside diameter of the thru bolt case holes Weber they fit together basically inside a 1/2 of the mating faces split line on each case half.

Interesting on Hydraulic Lifters (tappets) on on page C-2.4 of the M-0 of 2017 Table C-1. Mandatory Overhaul Replacement Parts says Hydraulic Lifters (tappets) must be replaced at Overhaul, but on
SB97-6B way down below numbered items and below the change notice bar paragraph starting All GTSIO520 starter adapter, it has one line involved with the same change notice dark border line "During overhaul, all hydraulic lifters (tappets) must be replaced with New or Factory Rebuilt lifters (tappets)." Kind of hidden there.

When I spoke with Mark he said all parts had to be purchased through distributors, and new hyd lifter tappets are approximately 89.00 each for the 12 but I saw no distributors selling a Factory Rebuilt lifters. I guess they left themselves an out when they overhaul engines at the factory. I will call again this coming week and ask.

If we are getting gold/bronze colors in the filter after break in from overhauling, which is could be thrust bearings not measured properly, rod end bushings, or rocker bushings, or aluminum because we didn't measure the cam for and aft clearance, or the Piston pins are tight with the cap up against the cylinder walls, and we take it apart as a precaution, we replace the main and rod bearings and rod nuts and bolts, but do we then replace all the thru bolts again? How about the lifters? Is it continued time? Prop strike has its own inspection requirements. Really bad Prop, maybe we should replace the thru bolts. Rods may be inspected. But if it's an overspeed over a certain RPM over ten seconds rods must be replaced. What about the thru bolts.