Pietenpol-List: rebuilding an A65

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matronics
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Pietenpol-List: rebuilding an A65

Post by matronics »

Original Posted By: airlion
>From an A&P whom I respect=2C and who knows these engines very well: -OZThe connecting rod numbers face the top of the engine in it's flight position. What that really means is that the oil port in #1 rod should spray into #2 cyl and the oil port in the bottom of #2 rod should spray into #1 cyl. The same relationship exists between cyls #3 and #4. Another way to look at it is that the oil ports on the rod caps for #1 and #2 should point toward each other. The same for #3 and #4. About half of the Continental engines I tear down have rods in backwards. Usually # 2 and #4. That's a testament to how tough these engines are=2C not a testament to not needing the oil ports. Those oil ports in the bottom of the rod spray oil into the bottom of the opposing piston when at BDC to help cool the opposing piston.There is no specific orientation for the pistons. The A-65 pistons are cam ground=2C but they are also fully symmetrical as related to the axis of the wrist pin=2C so there is no up/down orientation.If the builder is going to the cost and trouble to rebuild the engine with practically all new parts=2C then I hope he does himself a big favor and balances the engine properly. The crank should be balanced=2C then the rods should be balanced end-for -end. That means the small ends should all weigh the same as their movement is horizontal. The large end of the rods move rotationally=2C so they should all be match balanced as well. Most engines have had rods replaced individually at times=2C so there is no balance relationship at all between the rods. I see them with quite a wide range of weights. The pistons should also be balanced along with the wrist pins. There is nothing like flying behind a properly balanced engine. Continental didn't do a particularly stellar job of balancing the cranks and the original rods were only balanced to match overall weights. It can be done much better and it pays off in smoothness=2C performance and longevity of the engine. ________________________________________________________________________________Date: Sat, 24 Sep 2011 17:41:59 -0700 (PDT)
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