Pietenpol-List Digest Archive

Sun 10/10/04


Total Messages Posted: 4



Today's Message Index:
----------------------
 
     1. 05:07 AM - Re: Balancing rods and pistons (hjarrett)
     2. 07:46 AM - Re: Balancing rods and pistons (N321TX@wmconnect.com)
     3. 09:39 AM - Re: Balancing rods and pistons (hjarrett)
     4. 09:58 PM - Re: A "no shackle" question (Clif Dawson)
 
 
 


Message 1


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    Time: 05:07:32 AM PST US
    From: "hjarrett" <hjarrett@hroads.net>
    Subject: Re: Balancing rods and pistons
    I did a full dynamic balance on my Continental A-65. Since it was going into a certified plane (Taylorcraft) the IA checking my work on the rebuild wanted all the work done before he looked at the parts. After the stock car engine builder did his thing a normal check was done by the repair shop at the airport. The balance guy matched all of the pistons and took a light shave of the inside of the piston skirts to get them in balance (had to exchange a couple of pistons that were VERY light which he said were probably "inclusions" in the castings). Next he made sure all of the wrist pins and caps matched afterwhich he mated up specific caps, pins and pistons to get the TOTALS to match (stop tolerances from adding up). Next he did the rods by weighing them from both ends (use one hole as a pivot and weigh the other). He did this both ways so the rods not only had the same weight, but their CG was in the same place. Finally was a dynamic balance of the crank and cam. He spun the crank on a balance lathe to over 20,000 RPM looking for balance and harmonics. THAT WAS SCARY! I never saw something as massive as a Continental crank spin THAT fast. IF it had come out of the lathe I can't imagine the damage it could do. He seemed a little amused at my concern and said stock cars go MUCH higher. I haven't run the engine yet but the IA said he was impressed by the numbers and I should have an incredibly smooth engine. Remember it takes power to shake an engine and that's what vibration is. If you get rid of the vibration you get more power at the prop. I just wonder if it will be measurable. All told I think I paid less than $200 US for all of the balance work. Even if it doesn't make a measurable difference it was a blast to be there for. Hank J ----- Original Message ----- From: N321TX@wmconnect.com To: pietenpol-list@matronics.com Sent: Saturday, October 09, 2004 8:48 AM Subject: Pietenpol-List: Balancing rods and pistons Does anyone have any experience in balancing rods and pistons? I have a highly accurate digital scale used for weighing letters. I've weighed my rods and pistons (separately) and have found some minor differences in weight. (Have not weighed them with bearings and pins yet...) I knew guys in El Paso who balanced the rods and pistons on VW's they raced in Baja and the Mojave desert, but I don't really suspect you get a performance increase doing this and I'm not even certain if making everything weigh the same produces less vibration, especially in something as small as a Continental A-80 engine. I suspect even if you get all the pistons and rods matching in weight, there are still some minor issues with true balance of the crankshaft, making the "balancing act" of the rods and pistons overkill. The guys who balanced their VW engines, believed there would be less stress on them. Thoughts and comments appreciated. Sterling


    Message 2


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    Time: 07:46:46 AM PST US
    From: N321TX@wmconnect.com
    Subject: Re: Balancing rods and pistons
    Good points and I thank all who replied. I remember the VW racers were really dealing with high RPMs and the VW engines were really hopped up. I also submitted a bid on Ebay for the book Rod recommended. I found a good article on engine balancing and it was an interesting and informative read. It can be accessed at this URL. Dynamic and static seems more than my postal scale can handle and for $200, it seems like a small fee to pay for all the work the tech did on the Continental 65. I'd like to see that 65 run someday. http://www.babcox.com/editorial/ar/eb10330.htm Thanks, S.B.


    Message 3


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    Time: 09:39:12 AM PST US
    From: "hjarrett" <hjarrett@hroads.net>
    Subject: Re: Balancing rods and pistons
    Me too. It will probably end up in my other plane (41 Taylorcraft) when its engine times out before it goes into the 45 Taylorcraft that is taking an eternity to finish. I hope it meets everyone's (that worked on it) expectation. The NASCAR engine builder that did the work said one reason he did it was because he had never worked on an airplane engine and it was his off season. If it works as well as it looks it will be a champion. Hank J ----- Original Message ----- From: N321TX@wmconnect.com To: pietenpol-list@matronics.com Sent: Sunday, October 10, 2004 10:44 AM Subject: Re: Pietenpol-List: Balancing rods and pistons Good points and I thank all who replied. I remember the VW racers were really dealing with high RPMs and the VW engines were really hopped up. I also submitted a bid on Ebay for the book Rod recommended. I found a good article on engine balancing and it was an interesting and informative read. It can be accessed at this URL. Dynamic and static seems more than my postal scale can handle and for $200, it seems like a small fee to pay for all the work the tech did on the Continental 65. I'd like to see that 65 run someday. http://www.babcox.com/editorial/ar/eb10330.htm Thanks, S.B.


    Message 4


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    Time: 09:58:31 PM PST US
    From: Clif Dawson <CDAWSON5854@shaw.ca>
    Subject: Re: A "no shackle" question
    <003101c4ae71$330e2900$6501a8c0@Nancy> <006a01c4ae76$fc2a48a0$42705118@dawsonaviation> <005701c4ae84$fad97d50$6501a8c0@Nancy> --> Pietenpol-List message posted by: Clif Dawson <CDAWSON5854@shaw.ca> Yeah, I drew it out to see and it would be something I would not want to have to try. 9 years! I just posted a few more pics to mykitplane. This is as far as I have gotten in 10. I figure another 5. Why is it so many other things seem to get in the way of the truly important things in life? :-) :-) :-) http://www.mykitplane.com/Planes/photoGalleryList3.cfm?Start=61&AlbumID=27 Clif > --> Pietenpol-List message posted by: "Bert Conoly" <bconoly@earthlink.net> > > > Cliff > I think you'd have a real hard time getting the nicopress sqeezer thingy > into a 4 inch inspection hole > That's why it's taken me 9 years, 4 months and 3 days to build my plane. > (But that suckers about ready to go.)




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