Original Posted By: "Douwe Blumberg"
Subject: Pietenpol-List: Balancing rods and pistonsDoes 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 differencesin 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 performanceincrease doing this and I'm not even certain if making everything weigh the same produces less vibration, especially in something as small as a ContinentalA-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________________________________________________________________________________
Pietenpol-List: Balancing rods and pistons
Re: Pietenpol-List: Balancing rods and pistons
Original Posted By: Rcaprd(at)aol.com
Subject: Re: Pietenpol-List: Balancing rods and pistonsSterling,I weighed my pistons and rods before assembly, and they turned out very close. I didn't do anything to get them any closer. I suspect those V W enginesturn up over twice the rpm of our Continental engines, where balance may be more crucial. Chuck G.________________________________________________________________________________
Subject: Re: Pietenpol-List: Balancing rods and pistonsSterling,I weighed my pistons and rods before assembly, and they turned out very close. I didn't do anything to get them any closer. I suspect those V W enginesturn up over twice the rpm of our Continental engines, where balance may be more crucial. Chuck G.________________________________________________________________________________
> Pietenpol-List: Balancing rods and pistons
Original Posted By: "hjarrett"
Sterling,If you want to have a go at balancing the rods etc yourself, get a copy of Richard Finch's book "How to keep your Corvair alive".There are diagrams in it that show how to build jigs to balance the engine parts.I haven't yet done this myself, but it looks simple enough.Cheers,Rod WoollerChidlow, Australia>From: N321TX(at)wmconnect.com>Reply-To: pietenpol-list(at)matronics.com>To: pietenpol-list(at)matronics.com>Subject: Pietenpol-List: Balancing rods and pistons>Date: Sat, 9 Oct 2004 08:48:29 EDT>>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>>Protect yourself from junk e-mail: http://microsoft.ninemsn.com.au/protect ... __________
Sterling,If you want to have a go at balancing the rods etc yourself, get a copy of Richard Finch's book "How to keep your Corvair alive".There are diagrams in it that show how to build jigs to balance the engine parts.I haven't yet done this myself, but it looks simple enough.Cheers,Rod WoollerChidlow, Australia>From: N321TX(at)wmconnect.com>Reply-To: pietenpol-list(at)matronics.com>To: pietenpol-list(at)matronics.com>Subject: Pietenpol-List: Balancing rods and pistons>Date: Sat, 9 Oct 2004 08:48:29 EDT>>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>>Protect yourself from junk e-mail: http://microsoft.ninemsn.com.au/protect ... __________
Re: Pietenpol-List: Balancing rods and pistons
Original Posted By: N321TX(at)wmconnect.com
I did a full dynamic balance on my Continental A-65. Since it was going into acertified plane (Taylorcraft) the IA checking my work on the rebuild wanted allthe work done before he looked at the parts. After the stock car engine builderdid 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 insideof the piston skirts to get them in balance (had to exchange a couple of pistonsthat were VERY light which he said were probably "inclusions" in the castings).Next he made sure all of the wrist pins and caps matched afterwhichhe mated up specific caps, pins and pistons to get the TOTALS to match (stop tolerancesfrom 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 therods not only had the same weight, but their CG was in the same place. Finallywas a dynamic balance of the crank and cam. He spun the crank on a balancelathe 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. IFit had come out of the lathe I can't imagine the damage it could do. He seemeda 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 andI should have an incredibly smooth engine. Remember it takes power to shakean engine and that's what vibration is. If you get rid of the vibration youget 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 ifit doesn't make a measurable difference it was a blast to be there for.Hank J ----- Original Message -----
I did a full dynamic balance on my Continental A-65. Since it was going into acertified plane (Taylorcraft) the IA checking my work on the rebuild wanted allthe work done before he looked at the parts. After the stock car engine builderdid 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 insideof the piston skirts to get them in balance (had to exchange a couple of pistonsthat were VERY light which he said were probably "inclusions" in the castings).Next he made sure all of the wrist pins and caps matched afterwhichhe mated up specific caps, pins and pistons to get the TOTALS to match (stop tolerancesfrom 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 therods not only had the same weight, but their CG was in the same place. Finallywas a dynamic balance of the crank and cam. He spun the crank on a balancelathe 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. IFit had come out of the lathe I can't imagine the damage it could do. He seemeda 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 andI should have an incredibly smooth engine. Remember it takes power to shakean engine and that's what vibration is. If you get rid of the vibration youget 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 ifit doesn't make a measurable difference it was a blast to be there for.Hank J ----- Original Message -----
Re: Pietenpol-List: Balancing rods and pistons
Original Posted By: "hjarrett"
Subject: Re: Pietenpol-List: Balancing rods and pistonsGood 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/eb10 ... __________
Subject: Re: Pietenpol-List: Balancing rods and pistonsGood 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/eb10 ... __________
Re: Pietenpol-List: Balancing rods and pistons
Original Posted By: N321TX(at)wmconnect.com
Me too. It will probably end up in my other plane (41 Taylorcraft) when its enginetimes out before it goes into the 45 Taylorcraft that is taking an eternityto finish. I hope it meets everyone's (that worked on it) expectation. TheNASCAR engine builder that did the work said one reason he did it was becausehe had never worked on an airplane engine and it was his off season. If itworks as well as it looks it will be a champion.Hank J ----- Original Message -----
Me too. It will probably end up in my other plane (41 Taylorcraft) when its enginetimes out before it goes into the 45 Taylorcraft that is taking an eternityto finish. I hope it meets everyone's (that worked on it) expectation. TheNASCAR engine builder that did the work said one reason he did it was becausehe had never worked on an airplane engine and it was his off season. If itworks as well as it looks it will be a champion.Hank J ----- Original Message -----
Re: Pietenpol-List: Balancing rods and pistons
Original Posted By: Clif Dawson