ST2300 conrod, wrist pin end

[Bob Pastorello]

Ed - the only conrod wear issues I had with the ST seemed to be related to running the bigger props and higher nitro.  I think the sheer mass of the larger load puts more wear on the upper part of the conrod.  In my situation, though, I also saw similar wear on the lower end...If I kept the nitro around 22-25%, 18% oil, and the load slightly less, things improved.
    As always, YMMV, and I could be *completely* wrong.

Bob Pastorello, Oklahoma
NSRCA 199, IMAC 1320, AMA 46373
rcaerobob at cox.net
www.rcaerobats.net


  ----- Original Message ----- 
  From: Ed Miller 
  To: discussion at nsrca.org 
  Sent: Monday, June 23, 2003 9:41 PM
  Subject: ST2300 conrod, wrist pin end


  Any of you folks out there that have been running ST2300's ever experience a short lived wrist pin end of the con rod ?? I have approximately 100 flights on a ST2300 in a Hanson Dalotel spinning an APC 18x8 with S&W fuels 20% to 30% nitro ( 20% oil in all fuels ) and the bushing in the wrist pin end of the con rod is worn out. I'd say there is at least .030" clearance, maybe more. Engine was down about 700rpm on the ground and never really settled on a rpm and acted lean in the air, in verticals it went flat, would no longer haul plane vertically indefinately. This all happened in maybe 5 or 6 flights, went from a powerhouse to a dog. There is only one small hole in the top of the conrod to lube the wrist pin ( approx .040" in dia. ), the wrist pin is fine and measures no wear at all where the conrod rides on it. I'm going to order a new conrod, if the new one only has one hole in it I may enlarge it a bit as well as add a second hole from the bottom of the wrist pin boss on the rod. Luckily I have a 2nd ST2300, just installed it and I'm back to 8800 rpm on 25% nitro with the 18x8 so I'm ready for the Pocono pattern contest. Both my ST2300's are Italian made, the only notable difference is one has a longer crankshaft ( prop end ).
  Thanks...Ed M.
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