Break-in of tapered bore engines
 

HomeBrewer,

This is exactly right.

I use the short-primary-runs method, but some of those who replied to my thread; http://www.rcuniverse.com/showthread...59&forumid=145

say this was necessary only for Meehanite (cast iron) pistons.

This annealing process may work to a lesser extent, with the materials of tapered bore engines, as some wrote. But it doesn't hurt so I go on using it.
I help many in my club with their break-ins.

Sincerely,,

OS46FX - strange performance-PLEASE HELP
 

Dar, What is the metallurgical effect (and advantage) of annealing in this case? I have an old metallurgy book collecting dust on a shelf... so toss in all the technical words you wish - I'll look them up. :)

OS46FX - strange performance-PLEASE HELP
 

Jim...for the best description I've come across regarding the metallurgical affects on Meehanite go to http://www3.telus.net/dieselcombat/breakin.htm

I very much doubt there's any similar process needed (or possible) with an ABx but there's no harm in short runs anyway. But I have to agree with jaka...I don't think the running in process is as critical as is thought. There must be a million FX's out there run in with OS's instructions that were written for ringed engines.

As for the earlier peeling problems, I suspect OS fixed it by going to a different plating sub-contractor. Of some interest, George Aldrich noted that with the earlier liners virtually none ever peeled if used with 22% oil.

OS46FX - strange performance-PLEASE HELP
 

I have a dazzler and have experienced the same problems you speak of. While I'm running on older OS 40SF, I think the engines are close enough that my solution might work for you as well. I elevated the tank 3/4 of an inch from the bottom of fuel tank compartment. The top of the fuel tank now almost touches the hatch cover when I put it back on. If you refer to your engine manual, they show a diagram on where the carbureter spray bar must be in relation to the fuel tank. I hope you get your engine running right, as the dazzler is a fun airlplane to fly. BTW if you're using a Great Planes 6 oz tank, I would strongly suggest you replace it with someting else that uses as better system ot spreading out the rubber stopper, my fuel tank leaked shortly after I started flying my plane, I"m using a du-bro 6 oz tank now.