RE: Breaking-In a sideways oriented engine
 

Tenure??
Oh please Mum, tell me how I can do that?
I'll be good cos I don't want to have to "restart"....promise...

RE: Breaking-In a sideways oriented engine
 

Okay, time to "bait and switch "here. How many of you guys have experienced this on your glow engines and can prove your problems are related to an egg shaped piston? This whole thing to me rates somewhere around the who gives a sh[X(]!

RE: Breaking-In a sideways oriented engine
 

I was trying to show that this is not a problem, or that it is fairly insignificant. But a fairly insignifcant problem that could be as bad or worse than the one submitted.

RE: Breaking-In a sideways oriented engine
 

Just to get back the the O.P. question...IMO it doesn't matter if it's side mounted for the break in.

I can see how the cylinder could tilt forward...because the rear of the cyl. and outer portion of the case there is hotter, and expanding more than the front of the case where it has the cooling air flow impinging directly on it. (the engine I had in mind when I wrote my previous post about the larger "polished" area at the rear is a Webra .50 BTW-FWIW )

As far as OOR (Out Of Round ) is concerned...have you ever noticed that if you take a piston/pin/rod assembly (holding them with your fingers ) and gently push it up into the sleeve to test for the pinch, that if you rotate the piston(rod, etc.) 90 degrees, that the point where you start to feel resistance or drag will change? I mean that you can tell that the piston / sleeve have worn into a slightly OOR condition? You need to do this without handling the parts too much so your body heat doesn't change the O.D. of the sleeve before the piston...or, hang on to the parts long enough so that your hand warms up everything equally.
That's one way I can quickly test for OOR...the other is with bore gages and a mic. of course, but I usually just go by feel.

RE: Breaking-In a sideways oriented engine
 

Yes, I've noticed that just by eyeballing but I've never gone to the extent of actually measuring the point where the pinch varies. Personally I don't think it matters a hoot if it's slightly out of round because it's been run in to get the correct clearance all the way around for the original setup. It might be a bit different if the piston was mounted with a ball and socket arrangement like the Cox engines use because that allows the piston to spin while it's running like unpinned rings turn.

As for the uneven heating, some engines are built with the cylinder about 1/2 degree back from vertical so they'll straighten up when up to temperature. Usually this is only done with rear exhaust engines though where heat is more concentrated at the rear. A forward facing exhaust is considered to be the ideal but it gets a bit complicated trying to get at the carb. The Taipan 40 had a forward exhaust port but the casting for the exhaust was turned off to the side for the muffler mount. (Photos lifted from one for sale right now).

RE: Breaking-In a sideways oriented engine
 

I don't think the OOR matters much as long as you get the sleeve back in the exact same position. That's not hard to do if the sleeve is pinned, but some engines...the above mentioned Webra .50 for example, are not pinned so you have to be very careful as to alignment when re-assembling. (not to mention disturbing the wear pattern, but that's another topic, huh? :D)