seeking teedee 0.049 wisdom to get me sorted

Loosening heads is a sign of work hardened copper gaskets. Replace with a brand new one.

As far as vibrations go, the engine will vibrate, how is the mount and structure around it?

Mounts need to be rock solid! Prop balanced of course...

I have repaired cracked carb bodies many times. I use a piece of brass tubing. I can't recall, but I believe 5/16" tubing. This provides a nice tight fit. I fit the tubing to the neck of the body. This requires a conical radius on the bottom and a bit of filing on the top. This is easier done with a lengthy piece of tubing due to being able to hold it and file it. Once it's fit as tightly as possible to the lower section of the body, make two scribe marks and cut it off filing the top. It's much better to have the neck of the tubing slightly below the factory plastic as this will allow the needle valve assembly to sit on the plastic. I then soak the part in alcohol, rough up the outside with sandpaper and apply epoxy on the outside. Hit it with heat and allow the epoxy to flow into the cracks. Press the ring on and let it sit. I then chase the threads with a 1/4-32 tap when done. It's better than new as the tubing really pinches the plastic tightly allowing you to tighten the venturi tight.

I have to ask why the 2 pitch prop? That prop is offering very little sending the engine into some fairly high rpm's which more than likely has the engine running above it's maximum torque curve. That in itself is going to cause vibrations. The TD does prefer a little load just not a overload. As Brad stated, if the piston socket has excessive play using that prop could possibly offer contact with the head.

The APC FF prop has a well designed airfoil and makes good work of the air.
The prop is a bit beefy so the 2 pitch helps to keep the rpm up to a reasonable
level is why the FF folks like them, less torque issues on launch too. It really is
a good prop for steady fuel flow rpm kept up insures a good run. Folks should
try them more often with low weight speed planes the flight can be thrilling as
thrust is near constant through out the flight.

I have a few (9) Teedee 049/051 and always DECK the Glow heads on a granite block with 600 grit and light oil..NOW flat..I use brand new copper gaskets from Ex or Bernie...Cox or Galbreath heads NEVER loosen on my engines...Ever

I have a few of the aluminum carb bodies but find the replacement Plastic version more compliant with fewer air leaks...I like the metal versions but the nylon and rubber gaskets are iffy..IMO...too easy to distort.... I do not use any gaskets or O rings for the Plastic carb body...but I do pay strict attention to torquing the assy in place

IMO small 1/2a engines need to be squeaky clean and AIR TIGHT!...then anything for %25 to %65 Nitro with at least 20% oil

Looks like my piston may have been contactong the head, there was some significant slop. Depending how much I run this motor I end up re-setting it periodically. Will use some new head gaskets and possibly sand the head using a mirror I'll keep my eye out for a small slab of granite. I did that for a past glow head that had some corrosion and would not seal. It looks like the cox international ones have a machined surface to help with sealing, I can see parallel ring on it.

Wow Ken I'll have to use this tubing solution for sure on a new to me 0.09 I'm going fix up. It has a crack in the usual place. Thanks for describing the procedure. I'll use this on some of the cracked venturi bodies in my part pile to. I heard some guys were wrapping fishing line and coating with epoxy to accomplish the same goal.

Hi Cribs, the engine is mounted to a scratch build beam mount skyray I made. It seems pretty solid but the wood did squash a bit. I may need to make some thin aluminum plates at some point.
https://www.coxengineforum.com/t11381-scratch-build-skyray-with-beam-mount-for-0-049-teedee

I'm more experimenting with the prop pitch, our local guru recommended the 6x2 which echoed 1/2a nut's basis. I fly at 3500ft above sea level, so far this realy seems to help get the motor in the powerband for a good high speed flight with nice string tension. But I've only made one flight so far, my opinion may change.

A piece of glass is a good surface to lap the head on.

Flat glass...mirror will be fine... or any fairly flat surface...600~800 grit a a bit of oil...aluminum does NOT need much working to get flat

Over kill and relatively expensive I have a 12x12x3 granite surface that is certified to .001...BUT I have only ever used to to lap crank cases and heads

http://www.grizzly.com/search/?q=(granite+AND+surface+AND+plate)+OR+(granite+OR+surface+OR+plate)

Hey Fredvon4, thanks for the link. They have some awesome stuff. This would also be super handy for knife making and for general machining work to. I'll have to add to my wish list.

Yah i here yah does not take much to remove material from those little glow heads. Does not need a guerillas touch that's for sure.