I suggest you try a 4-40 pressure tap-you will probably find them on one of the cl stunt or cl racing websites. People like Joe Klause of Kustom Kraftsmanship and Fox used to manufacture them as accessories-but these days they are a bit thin on the ground. As an alternative-if you have a lathe-or access to one-then a cheap way is simply to drill out a brass machine screw to a suitable ID, thread a nut on and solder it, and cut off the screw head-it won't look terribly elegant (unless you machine off the threads above the nut)-but the fuel line will cling on just as well if you leave the threads on.

The G-Mark ..061 radial mount is easily copied-it is simply flat aly sheet attached to the engine with the original backplate screws...the originals are not very common-nor are the plastic ones for the .03-but not hard to create a copy. I will draw my one up, and scan it (with a suitable rule included) so you can print it out full size as a template. The UK's Mike Billington did the only published test on the G-Mark 061-published around 1985 in 'Aeromodeller'.....to the best of my knowledge there has never been one published on the .03. If you have the means-and the inclination, Billington indicated that the engine responded well to more nitro-but needed cylinder shimming to increase the exhaust timing to properly benefit from this-and likewise an adjustment to the head insert depth. Reading between the lines-the head itself could benefit from a bit better design-either to take an insert, or a Nelson or turbo plug.

ChrisM
'ffkiwi'