Greg the glow bar type glow plug is actually a throw back to many years ago now when the design of our two stroke model engines were simpler in design. The top of the single transfer port exited the cylinder directly across from the exhaust port but in the way was a deflector or dam on top of the otherwise flat piston top.
The idea was to deflect the incoming charge up and in a loop fashion into the combustion chamber. I suppose that's why they called it loop scavenging. The down side was and keep in mind this was when the RC carbs were really something new on the block, that this fresh charge aimed directly at the glow plug tended to quench the fire during low throttle conditions. Well this glow bar over the coil of the glow plug actually was a pretty good fix for this problem at the time. Now fast forward about thirty five years at least and I cannot think of a single engine any more that uses this loop scavenging and the glow bar plug is quite redundant.
The A6 is the same as the older A3's and quite hot I use those for my smaller engines and the 25/35 AX's for my larger AX,'s ( .55, .65. .75 and .95 ) I also prefer the #8.
John
Last edited by JohnBuckner; 07-26-2014 at 08:30 PM.