"Lightning Bolt" McCoys vs. "Standard" McCoys

Depending on the year the engine was made, the plug position on the head was changed. Some say it makes a difference, I say it really doesn't. The lightning bolt case also featured a bronze bushing in the case. Essentially the changes to the case lugs were to umbrella the use of other engines. The lightning bolt has the slotted holes and these would interchange with K&B's etc. All in all a sales tactic. Duke Fox recognized this early on which is why the stunt .35 was designed to have the same footprint as the O&R engines. He made his engines fit the same bolt pattern to put a damper on O&R engine sales.  The gated or as you stated birdcage cylinders are used for ringed pistons. Mccoy or Duro-Matic probably had a oversupply of these and I've seen them in several Mccoy's non ringed of course. I also found the gated cylinders to be the ones that always wore out for me. I'm told a Testor's series .21 .35 piston (Aluminum) dyke's ring piston fits into that .35 gated cylinder making it a hybrid. I can't comment if that's true on the .19's. I had a few hybrids and I wasn't overly enamoured with their performance. Most of your period models of the time called for a .19-.35 to fly the model. While I've seen the smaller mills used, it fit the beginner and the models flew better with the larger. The .19 is really a oddball size. The .19 was also the topic of discussion in one of Model Airplane News magazines Jan. 1968 in which the clearly stated that inferior materials were used to reduce cost and that the engine literally wore itself in the test article. The company was contacted in regards to this matter and they responded that they were well aware of it. The testing party was reassigned a revamped .19 in which the piston was hard chromed which put a end to the problem. For as much exposure as I have to these engines, I'm starting to think this is a bit mythological.  I've yet to come across one of these. This was known as the Mccoy Custom R/C. These had the gated cylinder. I also found the .19 to have a highly annoying exhaust note and it really is louder than the .35.

In addition, the article suggests no difference between the redhead control line version or the blue head r/c version. their findings were as followed. Of the two test  engines received, the trouble was in no way related to excessively lean runs or due to inadequate lubrication. At this juncture we moved to communicate our findings to the Duromatic Products company.

I personally had a brand new right out of the box .19 do what was claimed above right in front of me. This has also been true for some of my .35's as well. I personally believe that the year the engines were made are very crucial to their longevity. Some of us had good results, others bad. I experienced more bad than good but I do have some good runners currently and I intend on keeping them that way. Ken