McCoy Sub Piston Induction?

I just added a second McCoy .35 Redhead to my collection, and it seems to have sub piston induction. In other words, when the piston is at the top of the compression stroke, the bottom of the piston is above the bottom of the exhaust port, like sub piston induction Cox engines. My other Redhead McCoy does not have this "feature". Anyone
here know anything about this?

> I just added a second McCoy .35 Redhead to my collection,
>and it seems to have sub piston induction. In other words,
>when the piston is at the top of the compression stroke, the
>bottom of the piston is above the bottom of the exhaust
>port, like sub piston induction Cox engines. My other
>Redhead McCoy does not have this "feature". Anyone
>here know anything about this?

Ron B.
F4Fguy

I have some with and some without.there may be a clue in that,of the ones I own,the later ones are the ones with it.I've never seen anything in the literature other than to say that the Redheads had it.It may be that the later,throttled RC types would not tolerate the sub piston induction and (Testors being VERY cost concious)simply made them all the same.Of course it may also be that production tolerances were such that "stackup" made some come out one way and some the other. I've never seen any perceptible difference in CL operation whether with or without.

Sub-piston induction, or "free porting" has been around for a long time. The Old Time Orwick, Anderson Spitfire, Super Cyclone and perhaps others used it. The Cox TD series used it.

It's supposed to equalize crankcase pressure at the top of the stroke, in case there is still a partial vacuum in the case. I tried taping the holes in the cylinder on an Orwick 64. I could find no difference in RPM with or without!

I have many Red Head McCoy 35's as well as 29's and 40's. Only two don't have sub piston induction. The series 21 chunky case models however, don't have sub piston induction. My favorite trick is to take the c'rod, wrist oin and piston and put it in a Lighning Bar RH case and crank. Then you file the Series 21 head bolt holes inward and the S21 head bolts on. Now you have a ringed McCoy that is rebuildable. I had one in my GNobler at VSC. Runs good.

I have one McCoy redhead that has a higher deck height on the case where the cyllinder mounts. It seems to raise the exhaust port on the cyllinder somewhat. I haven't had a chance to run this one. I have so many others.

"SAVE ALL THE PIECES"-Phil Brown

>I have one McCoy redhead that has a higher deck height on
>the case where the cyllinder mounts. It seems to raise the
>exhaust port on the cyllinder somewhat. I haven't had a
>chance to run this one. I have so many others.
>
> "SAVE ALL THE PIECES"-Phil Brown

Ron B.
F4Fguy

Phil:

This is kinda what I was saying.a raised deck would reduce or eliminate sub piston induction.I have a sneaking suspicion that Testors weren't too careful about such things,especially near the end of production.

I know on every one of my old ST's that had sub piston induction, you could not use a restrictive chip muffler, or you would get a very rough idle and spuratic run. Switch to a Big Art tube muffler, it was a totally different motor, nice and smooth. For the R/C versions, the exhaust butterfly would probably exaggerate it even more. Maybe on the Mccoy's they were smoothing things out for muffler or R/C use towards the end of the production run?