OK, I know this might sound obvious to some, but as an aeromodeller who returned to the sport last year after a break of around 23 years my engine knowledge kinda goes as far as PAW diesels. This is what everybody used back then in our club for C/L.

My query is this; after building up quite a collection of various diesel and glow engines (British, Jap, and US) why is it some people fit the liners of the Fox 35X/36X back to front (or reversed). I know they'll run in this detuned state, but it doesn't really make sense somehow.

While I can understand rotating the liner a little to detune such an engine are people doing the above deliberately, or simply out of ignorance?


Any ideas,


Tim

My query is this; after building up quite a collection of various diesel and glow engines (British, Jap, and US) why is it some people fit the liners of the Fox 35X/36X back to front (or reversed). I know they'll run in this detuned state, but it doesn't really make sense somehow.

While I can understand rotating the liner a little to detune such an engine are people doing the above deliberately, or simply out of ignorance?

Yep, its ignorance and a mistake to do this.

Consider that there was even an official exploded engine brochure printed once that actually showed a Frog with the head and baffle topped piston in the reversed order , so even the 'experts' can get it wrong at times.

Tim,
The Fox or any other 2 cycle IC engine will not run with the liner ports reversed.

  I don't think anyone is doing it on purpose for detuning. But, they certainly will run with the liner in backwards. It will run very weakly and get very hot, typically, but it will definitely run in most cases.

    Brett

  A couple of years ago, on E-Bay, there was a Fox 35 up for sale that showed in the picture, that the head was bolted on one hole off (appx 30 degrees)  He even showed one picture of it running!!.  I bid outrageously just to get the engine to see what was going on.  Not only was the head on wrong, the cylinder was 180 degrees off (but the piston WAS in correctly with the baffle on the bypass side), and the needle body was installed with the spray holes parallel to the air flow instead of perpendicular to the air flow.
  In that condition, with a 10 X 6 master Airscrew cut down to a 8.5 X 6 and Fox superfuel it tached out at 8500 RPM.  I took it apart and installed everything as it was supposed to be and again tached it---9600 RPM  Both settings were in a hard 4cycle run.  I would have never believed it if I hadn't seen it myself!!   Try it.

  Bigiron

   Added by edit-- I forgot to say that the head was one of the later stock types, not the old "Ranger" heads.

Bigiron

  I have seen that one, too. It runs much better that way than it does with the liner backwards, but still not very good.

     I also know that a 40VF will run, very poorly, with the piston in backwards. You wouldn't think it would make much difference with flat-top piston, but there is a cutout in the piston skirt that has to be on the intake side. And no, in this case, it WASN'T me that did it.

    Brett

Would you come close close to getting sub piston induction with the boost port cut away uncovering the exhaust port at TDC?

Years ago there was an OS .46VF on Tower's "Scratch and Dent" section for like $30.  The engine had hardly been run and for good reason.  The liner was in backwards.  I don't know how that happened since there was a tiny pin to align it correctly.  PaPa Dave Hemstraught gave me a new P/S (he had switched to an AAC set up) and I put it in.  The engine ran great after that.  It evidently came from the factory like that.

BIG Bear
RNMM/AMM