Thanks again rsv1cox "Bob"

1/2A Nut wrote:Take a look at this pic the engine is not ready to run

dckrsn wrote:Somewhere around here, I have a backplate with the
spraybar drilled clean through. I forget whether was a
product or postage stamp plate.
Bob

It seems to me that I've also seen that.... but I can't dispute the fact that this one's in there backwards. I only had two other horseshoe backplates to check, which do NOT have mesh-screens on the air-intake. One is a red high-flow "Killer Bee" clone.. and the other is almost identical to this one in question.. (white-plastic with an aluminum needle).

Here's the other white one..




That pretty-much confirms it.. I just checked a "postie".. and it's the same.. and has only one spray-hole. Same with the high-flow back-plate.

I hadn't removed the reed from Bob's engine.. because it seemed to operate properly. Had I done that.. or taken a look at this other backplate; I might have noticed it.

I've never removed a spray-bar from one of these.. but I guess I'm gonna' have to try it. I would assume that I should try to align the "splines" when pressing it back in? I've read about swapping-in a fine-thread NVA, so maybe this will be good practice for when that time comes..

Anyway...... "THANKS" for saving me some grief, because I was anxious to bench-run it later-on today.

Another handy use for the K & S assorted cut-offs I got through Tower Hobbies. A 1/4" dia. x 3/4"L. solid brass rod was the perfect size for pressing-out the spray-bar in my bench-vise.






not perfectly-centered.. but close enough..




Not a tough job at all..

Oldenginerod wrote:

There are those who will tell you that there is an optimal angle for the spray hole to be on, which is not "perfectly-centered".
Some claim 15 degrees from perpendicular to the air flow for a Cox engine.

Personally, knowing full-well that we have discussed this at length before, uncovering a plethora of opinions, I would put it as close to centre as I could, being the position that I have personally witnessed most factory installations to use.

Yes, I remember some conversation about that. Allow me to inject my own thoughts and blabber on this subject..

Being that the tanked reedies' non-obstructing fuel spray-hole is exactly perpendicular to the airflow, there's probably some logic there. The product (tank-less) back-plate is a different animal though. What puzzles me is; the tanked engines' venturi-shape is the reverse of a conventional velocity-stack. Maybe it has to be, because of the fuel-jet's location? Turbulent-airflow occurs immediately as it enters the backplate and fuel-atomization is probably further enhanced by a pressure-wave produced by the megaphone-effect as it approaches the reed.

The product (tank-less) back-plate has to rely more on the spray-bar to augment laminar-flow into turbulent-flow for fuel-atomization.. but has the advantage of flowing a higher volume.

Whatever the case.. there's no disputing that these little engines are engineering marvels!

rsv1cox wrote:It seems I got all those engines in the right hands, I know that you guys are enjoying them.

Many came with other engines, lets say Enya's as a package and I just set them aside.  I still have scads to clean up, if I start now, maybe by Christmas next year.  

"Let's say Enya's"... .. (I'd love to see your collection someday Bob!) .......... another cool little engine that Bob sent in his "care-package" was a Cox buggy engine.



Lots of cool parts there! I think that the backplate is fitted with a fine-thread NVA.



I'm not sure about that.. but it looks like one. If it is; it's the only horseshoe-style backplate that I have, that sports one.

Sooner or later.. I'll want to try running a pressure-bladder fuel-feed.. and a fine-threaded NVA would be the ticket. That aside; there's other interesting aspects to this engine. The heat-sink.. and muffler.. the flywheel/fan assembly.. and the I believe it may have a H/D crankshaft. Cool stuff! I'm not sure of the cylinder-porting.. but the CEF "cylinder-identification" archive might give a clue.

The engine is "stuck".. but may only be castor-seized. I'll probably tear it down this weekend to find out more.