Differences between Sure Start And Product Engine With Horseshoe Backplate

I mistakenly posted this before I was done writing.. There will be edits..     #1259 product-engine horseshoe-backplates.. I ordered several direct from Cox between 1990 and 1994. Mine are all black-plastic. At some point in between those years, Cox started shipping the backplates with their newly-designed flanged-cap reed-retainer. My 1st order of 3 backplates were the circlip-type retainer/housing. I ordered a total of 7 backplates spanning those years, for use on my balsa models with external fuel tanks. That's when I first started designing my own little C/L sheet-wing/profile models.. and it was joyous.. because they flew pretty good.  



Looking-over my Cox replacement-parts sheets (1991, 92 and 94..) I see that in 1994.. the part# is listed as 1258.. with the description; Backplate Carburetor (Only) w/cap..

I placed orders with Cox over that span of years, all requesting #1259 backplates.. see below;





Note that the carb/backplate price increases from $2.25 in 1991.. to $3.35 in 1993. I think that this was when Cox redesigned the backplate for the first time in several years; since their first modular 190/290/postage-stamp design.

Both of my Cox RTF airplanes had black horseshoe "circlip-style" backplates. They were my PT-19 Flight-Trainer and Cosmic Wind. The circlip-style are all broken now.. except for a single "white plastic" one (1st photo bottom-right).. not sure where that came from. There wasn't a crankcase with it when it came into my possession. I think that the aluminum needle and black Neoprene fuel-line are original.



The newer "flanged" cap-style retainer took a while to grow on me.. I remember thinking.. what's this??  

Here's a diagram that Cox sent with the part.. after they'd redesigned it.



That was it.. no case-gasket is shown.. only this illustration. This would lead me to believe that a case-gasket would still be required.. and  be installed over the cap and against the case. I'm guessing that this is as far as "Cox" took the design.. prior to being acquired by Estes?

Fast-forward to last month.. and there's the Sure-Start backplate parts that I bought bulk-discounted from Cox international. Backplates/snorkels in 3-packs x2 and snap-on retainers 10-pack x1.



I bought 6 short-needles, some Mylar reeds and a Tee Dee radial-mount from ExModel Engines.



In 2012.. a couple years before joining CEF.. I ordered some Cox engine parts from Mini-Glow Planes.com in Texas.



Some Sig Champion "25" 1/2A glow-fuel.. a Bee crankcase (which would Bee used in my CEF "Reed-Speed" engine).. a small Sullivan clunk-tank and an assortment of reeds; oval-shaped in the familiar Mylar (.005" thickness).. but also offered in Steel (.002" thickness).. and Teflon (.010" thickness). This intrigued me.. because I'd only had prior-experience with the Berylium/Copper-star (.001") and the .005" Mylar reeds. I have not tried either the Steel or Teflon. The "Steel" reed; I've read can wear the anodizing off of the seat of a tanked-engine. Being .002" in thickness.. I'd be curious to see how that reed might run in an early plastic backplate/carb designed for the circlip-retainer/.001" Copper-star reed??

There are also "Crystal" (acrylic) reeds available.. as well as "CEF Store" experimental Mylar reeds to test.

I have been a proponent of the Cox .049 reed-valve engines. They carried me into this hobby!