Throttle conversion for Cox tanked engines
 

Does any one have any experience with this R/C carb conversion from Cox International?

http://www.rcuniverse.com/forum/atta...mentid=2109521

How is its performance?

Why will it not work with SPI?

I suspect it WILL work with SPI-just not very well...! As I understand it (and I don't have an example to check) the throttle is obviously a simple barrel-which can obstruct the air intake tube-which will only regulate the amount of air taken in, not fuel-so such throttling as is achieved occurs largely by richening up the mixture considerably when the throttle is operated-and to a slight degree reducing overall mass flow-so a smaller charge is inducted. SPI will lessen the effect because it allows another route for air to reach the crankcase other than through the reed induction system-thereby acting in opposition to the throttle. Depending whether or not there is a fixed bleed hole in the throttle barrel, some degree of idle optimisation may have been achieved-which in turn would be upset by the presence of SPI. If not then I would expect the effect of SPI to result in poorer throttling-a reduced throttle range and higher low speed throttle revs.....I hesitate to use the term idle as these small engines usually 'idle' at about 6,000 rpm.....-or putting it another way, crude throttle setups like this usually result in halving the full speed revs- a 2:1 ratio as opposed to a decent throttle with fuel metering as well as mixture control (however achieved) where a 5:1 high speed:low speed ratio or better- is often achievable...

'ffkiwi'

Check my youtube vid. I did some testing for them. https://www.youtube.com/watch?v=pvpmLy0ToYE https://www.youtube.com/watch?v=pdnC55uOhfk

Ace used to make something like these throttles. I noticed Bernie is making them up now. http://coxengines.ca/throttle-for-co...bee-style.html They can use the tank mount.

The throttle will work with any Cox .049 reed engines. It will also work with SPI although the lower idle speed may suffer. Use of a hotter 1/4-32 plug with adaptor head will provide the best/lowest idle. Cox Engines offers a variety of glow plugs and adaptor heads for the throttle modification.