min. flow required at optimal RPM?

I use a bit larger diameter fuel tube between the tank and the carb and add a short, smaller dia section just at the carb fuel nipple, to minimize pressure drop of fuel in the feed line. The only fuel starvation I sometimes experienced was caused by the commonly known air seeping into the carb along the needle valve stem, that we all cure by pulling that short silicone tube over the NV and the threaded end of the spraybar..with some care these COX  critters will never let you down..

Thanks for the replies gents.. I found a source for .031" ID X .062" OD silicone tubing.. which reduces overall weight when compared to garden-variety sm. size silicone line.. and could possibly be used in a micro clunk-tank/fuel pick-up application. Trying these things out is all part of the fun!

Hi friends. I received the aforementioned sub-micro silicone tubing a few days ago (a few days ahead of Amazon's delivery forecast)



This tubing is small........ but it does have a substantial wall-thickness.  



I love small stuff.. probably why I love the Cox 1/2A engines... and anything else that might contribute to their longevity.

I did pose the question of whether a higher-performance Cox 1/2A engine would be able to draw enough fuel through this lines' small ID... naturally aspirated..  to sustain combustion while running at full-bore.

This tubing may well be a better suited for .010/.020 displacement glow engines. I'll note my findings here.

As Ken Cook pointed out; the fuels' viscosity and ambient air-temperature will surely affect the flow-characteristics of the tubing.

Here's a photo comparing "this" tubing with the Dubro #221 (sm.) tubing.



Might this tubing work for a balloon-tank set-up.. as a perforated pick-up tube? It would make the most use of the available space inside the balloon.