Tiny Throttles
 

I am looking for some ideas to convert small diesel CL/FF engines to R/C. I've got an Enya .09 carb I was hoping to use on a small A&E I acquired. The Enya carb has a shank size of 7mm. I need about 6.4mm. (I can still probably use the carb in another engine.) I've also got an OS carb that weighs a little less, but it has a bigger shank. I don't have much in the way of machining tools. I'm just looking for resources/ideas for getting tiny carburetors that can be used on sub 1.5cc diesels. Thanks, Scotty

The problem is to find small carbs for a good price, but the Enya 09 carb is a very good place to start. If you don't have a lathe to reduce the shank diameter you can also drill or ream out intake a little. I did that on a Philtech Diesel and it worked well. The Enya 09 carb is also a direct drop-in on the PAW 09 diesel.

https://www.youtube.com/watch?v=E_PRqDNAsDs

The issue here is how big are the engines you're trying to convert-the Enya 09 carb is a great carb-but only suitable for engines in the 1-1.5cc range.The original OS Max-10 carb also works well in this mode.... 'Small' to some of us means <0.5cc-to others it may be less than 2.5cc! If you're talking about very small carbs for 0.6cc or less then there is only one option-the PAW55 carb-not in my my opinion a very good one-but that's all that's currently available. The Schlosser 0.5 and 0.25cc were excellent-but no longer available, the cox 05 carb has a 1/4-32 threaded shank-the MP Jet and small Enya carbs are flange fitted. Without decent machining facilities there are not too many options available. The Enya 09 and OS Max 10 carbs have been fitted to the MK-17 diesels in the past and performed well. There might be something available from CS for their small sideports-but availability I suspect is questionable. The PAW 049 and 06 diesels seem to work quite well in R/C mode-I've seen photos of throttled Mills 75s on the Net-but never of a Merlin, or a Frog.... the MP Jet carbs are probably the best designed for purpose-but would need considerable modification to adapt to a shank fitting (for 'modification' read 'machining work'.....)
You could also look at the little PAL 020 engine-I don't know if they're selling the carb separately. The issue with small diesels and throttles in particular is the very small throttle bore required for effective throttling-which generally means a 'specific to engine' solution, and such carbs do not necessarily transplant well to a different brand and size.

You could also use the Thunder Tiger RC carbs from their .10 and .15 engines too. I put a .10 carb on a Russian MK-17 2.5cc diesel a while back and it worked OK for me.
There are some small throttles made for the Mills .075 and 1.3cc engines that pop up for sale from time to time too. Red Fin Engines in the UK sells small throttles that fits the Red Fin engines too. Cox Engines in Canada has a little throttle body made to fit the Cox .049 engines and it would work in some cases with other engines too.

nvengines.com (formerly norvill) sells the r/c carb for their .04-.07 engines. I have no idea what the spigot od is but you might ask.