A tiny diesel design of .020 c.i. capacity the Wee Dee

[modelmotor]

Hallo Ed,
My Holly Buddy project is ready now.The new piston and wristpinincluding a new crankshaft with a full web are ready too.Why so many parts over.The Crankshaft was OK and last year a few short runs with the old parts were Ok as well,but the complete finish looks much better now.
The Piston is the bottle neck it needs to have a very good fit and that's in my case not always easy to make,but as far as i can feel and see when i give it a flick all looks very good to me!
----------------------------------------------------------------------------------------------
Your latest small model engine the tiny diesel engine The Wee Dee of 020cilinder capacity is a very good looking small modelengine.You might be very proud on it because it's even more difficult to make the fits from such small engines perfect.You succeed in making a small diesel engine with a same capacity as the legendary American Cox Pee Wee also with a cilinder displacementof 020 ci capacity.My congratulations are for you Ed.
--------------------------------------------------------------------------------------------------------------------------------------------------

I send you a photo from my ready to run Holly Buddy and one from my just started project the NOVA 1 (4,5 cc) a home building project of course.This NOVA 1 engine is ready ,but is missing the inlet tube and spraybar assy+needle,gaskets very important,new compression lever,propdriver,nut and the crankcase which was just a part of not identify alloy/titanium has been made up till a nice looking Cankcase which was a lot of work i must say i also much have to find a good way to find a better place to put my cilinder mounting screws through.I got this parts engine from an old friend of mine a Welshman.His friend the owner f this engine died a coule of years ago so now i own it to continuate the construction.The last three photo's are made from my NOVA 1 4,5 cc longstroke single cilinder model diesel engine to give you an idea.Thank you also for given me your idea of using my old piston from the Holly Buddy.I think that it wil work after that heat treatment.

 

[edholly]

Hadn't run this little guy in a while, somewhere lost the original venturi and tried using a cobbled up affair from a Cox engine. That didn't work. So couple days ago set about making a new one in brass, 2 mm throat, 2 mm screw as the needle. Made a holder and whittled the needle down to almost 1mm to go into the delivery tube of the venturi which had a 1mm hole that the needle enters. Spent a couple of hours trying to get a run - started easily but ran out of puff when the prime was used up. This arrangement used a tiny ID tube 3 inches long to the open tank. Went to bed last night not happy with it, then the light bulb lit - the tiny suction on the inlet was probably too much for the engine to draw fuel that far through such a tiny tubing. So this morning mounted the open top tank under the venturi - and this was the result. Live and learn !

 

[Maris Dislers]

Well done Ed. By my calculations of effective choke area, your engine needs to turn minimum 8,400 RPM for decent fuel draw. Can get away with slightly lower speed when run on the bench as you have arranged, with minimum "lift" needed. Getting that right is oh so important, as gravity feed is fraught with troubles. My diesel converted Cox TD 020 was lousy until I blocked off over half its intake throat to achieve acceptable incoming air velocity when turning 6x3 propeller.