Recent content by edholly

Crankcase is typical of most 2 stokes, the oil in the fuel lubricates everything and the adjustable top is the contra piston, it is used to vary the compression - most model aircraft diesels (really compression ignition) engines need around 20 to 25 to one comp to run. The ether has a low flash...

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...

Hi Rodrigo, Have been playing with this after a year of it sitting on the shelf. It is a sweet little runner and I think well within the bounds of a second or third build for anyone interested. Did you ever get around to finishing the plans we worked on a while back ? Kind regards .. Ed

Hi Sheraz, if you look at the front housing it is 28 mm wide and 30 mm high - so the centre is 15 mm from the bottom (or top) ... cheers .. Ed

I have started a register of Holly Buddy's that have been built - if you have made one could you please add it there. Can be found at https://www.homemodelenginemachinist.com/threads/holly-buddy-build-register.35234/#post-397063 Would love to see Chris do the same for the Boll-Aero Ed

5. Holly Buddy Mk 3 ... Wanting to make it look a little prettier - uses screw threads to attach nose, backplate cylinder and muff. Screws at the rear also hold it from turning. Looks totally different but it is the same inetrnals - just different clothes !

4. Holly Buddy Opposed Twin. This one is 2 Holly Buddy's opposite each other. It cheats a bit and uses the cheeks of the intermediary bearing as much as it uses the bearing itself. Figured no worse than running an engine as a pusher where the prop driver runs against the crankcase in a plain...

3. An inline twin version, basically 2 Holly Buddy's joined together - the crankshaft feeds the 2 crankcase cavities though inlet ports in the crankshaft 180 degrees apart.

2. The Mk2 version. Made using a pattern and then a casting which I had hoped to be able to supply at reasonable cost, but it turned out to be rather more expensive than I had hoped.

1. The prototype. The first one built.

I know there have been quite a few Holly Buddy's made and thought it would be great to have a register of them and those engines based around it. As it was HMEM where I first wrote up the build of the prototype, would be good to have a listing of completed builds here. Maybe a few photos and a...

Started the new HB (Mk3) yesterday - fired and ran a few seconds in my hand ... today drilled the mounting holes and put in the test rig and ran very nicely, easy to start - in fact it started 4 times on case fumes after the 3rd 1 minute run. Haven't leaned it out yet or wound the compression to...

Here is my next edition of the HB - using screw thread everywhere to hold it together and to allow for the muff to be a nice fit on the top of the cylinder. Piston, rod, prop driver and washer to go. Been a long project - started about 10 weeks ago - things keep getting in the way. Plan is to...

Stunning, stunning work, Patrick. Love the sound they make when both cylinders on song. A bit more temperamental than say a Taplin Twin as - as you say - it is really 2 engines liked together with a common shaft. Would love to see the plans on Outerzone one day.

I have been building and designing model engines now for quite some years and have been modelling for over 65 years. I have designed from scratch about 11 model diesel engines and built them and they all run - and have had a couple put on CAD by kind fellow enthusiasts. I would like to have a...