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Dean, Thanks for offering to help with split bigends, I can see that is the only real way to make this engine now. Unfortunately I am about to start on the restoration of a 1961 Lotus Elite which has to be finished by August next year, so building model engines will be a bit quiet for a while -...

Dean, I am jealous .... Beautiful work, congratulations on it. Like Neils would love to know how you split the bigends .... ? Ed

Designed as an easy to build model aircraft diesel engine of good performance and 2.5cc with notes to encourage modifications to the original design by any future builders. CAD plans done by Steve Jenkinson and the engine is dedicated to the memory of David Owen. This is the 15th engine built...

This engine has now been completed. The design and build took exactly 1 month to do. It is a successful design making 9250rpm on a 9 x 4 wood prop on its 4th run after about 15 minutes running, and improving in power with each run. The complete story is on the Works in Progress forum and can...

Here are the CAD plans for the Holly Buddy. Please read the "Forward words for Buddy Holly" before building the engine there is a wealth of information here. If you do decide to build it, would very much appreciate a PM to me. Ed

I was disappointed with the soft compression, entirely my fault, just machined the piston a tad too close to final finish to be able to get a good surface on it at the size I was aiming for and ended up .2 thou smaller than intended. When I measured it after disassembly and after the running it...

Here is the finished engine, the comp is in fact a little soft as said in the previous post, but that didn't stop it from starting reasonably quickly and running superbly. I ran it for about 3 minutes on a very rich setting and right at the end just tweaked the comp bar a bit and the revs rose...

Here's a photo fo everything washed in the ultra-sonic cleaner with kero and then Nulon Carby cleaner. The ball bearing finally had its protection seals removed and the grease inside washed away. The venturi was Devcon'd into the nose and then whole engine oiled up and assembled. The...

Mechanicboy, thanks for the insight as to how best to make and use a lap. I have found this simpler way for both cylinder and piston that works for me and is not as labour intensive. Obviously the way you describe will give wonderful results, but my way too gets the engine running pretty...

After making quite a few of these engines, you can still work out ways to improve what you do. Contra pistons have to be a tight fit in the bore, and I know from experience that a tight fit (contra) to a nice fit (piston) is usually .2 thou - so it will be interesting to see when we make it...

Here is how to work out the internal diameter with the bore gauge. Yes 1 (ie 1 to 2) division on the dial is 1 thou how accurate is that ! I take a number of readings as the gauge is more for comparison than measuring. I got 570.5 - 570.8 - 570.2 - 570.5 and the calipers said 570.5 ...

The next step is to lap the cylinder with not just a fine finish, but also a taper from the exhaust port to the top of about 0.1 thou. Yes, this is pretty fine tolerances, but I have achieved that using the lap that has to be made. The first thing to do is to clean up the bore with a reamer...

Next was making the conrod. I don't think anyone really enjoys this task, I certainly don't relish the thought of it. Anyways it seems to have come out ok. I think it was Ron Chernich who came up with this idea initially and this is a bit of a modification on that. I mount a drill the exact...

Couple of jobs done today. First the marking out of the crankshaft venturi hole at 50° BTDC. As can be seen a sharp needle will just mark the steel enough to notate where the opening is. Then with a centre drill just nick the metal till you are sure it is centred then put a lead in with it...

Venturi done - found it needed to be a little beefier than the design, so Steve will fix that in the plans. Also found Steve's interpretation of my hole in the crankshaft under the venturi was awry - so Steve will fix that too. Finding out now that mud map drawings are all fine and dandy for the...

Here is the muff, once again when Steve finishes the CAD plans, you will see how this one was made. Muff's are so distinctive and a small change in design can totally alter the look of the engine, so if you decide to build this engine, once again think of redesigning it to your own preferences...

This is the process I use to cut the "drive" into the prop driver. Very simple, and works a treat. Using the cross cutter move it about 3 thou into the work. I have divided my chuck into 20 divisions with a simple texta mark. Lining up the mark with anything thin and available I move the...

Job for the morning was to make the prop driver and washer. Now for a surf at Wanda beach. There are a couple of things about making the prop driver which might be helpful in other situations. The photos tell the story, but firstly I want to mention BOKUM tooling. I was very fortunate that a...

Thanks John, can see how the split collar frees up using the angle of the compound slide, I will try it in the next engine. I usually try to leave the angle set after putting it on the shaft, till I make the prop driver, that way I get a perfect match, but I have also managed to dial it in after...

John, Beautiful work, machining long cuts off centre is a pretty difficult exercise and just holding that sort of thing becomes a nightmare. Thanks for sharing it. Here is the almost finished crankshaft, just needs the venturi hole drilled when the nose is made and some weight removed for...