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G'day Johnny Would you be willing to share your STL file? Rob.

Did you find the drawings?

G’day Pat Your Viper looks and sounds great. When you finish your second viper with with the different transferpassage method it would be interesting to see whether it gives any improvement to the performance.I have toyed with trying the other transfer passage method shown on the drawings.

G’day Pat here are some photo’s of the tool that I made to cut the exhaust ports on my Naylon Vipers as well as one of the one of the spare cylinders I made

Gday Pat if you imagine a very short HSS parting tool with an increased front clearance so that the heel of the cutter does not rub, and minimum side clearance on both sides. I will find my cutter on the weekend and take a photo and post it here. When cutting the ports I I fed it in slowly and...

G’day Pat I’ve found that the simplest and most accurate way to cut this style of exhaust Port is to use one of the boring tools that accepts1/8” high speed steel. Use the end that holds the tool bit at right angles to the axis of the tool holder. Sharpen the tool so it resembles a miniature...

Gday Pat I usually use teflon for my gudgeon pin end caps.

I forgot to mention you can buy delrin in rod or sheet form as well. Also you don’t get the furry fibre on the cut edges.

G’day Pat when I made my pair of Naylon Vipers I used Delrin for the discs. They worked brilliantly. I have used delrin on at least 6 other engines without any problems.

In July 1986 I purchased a set of drawings from Forest Edwards for his 5 cylinder radial engine. I started to build a pair of these engines but found a problem with some of the parts that I made and at the time shelved them until I could come up with a fix for the mistake. Any how I solved the...

G’day Creast When I made mine I machined the cap from delrin and then machined brass inserts which were assembled and then soft soldered in place. The biggest problem I found was finding brass tube small enough for the fuel intake and ended drawing it too the correct diamater using a drawing...

Would you have a copy of the STL file for the crankcase that you would be willing to share? Rob.

Can I make a suggestion . The crankcase has a small counterbore to align the cylinder and there are only two screws to hold it all together . I would put a small stepped flange at the bottom of the cylinder to give a better bearing or sealing area. I found it very difficult to tighten...

As Aerostar said the flat on the backplate is for piston clearance first turn the crankshaft through bottom dead centre and see if you can feel if the piston is binding on the backplate or even better machine the flat on the backplate as designed . Also check that there is no leakage on any of...

Fair enough my mistake. I obviously wasn't paying attention.

G'day Modelmotor After looking at the photo's of your crankshaft with the undercut section of the shaft adjacent to the intake port on the shaft I would be very interested to know how well your motor runs. Because by machining away what looks to be, between .010" to .020" off the diameter of the...

G'day Naiveambition I have fond memories of South Bend lathes from my apprenticeship days. Your finish problems could come from a number different areas. 1. always make sure that your tool is dead on centre unless you are boring and then have the tool above centre. 2. Make sure that the compound...

G'day Werowance from past experience, store bought diesel fuel is often low on the volatile component of the mix, so the home mix fuel is always a better bet, provided you can get the ether. Also only mix enough fuel for running on the day. On the crankcase leakage also check around the front...

G'day Werowance I found your story again. Firstly, don't let someone else have the pleasure of starting your new engine for the first time, I would encourage you to persevere. From the sound of things there could be a number of things going against you. I would suspect that the fuel you are...