GOTHAM DEEZIL REBUILD

 

First step in this rebuild was to asses the engine parts and decide on what work was actually required. This turned into a bit of a major as it turned out because the engine was so far away from being right straight from the factory. These Gotham Deezil engines are well reputed to be very poorly made on a good day and this example did nothing to enhance that reputation. The first part to come under close scrutiny was the crankcase. this needed the main bearing to be resized to give a nice true and round bearing so was sized up to 8mm diameter. After this was done I re-machined the deck height and cylinder bore hole as there was over half a mm difference in the hole diameter compared to the cylinder liner diameter which was giving absolutely no gas sealing between the two parts. This particular part of the rebuild was of  most importance due to the fact that it would ensure that the crank center line and the cylinder center line were perfectly true to each other and the cylinder hole would now be true and round.Photos below show the progress.

Next on the list for remedy was the crankshaft itself. This part was a total loss so a new shaft was fabricated out of 4140 round bar. This allowed us to make some design changes that were desperately needed to ensure long service life.The addition of the lube feed hole to the main bearing was an obvious fix to the original poor design.Photos below show progress.

These photos show the case test assembled with the new crankshaft and prop washer also made and fitted.

Next up was the cylinder liner assembly. This needed to be made from scratch to obtain the perfect gas seal fit between the case and the liner. As we were asked to build this engine for display running only and not for flying use we machined up a new cylinder liner from free machining steel which gives easy work-ability but also good running fits with easy starting when the correct fuel is used.

These photos show the finished cylinder liner with the cleaned up original cylinder head and compression screw ready to have the piston made and fitted.

Photos below show the whole assembly test fitted to the rest of the engine.

All that remains is for the honing and lapping of the cylinder liner and the manufacture of the piston and con-rod assembly.

Photos below show the piston/liner assembly completed and assembled to the engine

 

Now for the moment of truth