J.B. ATOM GLOW REBUILD

 

Here's the engine as recieved needing some very large amounts of TLC.

As usual, first step, dismantle and assess for what's required.

 

O.K. so quite a bit needed so lets get started.

 Upon closer inspection we've found a rather alarming crack in the original crankshaft so this part will need to be replaced.

The cracked crankshaft has also damaged the crankcase main bearing surface so we will have a rumage through our parts bins and see if we've got another case and shaft available.

Having found a good second hand case and shaft, we also spotted an original spinner nut as well, we have cleaned and reassembled the case and shaft etc ready for the next step.

Good usable case and shaft.

And all nicely cleaned and assembled along with the spinner nut we found as well.

With the original piston being screwed onto an aluminium carrier we will dismantle this assembly and make a conventional piston and gudgeon pin set up which we believe to be a much better, easier to make and service, system than the original overly complicated and harder to outwork method used.

Here's the original needle valve assembly cleaned and refitted to the replacement crankcase.

Here's the rest of the original parts from the engine that was sent in by Adrian.

Next step is to dismantle the piston assembly and measure it all up to make the replacement parts.

Here's all the cylinder assembly parts dismantled and cleaned.

Now it's anto making the tooling and replacement part blanks.

Here's the new con rod all finished and ready to fit to the engine.

The old and the new.

The old piston rod assembly weighed in at 7 grams and the new piston rod assembly came in at just under 6 grams so a bit of an improvement in the reciprocating mass. While there is room for a bit more weight saving we went for the more reliable and less likely to distort piston option for this rebuild.

New piston fitted to the engine.

And the cylinder liner fitted up.

Cylinder head and a new glow plug.

Now we'll make a new backplate gasket and refit the back plate and tank.

Now its off to the test stand to turn some fuel into noise and smoke, YAY.

 All finished and ready for the trip home.