The new Cam

Ok, The new cam was made after much difficulty. I machined a cam that was just perfect. I took it to my dad's house to harden it, and then disaster struck! When I took the first cam to be hardened, everything went smoothly. But this time, not so. My first mistake and probably my main error, was to put the oil for the quench in a plastic bottle. I took an old soft drink bottle and cut it to the depth needed for the cam to be submersed in. I then heated up the camshaft to a bright red ... then I dropped the cam into the PLASTIC bottle of oil .... the camshaft dropped to the bottem of the bottle, immediately melted through the bottom, caught on fire ... burning oil started running out of the bottle ... the bottle began to melt .... it fell over on it's side the remaining oil poured out onto the floor. The camshaft was laying on its side in a melted and burning bottle, still VERY hot. After the fire was put out and the cam cooled I looked at the cam. It was VERY warped. I have been told that drill rod will break if you try to bend it after it is hardened. I thought "I will just anneal it and do it over." No such luck. After a more careful examination, I noticed that there were 2 cracks in the cam. This cam is history!

I proceded to make another cam ( I am getting quite a collection of cams). I have learned a lot about cams and hardening real fast. This one went off without any problems.

I installed the cam in the engine, and before running it, I also made a new set of rings. The rings seem to wear very fast, and the compression drops off. I also made the rear cover with motor mount. The motor mount has rubber dampers that allow the motor to move a small amount. When the motor mount was added, the carb had to be moved. So, while I was making a new carb mount, I decided to go with a bigger carb. The original carb was an OS-40 FP carb. The new carb was from an ASP-75. It is much bigger. It is so big that I expected to have problems.

After the engine was assembled and mounted to the bench (it was mounted with the new motor mount), I tried to fire it up. It would only run for a few seconds. It had to be choked with a finger almost closing the venturie for it to run. But this is the minor problem! The real problem is the vibration! This engine was run previously while strapped solidly to the work bench. It could not move at all. It would vibrate the bench, but that was all. Now it is mounted with the rubber mount that allows some flexing, and it literally shakes itself apart. Mostly the carb mounting screws will come out after only 1 or 2 seconds of running, and the engine sucks too much air.

The main problem is the balance of the crankshaft. I knew it was way off, but I really don't know how to fix it without making a new crank. Making a new crank might require a complete re-design of the engine just to get more room in the crankcase for the added size of the crankshaft.

Here is a new picture of the engine. I decided to paint it.

pic of painted motor

Below is a picture from the rear of the engine.

 pic of engine rear