I have noticed that a few people are using micro switches in their builds rather than a correct points system as Brian has shown above. Jan Ridders uses them sometimes and the practice should be frowned upon purely because of the figures involved.
Let us have a look.
The average micro switch is guaranteed for 3 million operations.
Say the engine is running at 5K rpm.
3,000,000 divided by 5,000 = 600. That equals minutes running times.
So after 10 hours running, you are into failure time, and maybe a lot less due to how smooth the cam is ref wear on the operating arm or whether there is oil and other nasties about.
How do I know this.
We had a second hand multi million pound envelope making machine being installed by a Belgian firm. Their engineer had broken one of the magnetic sensors, which stopped the machine running, so as a temp fix, he wired in a top quality microswitch and told the top brass it would be ok for a few weeks while he put the broken bit on back order.
I said it wouldn't last, and he convinced the upper echelon it would.
Half way through the first night shift, the machine stopped, with no engineering staff in the factory. I was called in on triple time plus a day off in lieu, and wired in a small generally available mag sensor. It was still running perfectly 5 years later when I left.
How would you feel if your car broke down after 10 hours use?
Use the correct points system, they are designed to last, or a magnetic sensor or even a TIM electronic job, you will not regret it.
If you are into basic electronics, here are a few easy TIM ignition systems you could use on your engine. I used to use the TIM 6, and it works great.
http://www.5bears.com/tim4.htm
John
