![]() ![]() Now the MSD ignition is nothing new to me. Everything appeared in working order so I buttoned it back up. I then hooked it up to the MSD and tried it out. Bingo, I could manually trigger the lamp. I grabbed something from the drawer and soldered it in. After a few minutes of digging around inside, it appeared the transistor used to trigger the unit had failed. One circuit board with a handful of parts and I could see how they could sell it so cheap. I decided to check my light, but one small problem. Maybe that's why my stuff was always so slow. I had used it for so many years to set motors. I started wondering how bad my low end timing light was. No where could I find where anyone provided details about how they tested timing lights for accuracy. Some timing lights claimed to be compatible with them.Īll of this caused me to try and find more details about timing lights as I did not want to buy the one that's 5 degrees off and would like one that worked with the MSD. They mention that there were 5 degrees of difference between them! The following is the link: Īnother thing I have read was that there are problems when using a timing light with a multi-spark ignition. I came across a forum where someone had posted about 4 different timing lights they had. I thought I would try and see if anyone had wrote anything that compared some of them to help me narrow my search. It was difficult for me to suppress my thought of making something even better. There are so many to choose from! As usual, some companies claim they have the most accurate, some have lots of features, like digital tachometers. ![]() I thought there would be much nicer ones available.ĭoing a search on the internet I was amazed what is available. I pulled it out last night to use it and it had not self rejuvenated so I decided to look for a new timing light. I checked it and indeed it had died so I tossed it into a drawer. It's very old, made of cheap plastic, bottom of the barrel stuff. I had loaned out my timing light and was told it was not working. 00002778 sec.Īll systems that don't calculate the timing from the previous cylinder's firing event exhibit this retarding phenomenon to some degree (pun intended) and unless someone figures out a way to repeal laws of physics as old as the universe, that's just the way it is. Each degree is 1/36,000th of a second or. At 6000 RPM the trigger is still 37 degrees but the crank moves 6 more degrees in the same time it took to move one degree at 1000 RPM so the light shows 30 degrees.įor some perspective do the math: 6000RPM / 60 = 100 revolutions per second X 360 degrees = 36,000 degrees per second. To see the timing be 36 degrees at 1000 RPM the actual trigger event (points open, VR triggers, Hall effect switches, whatever) will have to be 37 degrees. The crank will travel 6 times as far in the same amount of time because it's going 6 times faster. To illustrate (these numbers are not actual, but for example only), if the ignition and timing light use 1 millisecond every firing and that is one degree at 1000 RPM, it will be 6 degrees at 6000 rpm. The bottom line of all this, and the reason you see the retard in your timing (all else in good shape, no mechanical gremlins like the cam walking) is at high RPM the crankshaft moves more degrees closer to TDC in the same amount of time. Xenon is most common in modern timing lights and more desirable for two reasons, its brighter white light and faster rise time than Neon which has an orange light. Xenon and neon are the gases in flash tubes. The bulb in the timing light has a fixed time it takes for it to achieve incandescence from it's off state. For the device to function each transistor in turn must switch from off to on. ![]() ![]() The difference in rise time between CD and induction systems is often mentioned.Ī device that has a lot of transistors in it, like the detector or pre-amp in an ignition system or the micro-chip calculator in an adjustable timing light, can be pretty slow because it has a slew rate for each transistor and the delays are additive. It's common to see a '˜rise time' specification for ignition systems and particularly coils. In the case of ignition amplifiers, magnetic triggered or otherwise, the devices have a fixed time from the trigger pulse to the change of state of the output. Įvery electronic circuit has a fixed amount of time it requires to change state from off to on or from one voltage to another. Every part of a circuit has a time constant, in electronics jargon called '˜slew rate'. All electrical devices have a fixed time it takes for them to perform their function. A phenomenon you guys are experiencing is the "slew rate" of the circuits in all the electronics involved, the ignition amplifier, the rise time of the coil, the rise time of the voltage in the plug wire and at the spark gap, and last, but not least, the slew rate of the timing light. ![]()
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