Modern Timing Lights and Six Volt Electrical Systems – Dave’s Garage

This month we have a question from Wendell Noble. It seems his trusty timing light has given its last flash, and he wants to know what modern replacements will work with older six volt electrical systems.

There is no simple answer. Most modern timing lights designed to work with 12 volt systems will actually work on six volts. Some, how-ever, will not. For the ones that won’t, a 12 volt battery or a battery charger will have to be used. Timing lights take power from a battery, but the trip wire feeds from the number one spark plug wire.

I have several timing lights, from a 30 year old Sears timing light, a cheap Harbor Freight timing light and an Actron advance timing light. These timing lights will work on six volts.

My advise would be to take a chance and buy a new timing light and try it. If the battery is near the front of the engine, I would hook up the light with the positive lead going to the positive lead on the battery, and the negative lead going to the negative lead on the battery, and the inductive trip wire hooked up to the number one spark plug wire. Chances are, it will work on six volts. If it does not, then the positive and negative cables will have to be hooked up to a 12V power source, (either an extra battery, a battery charger or a 12 volt booster pack).

I have been impressed with the advance Actron timing light I bought through Amazon. It was inexpensive, and it works well. With this light, you only need to find TDC on the engine. The light has a knob on it to advance or retard the flash. If, for example, the timing specification is 8′ advanced at 2,000 RPM, the knob on the light can be set at 8′ advance, and then when the engine is at 2,000 rpm the timing will be correct when the light flash shows the timing pointer at TDC.

Of course, there is the occasional car that runs worse when timed according to the specifications. I have had to manually advance the timing a little bit at a time until I can hear engine knock, then slightly retard the timing until the engine knock stops.

As they say, timing is everything.

Please email all inquiries to: Dave
or snail mail
32 Turkey Hill Road
Richmond VT 05477