Positive ground timing light??

[1963Turnerjohn]

12V positive ground and timing light
Bought an Innova model #5568 timing light (with display screen). Decided to call their tech guys to double check if I could use on positive ground , when I received from them a resounding No...

So has anyone used one of these timing lights on a positive ground car ? It’s hard to imagine you cannot just put red to ground and black to power - do before I return it, thought I’d check here

Thanks
John

[2cams70]

Why don't you convert your car to negative ground just during the tuning process? That's if you don't want to convert it to negative ground permanently. Pretty simple to do if it's still running a generator and little in the way of other electronic equipment. You could of course just disconnect the generator or alternator whilst you are doing the tuning.

[1963Turnerjohn]

Well , I’m hoping there is either a light made for positive ground or a way to make this specific light work. I’m kinda a period correct enthusiast and want to keep the car as made

[SENC]

I suspect the dwell fx wouldn't work, and maybe being digital electronics it might give a fault if hooked up "backwards" like my way too smart jumper battery. A more basic model should be fine, or you could probably power that one with an extra battery to make it work. I have a simple battery-powered light similar to this one - https://www.summitracing.com/parts/wmr-w80578.

[2cams70]

Well , I’m hoping there is either a light made for positive ground or a way to make this specific light work. I’m kinda a period correct enthusiast and want to keep the car as made

Like I said very simple process to run it negative ground just whilst you are doing the tuning and convert it back afterwards. Doesn't have to be a permanent conversion. Reverse the coil, disconnect the generator (if you don't want to reverse polarize it), reverse the battery, disconnect the radio, maybe disconnect the tachometer. There's no issues with the Lucas starter motor running reverse polarized. It will turn in the correct direction.

That's about it and it will run negative earth.

[1963Turnerjohn]

It’s a good idea , though I’d have to buy another Petronix Ignitor in Negative Ground , which is about same price as timing light.

If points were in use - your direction would be very convenient!

[elancoupe]

Send it back...... I used a simple analog Snap On timing light on my car for many years, when it was positive ground.

Now that the car is negative ground - it still works.

[Andy8421]

I had a quick glance at the instructions.

The supply cables and inductive pickup don't care if the car is negative or positive earth (assuming you connect them the right way round), the wrinkle will be the dwell connection - which seems to be optional as the instructions imply that it doesn't need to (and can't) be connected for cars with distributor-less ignition systems.

If you are willing to give it a try, and don't mind not having the dwell facility, then connect the supply cables - positive to ground and negative to a supply somewhere, and clip the inductive pickup to #1 plug lead.

No guarantees mind you - if you have a go it is at your own risk.........

[gjz30075]

Andy beat me to it. I think that lead with the green cover goes to the neg. side of the coil for the dwell.
Simply, just don't hook it up. All other, simpler, timing lights will have the black, red and inductive
pickup leads.

[mrfettler]

Think you could just put another battery near the car and connect the pos and neg leads to it then just clip the HT pick up lead to no1 cyl If you dont have point just leave the dwell lead to one side as not needed ?

[2cams70]

Another possibility is an old style neon timing light. They connect in series with the plug lead and will work positive or negative earth no problem. Very cheap and simple. You have to work in near darkness though because they are pretty dim!

[1963Turnerjohn]

Well after done some searching, I located a Bosch/ Actron light that works on positive ground, I need to order on line vs local. It’s Actron part # CP7539