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View Poll Results: Which would you trust?
The timing advance light? 6 54.55%
The timing pointer? 5 45.45%
Voters: 11. You may not vote on this poll

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Old 03-04-2004, 07:48 PM
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Trust the timing light or the timing pointer?

I am getting different readings from my timing light and my timing pointer. Right now I am trusting that my advance analyzing timing light set to zero, is accurate when reading at the pointer. The timing pointer has TDC and increments of 2o stamped into it up to 16o advance.

When I turn the dial on the timing light to the advance I want, the balancer mark should be at zero. When I turn the dial back to zero on the timing light it should be the correct amount of degrees at the pointer.

Well, this isn't the case. I have been trusting the pointer up until now. The timing light advance dial is indicating that my initial advance is really two degrees more than the pointer says.

Should I trust the dial in the timing light, or the pointer?

I have tried using another timing light, but it only has a zero reading. No advance. It verified that zero is zero on both timing guns. It is what is after zero that I am concerned about.

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Old 03-05-2004, 03:50 AM
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I'd trust the pointer.

I prefer to use a degreed balancer or timing tape and leave the timing light set at '0'.

I have checked my timing light (adjustable) against the pointer and mine is accurate. However, since the adjustable timing light can malfunction electrically internally, I go by the pointer reading.
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Old 03-05-2004, 05:29 AM
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I agree, you can double check your 0 setting with 2 or more lights, but as far as an advancing light, I would go with the pointer also!
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Old 03-05-2004, 07:25 AM
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After trusting pointers for years I bought myself a Snap-On timing light and calibrated the pointers TDC position with the piston stop method. When I checked it the timing tabs markings were consistently off 4 degrees. Those little stamped vernier markings on the pointer are not to be trusted, they are far from precision devices.

I trust the light when I know where TDC is and as a consequence only adjust the pointer to TDC and never use it for anything else. With the advancing light who needs timing tape? I aslo adjust the tab so it just grazes the balancer wheel, it helps reduce parallax error when looking from the top.

I trust the light.
“She may not look like much, but she's got it where it counts, kid. I've made a lot of special modifications myself.”

— Han Solo
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Old 03-05-2004, 07:47 AM Moderator

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If you have a msd box on the car you will not get a repeat reading with a dial back light. If i remember right There nomenclature even states that.

If you know for sure that the mark at tdc is right on and you have the proper location degreed on the balancer there is know way that can ever change.

As far as the lights being correct at zero. If you compared 2 of them and got the same reading at zero then the odds are pretty good that your right.

I checked on time at home. I have a $350 snap-on, a sears dial back,and a el-cheepo sears. They were all the same at the zero mark, but in the advance there was some difference. This was on a car with the msd box.

It' real easy to put your own marks on the balancer. Just take the diameter of the balancer x Pi (3.1416) then divide by 360. This will give you the amount in thousand of an inch for 1 degree. Then times that answer by the number of degrees you want. I use a 6" flexible scale and mark the balancer.

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Old 03-05-2004, 09:03 AM
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The pointer is one of those stock stamped types.

I checked that RDC was accurate with the heads off. I know for sure that TDC on the pointer is actually TDC on cylinder #1.

I don't have an MSD box etc. The only thing other than stock in the ignition is a Mallory Unilite distributor and an Accel Super coil.

Can a potentiometer variably malfunction? I mean, I doubt the voltage can disproportionally change as the knob is turned, right?

Last edited by lluciano77; 03-05-2004 at 11:31 AM.
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Old 03-06-2004, 01:35 AM
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Yes they can malfunction. Volume controls & throttle position sensors are basically the same thing, & they go bad regularly. I've heard way too much bad stuff about dial-back lights to ever trust one. It's hard to screw up timing tape or a dot of whiteout 1/10 of the way around the balancer from the zero mark.
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