Timing light questions

[bgbmxer]

Got my car tore apart for a blown head gasket. Gonna check the timing on the car. Forget the procedure but I'm pretty sure is to disconnect the water temp sensor to set timing. Anyways I have a digital advance timing light from craftsman. When using this thing I'm assuming I set the digital read out to 12 degrees and it should show zero on the trans. Is this correct? Lost the directions and can't find them on the net either.

[2.216VTurbo]

Tough to check it all tore apart, I hope you mean it's back together now;) You have it pretty much right, disconnect CTS, if all your marks are correct, set the distributor so the flat front edge is pretty much in line with the center line of the crank or back about 5 degrees, that will get you close. But yeah, adjust the timing on the light until the TDC mark moves to the first line, that's zero. the reading on the light will be you timing, adjust until you see 12 or whatever you want to set it to. I like to tighten the 13mm holddown nut snug so distrib won't turn then adjust it by tapping it with a hammer the direction you want it to move. It's easy to make incremental adjustments that way and you don't burn you hand on hot parts:thumb:

[bgbmxer]

Tough to check it all tore apart, I hope you mean it's back together now;) You have it pretty much right, disconnect CTS, if all your marks are correct, set the distributor so the flat front edge is pretty much in line with the center line of the crank or back about 5 degrees, that will get you close. But yeah, adjust the timing on the light until the TDC mark moves to the first line, that's zero. the reading on the light will be you timing, adjust until you see 12 or whatever you want to set it to. I like to tighten the 13mm holddown nut snug so distrib won't turn then adjust it by tapping it with a hammer the direction you want it to move. It's easy to make incremental adjustments that way and you don't burn you hand on hot parts:thumb:

Once I do the initial fireup before putting all the airbox and hoses. Head still at the machine shop. 12 is stock correct? Mine it's all digital so I was thinking I just put 12 in and adjust till its at zero.

[johnl]

Please excuse my ignorance but I don't get it.

Why is it better to read 0 on the flywheel and 12 on the light, as opposed to 12 on the flywheel and 0 on the light?

[2.216VTurbo]

Please excuse my ignorance but I don't get it.

Why is it better to read 0 on the flywheel and 12 on the light, as opposed to 12 on the flywheel and 0 on the light?

Because, you twist the knob on the timing light till you read 0 on the flywheel, then take your reading off the knob/display. You could be at 8 or 20 or 50billion... IMO its easier to make adjustments to the distrib that way. it's the same net effect so really it doesn't matter. You could run an experiment and try it both ways to see which suits you.:thumb:

[bgbmxer]

Mine is digital so I'd put in what I want the timing to be say 12 and then turn it till it reads zero on the flywheel if I'm doing it correctly? lol. Apparently it's more accurate. I honestly have no clue either way

[johnl]

So . . . don't I have to worry about the accuracy of the knob?

I got one with a knob as a gift and the knob has insufficient friction/no detents so I'm always worried that my zero changed when I set it down.

What if, when it says 0* to mean 12* on the flywheel, it's really 2* because the pot under the knob is mis-calibrated?

Wait . . . . maybe they are a quick way, without doing subtraction, to determine how many degrees of advance from static you have?

[BIGBRUDDA]

Please excuse my ignorance but I don't get it.

Why is it better to read 0 on the flywheel and 12 on the light, as opposed to 12 on the flywheel and 0 on the light?

The old method sets the timing as close as a wobbly dizzy will get anyway.
The new fangled "digital read out" method allows you to play with your new digi-toy.:rockon:

[2.216VTurbo]

I think my knob style is an older chrome(high end stuff;)) Craftsman model. I wondered about it's accuracy too so I checked against Duncan's Snap On and they were dead nutz on with eachother. Now I supposed they could BOTH be way off the same amount:p