Setting Timing with a Petronix System

[JSpears]

How do you set the timing when there is a Petronix system? Can I just put the Timing Light on the first spark plug and look for TDC at 4 degrees off? Also, I noticed that the light does not always flicker, at times it will skip. Does that mean I have a miss to the spark plug #1? New rotor, wires and cap will fix that?

 

[DrEntropy]

Yup, timing is timing. But I thought there was more lead than 4° on the TRs.

Don't believe the light if it's an induction unit. Some are better than others. You ~may~ have a wire problem but getting the timing right should come before looking for more trouble. :wink:

 

[poolboy]

Yeah, I think that 4 degrees is some kind of a static setting used just to get an engine started after an overhaul.
Turn the distributor clockwise until the engine sounds good; then adjust the idle down to 850-900. If this is a TR6 there's no way to over advance as long as the tach cable is attached and limiting the clockwise rotation of the dizzy.
But you'd be a whole lot better of using a Vacuum Gauge instead of a timing light.
https://automotivemileposts.com/garage/v2n8.html

 

[TR3driver]

But I thought there was more lead than 4° on the TRs.

Nope, that's the official 'static' figure for the TR2-3. The reason it's so low is because the centrifugal advance curve (for the original distributor) starts down below idle rpm. My guess is that the combination made the engine less likely to kick back while hand cranking.

But for timing with a light, I'd use something more like 8 degrees.

And then either way, back it up with a road test. Advance the spark until you can just barely force the engine to knock (by lugging it when it's fully warmed up). Then I like to back off one or two degrees, just to be sure.

 

[JSpears]

This is a TR3. Thanks for the advice.