How to - Hillbilly Timing Tape

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Hold on....a circumference is measured in degrees. 3" or 30", 10 degrees is gonna be 10 degrees on a DB timing light.
You know I thought about it & you're right, a quarter turn (noon to 3 o'clock for instance) is gonna be/read the same on a wristwatch as in a big wall clock just a different diameter. I stand corrected, thank you!
 
.6875x16×3=33 4.4×15÷2.5÷0.8=33

= WTF I don't care

This thread got polluted long ago. Simple method to do things. Want to do it different, have at it. @RustyRatRod

Much the same as the accuracy of the MSD bushings, one being .002 larger than another. You aren't going to get an engine timed to a level of precision using manual inputs where the margin for error exceeds your manufacturing tolerances. If you can pick up on .01 degree difference with a light.. you're darn good!
 
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@4spdragtop

Part of the reason I only do two marks is you don't have to figure out which one is which if you place 6-8 marks on the balancer. If you where to make the marks different lengths, all across for 10* levels and half for 5* to differentiate, that would be good.

The only time math comes into play is when you are actually timing the engine. the 15 mark will allow for timing from 5-25, the 30 mark from 20-40.
 
Lol hey rob I was only posting the math to show more than 12 ways to fillet a fish or skin a cat. Helping convalute things lol!
 
Lol hey rob I was only posting the math to show more than 12 ways to fillet a fish or skin a cat. Helping convalute things lol!


Tuna, Halibut, trout all filet a bit different... you needed a x squared exponent in your math equation to account for that LOL @4spdragtop
 
A V8 fires every 90 crank degrees. The time width between pulses varies with RPM. Higher RPM the shorter time between events. A dial back is a way to subdivide time, divide by 90, each division is a degree. Most use a pot to select count of divisions, pots suck, for accuracy.

4 cylinders fire 180d, /6 at 120d so a dial back needs to know that. Nothing to do with balancer diameter, just time delay. An example for V8, 3000 RPM width is 5ms, half of that is 2.5ms, delay that amount for light would be 45 degree setback.
I dont think it even needs to know if its a 6, 5 or a 1 as you are clipping onto the #1 plug wire, not the coil wire. I knew it had to do with measuring the pulse width , just didnt know how they slowed it down ('cause you cant speed it up) , variable capacitor charge time?
 
I was totally wrong! Trying to reply, while baby sitting an active 3 yr old.
#1 fires every 2 engine revolutions. That time divided by 720, times the desired set back. Same formula. Doing that with uC is easy, analog means sounds iffy.
Never used or owned a set backing light.

Systems I build and use measure RPM based on reference sensors, calculate ignition timing and coil charge for every ignition event. Timing is available in car, and logged for analysis. I only use a timing light to verify static timing. My sensors trigger at zero speed, so not errors related to variable reluctance triggers.
 
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