Setting up static ignition timing

November 17, 2009 by mike.cox

All engines require accurate timing if you want maximum performance from your machine.
When owner’s manuals say, measure T.D.C with a straight rod through the sparkplug hole. Make a mark on the engine corresponding to the T.D.C mark on the rod.

Then mark the rod x number of millimetres higher up the rod from T.D.C which corresponds to the firing point at full advance.
Bring the engine up towards top dead centre and when the first mark appears next to a known static mark on the engine stop and set the timing.
It’s the crudest method known for a race machine.
 
There is very few accurate ways to find top dead centre.
One method is you need a modified sparkplug that has an extension to the end.
The extension should be long enough to stop the piston well before it gets to top dead centre.
Fit the timing disc to the crankshaft so that the 0 degree mark is close to 12 o clock when the engine is very close to top dead centre.
Attach a piece of welding rod to the engine so that the end of the rod can be bent to the zero mark. It is not important yet if you are out by 10 degrees or more.
Get the engine onto the compression stroke (both valves closed).
Fit the modified sparkplug.
Slowly turn the engine over until the piston touches the sparkplug extension. But not the valve or valves.
 
Make a note of how many degrees the crank stopped from before top dead centre.
Turn the engine backwards until the piston touches the extension again.
Make a note of the number of degrees before top dead centre.
The actual top dead centre is the difference between the two readings.
For example; first reading is 30 degrees.
Second reading is 20 degrees.
Actual T.D.C is 25 degrees from either reading.
Now set the rod to this measured figure.
You now have a very accurate T.D.C.
Now you can start to get the static ignition timing close to factory specifications.