Verifying Timing - Engines w/o Marks

[barge]

I've got a g4x mini pnp on my R53 mini and I was wondering if there's a generally recommended way to verify ignition timing on an engine that has no crankshaft timing marks.

I'll up adding an ATI damper which at least has marks on the damper but I'd have to add some kind of pointer to the engine side to actually make it usable.

I'd think this would have come up at some point but I haven't seen any recommendations on how to do it. Or to do it right just a TDC type timing marker need to be added to the engine. Googling around doesn't show any examples of it being done.

[Brad Burnett]

Pull number 1 spark plug and rotate engine to find TDC.

Make a pointer from a piece of welding wire and attach via a bolt on front cover.  Adjust to perfection.

 

[barge]

22 minutes ago, Brad Burnett said:

Pull number 1 spark plug and rotate engine to find TDC.

Make a pointer from a piece of welding wire and attach via a bolt on front cover.  Adjust to perfection.

 

I was thinking along those lines... once I get the aftermarket crank damper on. Unfortunate that the stock engine has no capability to verify timing while running at all.

[Brad Burnett]

On 2/28/2022 at 8:53 AM, barge said:

I was thinking along those lines... once I get the aftermarket crank damper on. Unfortunate that the stock engine has no capability to verify timing while running at all.

I hate that.  Many LSx engines are the same way.  Then you get the engines that have the timing marks on the flywheel in the bellhousing. 

And with my hatred of timing lights, the engines that only have a TDC marks, make for utilization of "dialback" timing lights which require a extra electronics in the timing light.  My preference is the cheapest timing light possible.

[barge]

1 hour ago, Brad Burnett said:

I hate that.  Many LSx engines are the same way.  Then you get the engines that have the timing marks on the flywheel in the bellhousing. 

And with my hatred of timing lights, the engines that only have a TDC marks, make for utilization of "dialback" timing lights which require a extra electronics in the timing light.  My preference is the cheapest timing light possible.

When I put the ECU in originally I was kinda stuck with just trusting and hoping the base map timing was pretty close (it has been on my subaru).... but I'm going to be going in and doing a bunch of work so time to make it right.

[Brad Burnett]

The base maps for the subarus have the crank offset pretty spot on.  I would usually only have to move it at most 2deg.

 

[Thomas Barnes]

We've made a timing pointer that bolts to the sump. We get the engine to TCD and mark the crank damper. We then use a timing light to get the correct timing calibration.

The new G4X firware will definatly need to be checked.

[koracing]

A dial indicator and some method of measurement of piston height in cylinder 1 is certainly going to be required to get an accurate TDC mark.  If the engine is ok with going backward and forward you can use a piston stop and mark the damper in both locations and then split the difference for true TDC.  I've heard of but never used personally a whistle type TDC indicator.  https://www.summitracing.com/parts/sng-33650

Once you have a TDC mark, and you have a tape measure, it's certainly possible to create different timing marks at different degrees of advance.  Since the circumference measurement is diameter*pi, you can measure the diameter and calculate circumference, or wrap a flexible tape around the damper and get the circumference directly.  Adding a 10, 15, or 20 degree reference mark by taking your circumference measurement, and mulitplying by the fraction of 360° you want.  10/360=.0278 - if the damper is 7" diameter, the circumference is 22" - 22" times .0278 is 0.611".  So you could make a mark with calipers at .611" away from your TDC mark to get 10 degrees.  There are also damper tapes available for some common size dampers, or you could theoretically make your own using the method described above if you were so inclined. https://www.summitracing.com/search/part-type/timing-tape