Timing Lights and Reverse Rotation

When using a timing light with advance adjustment, do have to compensate for the direction of engine rotation?

As far as the light is concerned, 5 TDC is 5 TDC, regardless of direction of rotation. Is this correct?

-JJ

JJDebeers said:

When using a timing light with advance adjustment, do have to compensate for the direction of engine rotation?

As far as the light is concerned, 5 TDC is 5 TDC, regardless of direction of rotation. Is this correct?

-JJ

Click to expand...

First....... if the RH Reverse Rotation engine is set up correctly, the Harmonic balancer and/or timing tab will be correct for Igntion timing in the oposite direction.
Your advance will be BTDC....., not TDC, and you will be reading these markings just oposite from that of a standard LH Rotation engine.

Try to mark off the balancer, rather than relying on the digitally advancing feature of the timing light.
This way you can read the progressive advance and TA in Real Time/Real Degrees.

I don't mind the digitally advancing lights for Automotive, but Marine Ignition advance is simply too critical that it be spot on.
IMO, that is.

NOTE: Your 5* advance is BASE advance. We fire up on BASE, and we idle on BASE. After that, BASE is pretty much meaningless.
We want to also check and see what the progressive and TA (total advance) is doing.
These are the important numbers that can mean the difference between performance/no performance, and/or detonation damage.

Your OEM engine ignition specs would normally tell us what this is to be, and at which RPM it is to be Full In.
The problem is..... we have yet to confirm just what Chrysler Marine wants for this.
No one here at ME.com seems to be able to find this!

.

I assumed that 5 TDC would be interpreted as "5 degress before top dead center". I will be more explicit next time.

I'll be using the markings on the flywheel since there is no timing tab above the balancer. What is your suggestion in this case?

-JJ

I knew what you ment by 5*, I was just adding clarity that this would actually be BTDC.

My suggestion is that no one on a forum offer torque or ignition timing specs! IMO, there's simply too much margin for error via misinterpretation or miscommunication for something this important. In all honesty, people should look this up in a manual of their choice and for themselves, placing the ownus on them...., not anyone else!
No manual....., don't attempt the work!

However, if I was able to find a Chrysler Marine ignition curve graph, I'd certainly post it.

I suppose that could strobe your flywheel markings, and then plot this out in graph form and post it. We'd at least have an idea as to whether you are close or not.

.

I could do that. I could plot out the data in Microsoft Excel and generate a curve.

What do I need to do other than base timing? Just vary the RPM and measure the angle at ignition?

-JJ

With an electronic ignition, if your BASE timing is correct, what could cause your progressive timing to be off? If the mechanical tolerances inside the engine are good, then everything after BASE should follow as designed, correct?

-JJ

JJDebeers said:

I could do that. I could plot out the data in Microsoft Excel and generate a curve.

1..... What do I need to do other than base timing?

2.... Just vary the RPM and measure the angle at ignition?

Click to expand...

1.... JJ, that's about all you can do.
The rest is up to the advancing mechanism within the distributor, and personally I never allow an engine to leave here without varifying this.

2.... Yes, and at crankshaft angle!
Check at idle RPM, and perhaps at 1,000, 1,500, 2,000, 2,500, 3,000 and at 3,500 rpm.
When plotted out, this will show your progressive advance curve.

Many of the Marine curves do not include BASE advance...., but because you will be checking this dynamically, your curve will include BASE.

BASE can be removed from the curve if need be..... but typically we want to see actual numbers.