Discussion in 'Engine Combos and Dynometer Database' started by Indycars, Nov 3, 2010.
love the posted picture quality
Ideally you want to check the Secondary KV pattern.
Super imposed pattern.
Actual Dwell time per cylinders all 8.
Ignition firing time.
Have my Snap On CRT Counsler Digital Ignition Storage Oscilloscope.
It was about $10,000 new .
Bought it from a Friend that closed down his Auto shop.
Still paid good money to make it mine.
$600 back 2001.
Some checks can be made with a standard CRT oscilloscope.
One mistake though and it will blow up from the High Kv secondary ignition voltage.
There is also coil saturation time too.
We are in an era of disposable everything.
It's remove and replace today.
I am one of the last mechanics to learn all electronic ignition fundementals.
Points & Mags also.
If you found no vacuum leaks at all then install the ebay distributor you have from testing back 1-1/2 years ago.
See if it hits clean on all 8 cylinders again.
My ignition timing is stable now compared to the video I took on Feb 20, 2016. Shown below.
The MSD module has changed, I read on YouTube that someone had the same problem with stability
and I had changed it after the video. So I can't say for sure if that cured the problem or the change below.
This winter I changed from a cheap Professional Products damper PN#: 8002 to a Fluidampr 62260D 6-1/4" OD Gold Harmonic Damper.
Below you can see how the ignition timing has stabilized. At about 7 seconds it will clear up, look for the black dot at 36°.
The 2nd video I can not see your black timing mark.
I use a white paint stick paint pen to mark TDC.
I have a Pontiac Egg Shell Blue paint stick pen that also shows up well with a Xeon flash strobe light.
Did you find a vacuum leak or not Rick ?
I won't have time till this weekend.
Have to make a video again.
Show how my Snap On Counsler Ignition Oscilloscope works.
Connect to my 1987 Corvette.
It also works on my Vertex Magnetos.
Spin test a Chevy & Pontiac V8 Mags in my SUN Distributor machine.
Absolute Best way to test for unusual ignition problems.
I made another video of the ignition timing stability since the last one was blurry. But first the
video with instability in post #2929 .....
In the next video I did not disconnect the vacuum advance, so the actually timing is different,
but the stability is solid.
The only things that I can remember changing is the harmonic balancer and the addition of the
valve stud girdle. Looks like the harmonic balancer made the difference, don't see how the stud
girdle could make that much of a change.
I think a stud girdle would have an affect on timing stability. I think it keeps the valve timing more stable, so it would indirectly affect the ignition timing.
What is your initial timing? Looks like in the first video its around 14-15!
I think it more about 12°.
Ok, but how does the stud girdle affect the ignition timing. I'm trying to make sense of this in a scientific way.
How this could be? It make no sense to me from logical point. The distributors connection is the camshaft and than via timing chain to the crankshaft, this would be the only parts for tolerance issues on the mechanical side (I leave the distributor internal parts aside). The stud girdle stabilized the rocker arm stud and rocker arm, ok the rocker arm has contact to the camshaft via lifter and pushrod but if there is "flexing or whobbeling" how this would have a effect on the teeth on the camshaft to distributor?
I don't think that the camshaft is "shaking" or so when the stud girdle is not installed, it would have an effect to the rocker arms and then to the valves. I think the lifter would work as an "damper" in this situation, except if it is a mechanical lifter.
I hope you can understand what I'm trying to write, sometimes it is not easy to translate my german in english words when it goes to technical stuff.
You can only Run 13.5 ET 1/4 mile at the Track with the T-bucket NHRA Rules.
Need a Full Rollcage to Run Faster.
Ready to run and see if you can hit 13.5 ET.
Could cam end play be a source? Seems like it would change rotor position.
Made sense to me. I think what you are saying is the effects of the stud girdle are too far
removed to make a difference in the ignition timing.
End play would certainly make a difference in the timing, but the end play did not change. So
that could not be the reason for the timing becoming more stable.
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