Verifying the AeroVee Secondary Ignition Timing

[Bryan Cotton]

Hi Guys,

Question: Has anyone tied their airplane down and checked the secondary ignition timing, with a timing light, as RPM was varied over a wide range? I seem to remember that there was a significant shift with RPM.

Wes

I did. No change. It is fixed timing. I didn't go to max RPM, too scary.

[Scott Todd]

That's a great picture. Its about where my lines are. We found we liked the adjustment feature. It compensated for the lines not being accurate. From adjustment, to shutdown, to changing plug wires, to re-starting, all happens in less than a minute once you get the hang of it. Last time we worked on it, we did three adjustments and the whole process was about 5 minutes. Best $30 spent on the entire project!

[Rynoth]

Thanks for the replies! That helps me understand how the timing light setup works. I do have a question as someone who has done 99.9% of my work on the plane solo... is it conceivable to setup a recording video camera focused/zoomed in on the timing mark location and do the ground run alone? And/or, has anyone taken video of the timing light test while in progress to determine whether a camera provides the same visual insight to the state of the timing via the timing light as eyeballs do?

[Bryan Cotton]

Ryan,
We had considered using the GoPro and watching it on the phone in the cockpit. Seems like it would work.

[Area 51%]

On your father's Ford, Chevy, or Dodge, the number one spark plug wire was necessarily used due to the single spark per 2 revolutions and the factory location of the timing marks on the balancer.

If you set a pointer to coincide with the #1 cylinder on our Aerovees, #3 will work just as good. 2 and 4 also play well together thanks to the wasted spark set-up. Adding one thing more, if you also highlight a flywheel tooth 180 degrees (44 teeth I think) from #1-3, you can use any wire you choose.

[Scott Todd]

You should definitely have a friend help for safety.

[Spaceman]

Howdy Gents,

What kind of RPM drop do you guys get during a run-up as you switch between the two ignitions? Mine seemed high so I got a friend to help me check the secondary timing with a timing light, and it looks right to me! However, my RPM drop seems to be about 250 on primary only, and 200 on secondary only, compared to both. Does that make sense?

Here's me checking the timing. I set the flywheel just like the picture in the manual depicts for checking the static timing, and then just made two silver sharpie marks on the left side where I could check it with the light.



Here's a quick run-up check (both, then #2 off, then both, then #1 off, then both):

[WesRagle]

Hi Chris,

Sorry, I can't answer your question but I noticed that your airspeed indication is varying with RPM. Where did you mount your pitot?

Wes

[Spaceman]

In the normal spot on the right wing... Yeah I've noticed that too, I'm interested to see how it behaves in flight haha

[XenosN42]

In the normal spot on the right wing... Yeah I've noticed that too, I'm interested to see how it behaves in flight haha

At those RPMs your airspeed should be a steady 0. As a test run the engine just as you did before but with the pitot covered.