Technical Buzzz-Box

Picked this up at an auction recently. I did a little research and found out that it is for A&P aviation vocational school. It came in kit form and was assembled under the guidance of an instructor. The student was allowed to keep it. Looks like they are still being made but only instructors/schools are allowed to purchase. Just thought it was pretty cool....... maybe put a magneto in the dragster.

 

I have had this one for over 30 years, now that I am getting back into racing, I am going to contact Tom Cirello, and see if he can repair it for me. They are very handy for initial startup, but I always check the timing with a light, after the engine is running. Great find you have there !

 

Interesting advice from Don Zig on the use of timing lights with maggies:

http://www.donzig.com/never.html

"Never rely totally on your timing light as your sole source for timing your motor. Timing lights are typically D.C. and magnetos generate A.C. They also emit E.M.I. (Electro Magnetic Interference). In general, timing lights with mags are one (1) degree late for every 1000 RPM of engine speed. For best results, use a timing buzzer. We sell them and you can see one at the bottom of our products page."

I don't fully understand electrical sorcery, but I wonder if someone can explain simply why the AC/DC difference makes the timing light late?

Cheers,
Harv

 

Fun tool. On a fixed mag you set the timing number you wanted on the crank to the pointer and turn the mag until it buzzed. Pointing close to # 1 of course, then as Marty said we did check with a light but it was not necessary. 37 degrees with 80% in a 12 port GMC got me into the 200 mph Club in 2003...

 

We used something like that to time snowmobiles back in the day.

 

Interesting info, I always thought, with the engine running, any slack between the ignition and the crankshaft, via timing chain or gears would be taken up. But what do I know, never considered the difference between AC and DC. Thanks.

 

Yup, I built one and still have it in my toolbox. Fun little soldering/circuitry reading project that gave you a tool to use too. Since there's two mags on an airplane, that box lets you time both of them together for final installation. Often, one mag will fire a given number of degrees later than the first to ensure complete combustion, and the buzz box gives the mechanic an auditory and visual signal for when each mag fires individually. Used in conjunction with a degree wheel, it is one of the most routine inspection operations an A&P will do.