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914World.com _ 914World Garage _ Plotting Advance Curves

Posted by: bd1308 Sep 13 2006, 10:49 PM

So I'm thinking aloud here....

You grab a motor and spin it without load and measure its rpms. you're also able to measure the current draw on that motor at any point.

Now take a dizzy and attach it to that motor.

you already have the unloaded values for the motor, and if the motor is weak enough, the dizzy might have enough torque to show up on the motor as increased current usage to turn motor at same speed.

OK, now there is a point where the centrifugal advance doesnt kick in, and those values are listed on the PP forum.

By plotting RPM vs. current reqd to turn dizzy at RPM, one should be able to plot the advance curve of the dizzy, correct?

b

Posted by: bondo Sep 13 2006, 11:01 PM

No.

You need an oscilloscope.

Posted by: bd1308 Sep 13 2006, 11:15 PM

oscilloscope measuring what?

Posted by: eric914 Sep 14 2006, 07:05 AM

I don't have a distributor in front of me to confirm this but I think if you can plot plug 1 against one of the fuel injector contacts you should be able to see the advance. I think the fuel injector contacts are fixed to the input shaft so you can use one of them as a reference signal. Plug one will then vary in relation to it as RPM changes. You could also activate the vacuum advance to see how it responds.

Posted by: bd1308 Sep 14 2006, 07:07 AM

I have teh L-jet versions of these, so I dont have that reference to map against.

maybe i could design 'points' that are fixed to the motor shaft, and then measuring delta x, where x is the two point sets in my test