Driveline vibration

[Royce]

Wish I could find an oscilloscope. Seems they have been purged from repair shops in the 90s. I found a potential issue as i am trouble shooting the ignition.. I measured voltage at the coil and got 12.7.. So naturally i think the resistor wire is missing.. Then i read up on the INTERNET and guess what, a dozen different opinions most of which sound bogus to me.. Anyway  there seems to be a disagreement on whether the reading you get, key on engine not running, is accurate if the points are open.. The theory goes that the resistor wire only drops voltage if current flows, which would be with points closed.. I missed exam on Ohms law.. What say Ye.  Oh  I just realized we have an electrical engineer in the group...Jay?

[e philpott]

you need to measure while running

[Royce]

That generated another online controversy.. The thinking goes like this..  since the current is switching on and off rapidly and the Multimeter can't keep up with the fluctuating voltage you get an inaccurate reading..I measured it running and it is 11.5 to 12V

[RustyCrankshaft]

That generated another online controversy.. The thinking goes like this..  since the current is switching on and off rapidly and the Multimeter can't keep up with the fluctuating voltage you get an inaccurate reading..I measured it running and it is 11.5 to 12V

If you have a peak hold function on your DMM you can still get a good reading. The meter is plenty fast enough to get the reading, but the display has to be dampened to a point the numbers are slow enough to be seen by eye.

They aren't as good as a true oscope, but Fluke has a pretty inexpensive "automotive" oscope/meter combo.

[GerryP]

There are a couple scope options.  A graphing multimeter, or a digital scope in either a hand-held oscilloscope or a laptop based scope, like Pico.

Ignition oscilloscopes and lab scopes in general have not gone away.  They are more critical today than in the days past when we used those huge Sun console tune up cabinets.  These days, if a sensor has a square wave output, the only way to see that is with a scope.  Most sensor issues are diagnosed with a scope.  They still use scopes for ignitions, it's just done mostly with sensor pickups rather than clip lines.

[57 lima bean]

Glad only the wallet bleed and not your knuckles with wrenching.Some good hypotheses here.Maybe the points need sharpening?Hope to see you at the Radiation Race next month.I'll buy ya a beer and brat.

[jayb]

Royce, whoever said that the points need to be closed to check the voltage at the coil is correct, with the points open there is no current flow through the coil and thus no voltage drop across the resistor wire.  Close the points and check the voltage.  Also, I don't know of any multimeter fast enough to keep up with points that are opening and closing rapidly.  The multimeter would average the voltage readings from a rapidly changing voltage, so it would show a lower voltage than batter voltage, but not the actual voltage at the coil when it is charging.  Hope that helps - Jay

[winr1]

If there is a resistor inline before coil ..... there should be ....

Voltage at + side of coil should be around 75% of battery voltage with mill not running

Same 75% of battery voltage with mill running

EDIT:

Have ya pulled all the belts and run the mill ??



Ricky.

[thatdarncat]

Wish I could find an oscilloscope. Seems they have been purged from repair shops in the 90s.

They still have an oscilloscope at BradFord’s shop, he used it to diagnose an odd problem on my race car a few years back, found it immediately with the scope. It helped immensely too, to have an experienced mechanic (BradFord) who recognized the issue as soon as he hooked up the scope. You really need to move to Minnesota Royce lol.

[57 lima bean]

Recent communications with Royce have determined that zero voltage to the coil will diminish engine vibrations considerably.

[Heo]

Recent communications with Royce have determined that zero voltage to the coil will diminish engine vibrations considerably.

 

[Royce]

Steve, You are going to drive me to put an LS in this thing.  LOL
 Ignition research has halted till my in line diode comes..  And replace the radiator which was damaged when the shop dropped the tranny to change the converter, tilted the motor and put tension on the expansion tank.. and the hipbone is connected to the thighbone......a cascade of inter related issues.. Oh and now I have a giant tranny fluid leak to boot

Kevin a much better solution would be to get BRADFORD to move to Wi with tax incentives and increased salary and more favorable politics

[Joe-JDC]

You do know that the '61s still came with Y Blocks, also?  A 390 Y Block would be very cool.  Joe-JDC

[Royce]

Joe  Don't think I have not considered a Y Block!  I looked for a long time for a 60 or 61 Starliner with a Y-block. Seems the first thing guys did was rip out the venerable 292 and stuff in a 390.  Damn Shame...  I actually have a  Frankenstein 412 inch short block in the back corner of the shop.