440 Alternator

Posted By: aar1

440 Alternator - 05/04/13 12:19 AM

1970 Cuda, 440 auto, A/C, 4-bbl.... if the car is running, should it stay running if you disconnect the battery? My car dies when I try it and the alternator supposedly checks out fine. Thoughts? Thanks!!

Posted By: RapidRobert

Re: 440 Alternator - 05/04/13 12:27 AM

Quote:

Thoughts?

Yes if the alt is putting out it would say running but it ain't recommended to check it that way as is stresses the alt (I believe). Since the alt checked out Ok I'd check the field circuit/connections for continuity/power & the reg also as needed. Need switched 12V to one field (blue wire) then continuity in/thru/out the other brush assy then the green wire to the reg & the reg grounds it as needed thru the case to ground.

Posted By: DaytonaTurbo

Re: 440 Alternator - 05/04/13 12:33 AM

Yup should run. If it's not, check the voltage regulator and follow the wires. May just be a broken wire somewhere.

Posted By: ahy

Re: 440 Alternator - 05/04/13 01:20 AM

A better (and simple) test of the charging system is to fast idle the engine and check voltage at the battery. It should be over 13V and best is 13.5 to 14.3 or so. If its under 13 volts the charging system is not working properly.

At slow idle voltage may drop as alternator output drops way off at low revs.

With low idle output of the standard alternator, the pull off the cable test may give false results... plus its really hard on any electronics like the ignition module.