70 road runner putting out 17 volts,and making the battery sizzle!!I just put a new voltage regulator on it today and still 17 volts,when you turn headlights on its still 17 volts.Any ideas?Thanks

Sounds like a short in the alternator or possibly a wiring SNAFU with the voltage regulator wiring. Was it acting OK before?

An easy inexpensive step is to take the alternator to an autoparts store with tester (Autozone ect.) or an auto electrical shop for a test.

Is the regulator painted? scrape the paint off the back of the mounting lugs where it meets the mount. It may not be grounding

This is a new problem,when we put the 505 in it,it had the original engine harness,well i took that harness out and built my own that plugged in the bulk head.We put msd on it so i was trying to make the harness nicer.Also the Alt seems to be magnetized.Im lost.

It's all metal to metal

Something is keeping the field at over 14 volts to get that kind of voltage out of it. Check to make sure the wire hooked to the field connection on the alternator is hooked to the field output of the regulator.
The only thing holding down the voltage is the battery and it is in danger of overheating and exploding. Be careful.
Craig

unhook your field wires see if it stops charging, you made the harness id you mess up a field leg? sounds like its full fielding also unplug the regulator and see if it still does it if so its in the wiring id bet!

On back af my alt there is two feild terminals and a battery lug.I've swaped the two feild wires but no difference in output

On the battery post on Alt?

2 field terminal alt & flat later style VR I'm assunming. Take the female connectors off the 2 alt brushes & take out the brushes & see if anything is grounding & everything looks kosher inside there. Take off the connector to the VR and leave off both female alt field connectors & starting from scratch with several jumper wires run 12V from the batt positive to one (either one)of the male alt field terminals on the alt AND to the top terminal on the VR (w the triangle "up" like a pyramid)(some are mounted upside down). A jumper from the other remaining male alt field terminal to the other VR terminal (the one on the right w the pyramid facing "up". You've checked for sure that the VR is grounded. Run it at a fast idle & if still 17V I'd suspect the VR. Holler back when you find out what it is.

Which alternator / regulator setup?
If it is the newer two field wire setup, just disconnect the voltage regulator. If the voltage is still 17 volts, there is a short to ground in the field wiring that goes to the regulator, so disconnect that wire at the alternator, and if it is still overcharging, it is shorting inside the alternator (check the brushes and holders to make sure the holder is not broken or melted.)

If the overcharging goes away after disconnecting the regulator, make sure the regulator is getting a good +12v source when the key is on, if it is, the regulator is bad (shorted internally to ground.)

If the car is using the older alternator with the single field wire connection, the regulator may be bad or the field wire connection is wired wrong (not going through the regulator.)

When i unplug the regulator voltage drops to 12volts,I do have the two feild wires.

If the field wires are the original blue and green, the green wire is probably grounded between the alternator and the regulator.....try disconnecting only the green wire from the alternator.