I just installed a new 78 amp alt, voltage regulator and ran a second 10 ga power wire from the alt to the starter relay on my 1968 plymouth valiant 225 /6. I replaced the missing 14 ga fussable link to the bulk head, installed a 14 ga fussable link to the second power wire, and cleaned the bulk head. the VR is grounded. Im running a HEI. With it just running voltage to the battery is between 14.7 and 15.7. With everything on blower, lights, stero etc the voltage at the battery gets up to 16. I read that anything over 15 is dissaster waiting to happen. Is the VR at fault? Battery cables are new.

The voltage regulator reference is the difference in voltage between it's ground and the B+ input from the ignition switch. When you turn on all those loads on the far side of the bulkhead connector the voltage to the regulator from the ignition switch drops so the regulator increases the alternator output to compensate. You want the alternator's output and the regulator's input to both be electrically close (low resistance) to the load. The way the car was originally wired the alternator output, the car's loads and voltage regulator input were all on the far side of the bulkhead connector. With the small resistance you've created between the battery alternator (10 Awg) and a larger resistance to the load (14 Awg) you have created an imbalance. Either bypass the bulkhead connector and bring the voltage to the loads up so the regulator works properly or move the regulator's input to the battery (use a relay activated by the regulator's existing input wire) and suffer the voltage drop to the loads through the bulkhead connector.

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Joshua

I talked to a buddy of mine in town and he said first off check the voltage from the ign switch to the VR and sure enough its at 11.85 while the batt at 12.68 so it looks like its either the swich or the wire off the switch.

I already knew you had a voltage drop to the regulator, but I disagree on why. Get out your wiring diagram and follow the power flow (which because of the alternator output rewiring now starts at the battery and moves to the passenger compartment) and measure the voltage at each junction. You know the voltage at the battery, now measure voltage at the engine side of the bulkhead connector, the passenger's side of the bulkhead connector, both sides of the fuse(s), both sides of the ignition switch and so on until you've reached the regulator. There is no sense in fixing a problem with an ignition switch that doesn't exist. Find the biggest voltage drop and fix it first. I believe that under high accessory load you'll find the largest voltage drop at the bulkhead connector.

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Joshua

I plan to check voltage at all contections. I was just stating what ive tested so far. It turned nasty out with 30 mph winds and looks like this weekend its going to be a high of 28. But now I know where to look. thx