Sweet mercy it's been a while since I've been on here! Lots of personal stuff kept me from getting going on my 67 Dart 270, but that's all been cleared up and I'm getting back to work! My 225cid engine is rebuilt and I'm purt-near ready to drop the engine and transmission into the car!

I'm upgrading the alternator to a 90amp Denso unit. Here's what I know I need to do in order to make this a safe upgrade:

- Shave the mount to accept the new alternator and line up the pulleys.
- Run two 10ga wires from alternator positive to battery positive terminal with two 50amp fuses in each one near the terminal ends.

Now, my question:

I see references to bypassing the ammeter or switching to a voltmeter. The easy and less-possibility-for-screwing-up solution, to my mind, is switching to a voltmeter. Do I still need to beef up the wiring through the firewall?

If I need to be more clear, please let me know how. Thanks, ahead of time, for your help!

This wiring method will prevent the ammeter from working correctly, so you pretty much have to run a volt meter if you want to keep an eye on your charging system. The firewall wiring connection does not need to be beefed up since you are not running full alternator current through it.

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Matt Cramer
1966 Dodge Dart turbo / EFI project

So, if I understand you correctly - once I switch to a voltmeter, I do not need to alter the wires that run through the firewall? I hook it all up as before?

The power from the alternator needs a low resistance path to the battery. This is NOT the factory wiring which passes through the bulkhead connector twice to reach the battery.

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Joshua

Correct, thank you. However, the factory wiring that runs through the bulkhead connector is my question. Does it remain disconnected from the alternator, does it get hooked up as normal and run through the new voltmeter, or do I need to install beefed-up wiring to run through the voltmeter?

The alternator and battery wires to the bulkhead connector should be spliced together on the engine side of the firewall so that the little terminals in the connector share the body load. There should be a fusible link or large fuse betwixt the battery and these bulkhead connections. Nothing runs "through" the volt meter. The volt meter is like a pressure gauge. Volt meters draw and insubstantial amount of current, but the lights, wipers, blower motor, etc draw quite a lot.

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Joshua