[VetteVet]

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Originally Posted by jarrodblake

Thank you, I did not know they were for the amp gauge that is good to know. I am going to be doing the 76+ volt gauge conversion to my cluster as the dodge alternator is around a 120 amps. From what I have read the stock amp gauge will not support 100+ amps and could burn up the gauge or start a fire.

I think you might be thinking of the old style amp meter which had all the current in the system flowing through it. They were set up to read 0---30---60 amps, which would have created problems if a 100 amp plus alternator were wired that way. The newer style ammeter does not flow but a few milli-amps of current through it, and instead it reads voltage potential between the alternator and the battery to measure charge and discharge.
There are hundreds of post 62 trucks that are using SI and CS style alternators with the OEM ammeters out there and they are not having problems with them.

If you wanted to keep the OEM battery gauge you would have to wire the charging system similar to the original or it wouldn't work. There is a lot of mis- information out there on wiring alternators the wrong way for the most efficiency even thought they will charge.




Yes I have read most people use it to run a HEI, I need a switched 12v power wire for my sensing wire for the alternator. I figure it would be the best wire to use as it would best represent load on the fuse box as in the fuse box it is a 12 gauge wire and it has nothing else on the circuit and would show the load on the fuse box as a whole. I was wondering if I should fuse it. But after more reading it needs to be unfused as if the fuse where to blow it would cause the alternator to send full power to try and make up for the loss of the sensing wire.

Your sensing wire for the alternator, I'm assuming it works the same as the GM styles, needs to be wired to the main circuit junction, where it can read the voltage drops in the truck circuit loads. With the GM internal regulated alternators it is wired full time hot," with no resistance", but I can't say how yours should be with the converted regulator. The wire for the HEI can be the same wire that was used for the OEM coil and points distributor, but you will not have a resistance in it. The HEI distributor needs a full 12 volts to run correctly. DjmLambert has an excellent thread complete with Pictures on using this method. It retains the stock look and does not use a spot in the fuse box as in the IGN Unfused. port.
http://67-72chevytrucks.com/vboard/s...d.php?t=708975

There was no fuse in the original schematic and the debate goes on on whether one is needed. A 12 gauge wire should be used from the firewall to the distributor.



I am however considering using it as a switched power source to power the relay box. I don't know how many amps are needed to switch a relay on, but from what I have read I can use as little as a 4 amp fuse. So I don't think it would affect the sensing wire enough to matter?

It would not have a problem switching on the relays as they only require a few milliamps of current and 8.5 volts would be plenty. BE sure to fuse the no. 30 side of the relays (battery and alternator power side) and connect The sensing wire from the alternator to the main relay on the no.87 terminal so the alternator can read all the voltage drops there from the other relays.
You realize that you are going to have a very large relay for that function. See expensive and it could leave you stranded if it fails.

Some relays need to be close to their loads for best efficiency, cooling fans and headlights for instance, so take that into consideration.

What does the Cummings swap involve? are we talking Diesel with no ignition except glow plugs, high pressure fuel pump, mechanical injectors ?