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77 620 conversion to internally regulated alternator

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I have a 77 620 and I want to go to an IR alt. I've read some posts but I would like to have some specific directions for a 77 620. The alternator  I will be using is one for 720 z24, Thanks Neil

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The 720 alternator will be a tight fit because it's physically larger than the 620 one. There's not much room to fit a larger alternator and swing it away from the block to tension the belt because it hits the top of the idler arm. I had to hold the alternator and put the belt on first then put the block mount bolts in.


A '78 or '79 620 alternator will fit and is internally regulated but only 35-38 amp.




Remove the external regulator and cut the plug off leaving the wires as long as possible. Ther are two pairs or wires to join... White/Black stripe to White/Red stripe, and White to Yellow. Slip some heat shrink tubing on then twist and solder together. Slide the heat shrink tubing on and shrink it. You can now pull out any unused wires from the plug. Now connect this plug to the harness.

This is for a 710 but the wiring is the same.



Unfortunately this will cause the automatic choke heater relay coil to be ON at all times even when the ignition is off, and this will drain the battery in a weekend. Unplug the choke heater relay. (you can remove it if you want) For the choke heater to work on the carburetor a new voltage supply must be used as the relay is now disconnected. The simplest thing is to join the Blue choke heater wire to the Red idle cut solenoid wire right there on the carburetor. It's on (12v) only with the ignition and perfect for this.



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Just buy a New Power select from Rockauto.com.

I got a Power select and its been good for a year now which is a record on any of the last rebuilt alts I have gotten.

Unfortunatly size is a issue and I went back to the stock size

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