Kujokku Posted May 13, 2019 Report Share Posted May 13, 2019 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 Quote Link to comment
datzenmike Posted May 14, 2019 Report Share Posted May 14, 2019 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. Conversion 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. Quote Link to comment
Kujokku Posted May 14, 2019 Author Report Share Posted May 14, 2019 Thanks Mike, I will do that Quote Link to comment
banzai510(hainz) Posted May 14, 2019 Report Share Posted May 14, 2019 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 Quote Link to comment
Kujokku Posted June 17, 2019 Author Report Share Posted June 17, 2019 I connected the wires as shown, I run mikuni carbs so the electric choke is not an issue. The charging system works fine, however the battery was dead after not using the truck for a couple of days. I took a meter and checked things, and with the key off the B connection (red/white wire) on the alt was reading battery voltage and the yellow wire on the 2 prong plug in for the alt is also reading battery voltage, all with the key off. I am assuming this is the drain, how I can I solve this? Quote Link to comment
datzenmike Posted June 18, 2019 Report Share Posted June 18, 2019 On 5/13/2019 at 7:39 PM, datzenmike said: 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) Covered this already... Remove the choke heater relay!!! Or unplug it. It's still on. Even though the heater is gone the coil inside the relay will take about 3 days to drain the battery. Quote Link to comment
Kujokku Posted June 18, 2019 Author Report Share Posted June 18, 2019 Sorry for missing that, where is the location of choke heater relay on the 77 620? Quote Link to comment
datzenmike Posted June 18, 2019 Report Share Posted June 18, 2019 Just kiddin', it's an easy fix. If there's a black plastic box on passenger side inner fender to the rear of the alternator voltage regulator, covering some relays, it's one of those. It will have the following wires to it... White/Blue (stripe) Blue Black Yellow 1 Quote Link to comment
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