620 internal reg alternator question

[p411]

Hey guys, Can someone tell me the size / diameter of the alternator can without the mounting ears?  basically the size of the housing if measured from the rear. Reason is someone mounted a GM alternator on my L20 and its too big, its about 5.75" . I can only get soo much tension on my belt before it hits the steering box. I cant run a shorter belt bcuz the next size belt down is too short,  So i wanted to mount an internal reg nissan alternator on my 520 in hopes that the can would be smaller so I can pull the belt tighter.  maybe off if a 620 or 280? anything with an internal reg. Thanks in advance.

[datzenmike]

Alternator should be on the idler arm side not the steering box.

 

What about a slightly larger pulley?

 

The '78-'79 620 alternator is quite small and internally regulated. Down side is barely 30 amps output.

[p411]

Alternator should be on the idler arm side not the steering box.

 

What about a slightly larger pulley?

 

The '78-'79 620 alternator is quite small and internally regulated. Down side is barely 30 amps output.

Thanks Mike great idea Ill try the larger pulley I looked high and low for a smaller pulley didn't even think to look for larger :poke: ! Yes some reason they mounted the Alt on the Driver Side. :thumbup: 

[Pacific coast Datsun]

I run a 50 amp IR alt off a 81 510. Fits fine..does come close to the idler arm but dorsnt hit it. Had to run a smaller belt.

[Pacific coast Datsun]

I should add..this install is on my 74 620.

[abbylind]

Not to hijack a thread but has anyone put a 200SX alternator on a 620? Was thinking of putting one on my 77 620

TIA

[datzenmike]

It would have to be a '77 200sx to match your '77 620's external regulator.

 

The 620 is kind of limited by space. The alternators on the trucks have a tight fit above the idler arm and will rub. Smaller alternators are used. The larger diameter 50 amp car alternators... 240z/510/610/710/A10 and S10 (200sx) are a very tight fit with the lower rad hose in the way.

 

I used a 280zx lower rad hose inlet pipe to the timing cover. It moves the rad hose back slightly and gives a bit more room to swing the alternator up on a shorter belt to clear the idler arm. I also used a 720 (? I think ?) alternator to block bracket which also lifts the alternator slightly, and a shorter belt. Still you had to slip the belt on the pulley and then put the bolts in the alternator to mount it. It worked but I had to make it work and wouldn't do it again. 

[abbylind]

Thanks for the advise. I was adding new headlights to my 620 so I was looking for a higher amp alt. If I went with a newer IR alt I was planning on the rewire for the external regulator bypass

[datzenmike]

Search has dozens of threads on alternator swaps into the 620. Saturn alternator swap comes to mind.

[abbylind]

OK Mike Im doing it...got the 60 amp alt for a 77 200SX. Kept the external regulator...easy rewire. It fit perfectly and didnt hit the new idler arm. Its resting against the outlet for the lower rad hose. The block to alternator bracket is maxed out if the belt was about 1" longer I think it would work. I dont like the block to alternator being maxed though...

 

[datzenmike]

Maybe a centimeter would be better. Try a half inch longer first.

[abbylind]

Wilco...will advise..

[abbylind]

Mike

Got the alt installed. Used a belt that was 1/2" longer. Built the upper bracket from a Chevy V8 alt bracket. Fits nice and snug. Moved the lower rad hose and got good clearance...also found the lower hose is bulging by the engine inlet...time to replace. Im reading 14.5-15.3 volts on the battery terminals with the motor running. Sounds like a turbo winding up when I drive around!