720 alternator on a 620?

[JDMClassic]

Hello ratsun family!

 

I was at a junk yard here in San Diego and I was wondering and I spotted a 720 with the alternator still in tact. I was wondering if the alternator from a 720 can fit and work on a 620? Tried researching and nothing can up. The junk yard closed while I was trying to take it out.

 

The alternator looks a little different than the one I have on my 620. I should of took a picture or it! I'll be sure to come back tomorrow.

[laotsu]

what year 720, more to the point what engine was in the 720?

[datzenmike]

A 720 alternator is internally regulated and electrically will only work on a '78 and '79 620 that is wired for them. The '72-'77 620 are externally regulated but can easily be converted for use with an internal regulated alternator. The 620 is 35/38 amps. The 720 is at least 50 and optional 60 amps.

 

It's larger and does not clear the 620's idler arm very well. I got one to fit 15 years ago by using a 280z lower rad inlet, it sweeps back more and moves the rad hose away from the top of the alternator. I also used the 720 mount to the engine. I think it lifts the alternator up slightly away from the idler arm. I used a shorter belt. Still had to mount the belt on the pulley first and then bolt it on. It worked.... barely