'71 521 alternator issue

[Blknight692]

First off, let me say I love this forum and I love seeing everything that people are doing to their Datsuns.

Now on to my issue. My dad picked me up a 1971 521 pickup. Pretty clean with some small mods, but that can wait till later. My issue is with the alternator. When it sits there at idle, sometimes the volts drop below 11 and when I try to rev the motor the belt squeels. Usually this rights itself, but if I have anything on, ie lights, wipers or even the brake lights, it will keep squeeling untill I shut all power stuff off.

I looked into the belt, it was tight and clean. Took a look under the hood when it was acting up and noticed that under load the alternator bracket pulled forward making the belt loose. I tried to tighen the bracket and found that I am missing 1 of the bolts that mounts the lower bracket to the block. Anybody know what size and length these are? I really son't want to pull the other bolt to measure unless I have to.

Any info would be great.

[banzai510(hainz)]

I think its a M8x1.25

 

l16 use the smaller bolts but beware this is proplemmatic with the early L motors. Those bolt can shear off and are stuck in there. or maybe just worked it way out.

 

My 521 alternator always gets loose.

 

I eventuall took my lower alt mount to a machine shop and drilled it out to a 3/8 bolt and nut. later 50amper can use a 3/8 hole but early 521/510 L16s use the smaller holes thru the alternator.

 

 

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