alternator bracket bolt size

[ksurfer2]

OK, this seemed like it would be a easy job, replace the alternator on my 440. Picked up a replacement last night from Napa, started install after lunch today, figure it would be an hour job, tops. Everything went on fine until I attempted to install the tension bracket. The 5/16 X 18 bolt that was in the alternator that I took off was a smidge too small. I tried a different bolt (same size), same issue. I brought the alternator back to Napa thinking the holes may have been stripped and swapped it out for a different one. New alternator, same problem. Tried a metric bolt that was a teeny bit bigger, still not big enough to tighten properly. Next size bigger bolt in both standard and metric are too big. Before I helicoil, is there a special bolt that I should be using? Nothing came with the alternator.

 

[beanhead]

Soft aluminum housing. My 'Napa' replacement alternator stripped as well, before I got the bolt close to tight. Drilled and tapped it to 3/8 no problem..I tightened the top bolt real good and then went reeal slow on that bottom bolt.

 

[PurpleBeeper]

Poor quality manufacturing. There is no "special bolt". Guessing metric was a good idea though.

 

[5.7 hemi]

Put a heli-coil in it and never worry about it again.

 

[ksurfer2]

Put a heli-coil in it and never worry about it again.

Yup, that is what I did. Problem solved. Just surprised me that both tension bracket holes on two different alternators were f-ed up.