Alternator Bolt

70 challenger 440 can not keep alternator belt tight. Right now on the slot bracket just has a bolt with flat washer and lock washer. Can someone tell me what was original ? I would think the bolt would have a loose serrated washer. Right now I'm going have to put a a heli coil in alternator because I overtighten the bolt.

Is the upper bolt supported by spacers?

yes

Not sure about '70 E body 440's, but the ICCA 68-70 B Body Fastener Reference Manual shows a 5/16-18x0.88 SEMS Hex head bolt with a 0.75" non serrated loose washer.
A flat washer under a lockwasher defeats the whole purpose of a lock washer!!
Jim

I don't think that's correct....just my 2 Cents

Joe

Yes seems to be to short. Bolt I took out had 1" thread showing after washers and I don't think that is long enough.

Rod

Is the lower bolt loosening and sliding down the lower bracket?
if so there would be some heavy scratches in the bracket


Or is the belt stretching

Some years ago some of the Quanta resto belts were known for stretching. I don`t know if they are any better today or not. I never had a stretching problem when using a mopar belt.

That alternator bolt is correct. 7/8" long with 3/4" cap washer. LG head is another common example. If you look at the alternator there is only so much thread in the front cover. So 7/8" plenty long. If you stripped your cover you need to fix that. Cover is only thick as nut so a longer bolt does no good plus gets bolt closer to rotor.

If it is not the belt, what about the top bolt going into the head. Many time they maybe too short with only a few threads engaged. That play an important part in locking up the alternator via the sleeves. Loosening the alternator bolt without loosening that bolt and my alternator doesn't pivot.

and you can buy the correct hard ware here, littledetroitrestorations.com

^^^^^^^ agree removed many many of them thru 55 years.

Been in machine repair for 45 years and have always used flat washers with lock washers. The flat washer gives something for the lock washer to bite into. Just my 2 cents.

What is the best thread repair insert available ?