Alternator belts - how good does the alternator alignment need to be?

Could not find the alt brackets for my 65 Fury Cop car with a 383 so I am making them. I have having a very hard time getting a good belt alignment.

On this particular setup (Leece Neville), the alternator sits on top of the motor. It is a 2 belt setup with an idler. The belt is a long 7590 and the center to center on the alt pulley to idler pulley is 18 inches and idler to crank pulley is 12 inches.

What would you think the maximum misalignment I can get away with?

Picture of an original setup.

I dont have a dimention but I would lay a laser pointer or a piece of tubing in a pulley groove to see what you see for misalignment

I have used a straight edge and I kinda know what I have. Don't necessarily like it.

Buddy gave me a laser but it won't work on this v belt.

Go with your gut, it needs shimming. As you know go with the shortest belt setup you can make work & on a side note there is something about pros/cons of belts ribbed on bottom or top, not my area just a FYI.

Wow, I've never seen that long of a set-up on a Mopar. The alignment is very important for belt and component bearing life, but also to keep the belts on the pulleys at higher engine speeds. You also want to maximize belt wrap on the pulleys.

I'm of the mindset that anything different than perfect alignment is less than ideal. My Mopars have never been belt throwers though, and I've run them at much less than ideally lined up back in the day.

These days, I get them straight as I can by visually aiming down the pulleys along the length of the belts. They make pulley spacers, and you can get creative with your bracket mounting. Be sure to minimize any bracket deflection while you are at it.

I have heard 1/8" guideline and up to 1/4" for long belts. Still, shimming for minimum is best. Throwing or twisting belts is not fun.

I found some things that needs correcting. Hopefully that will help.

Misaligned belts become more of a problem as the RPM increase, and the distance between the belts increase. I would want the alignment pretty close (1/8" max misalignment) with that much space between the pulleys. You also want to be sure there is no flex or give in the mounting brackets. Gene

The power steering pump pulley is mis aligned quite a bit on one of my engines and I've never a problem with it.

Well it's as good as it will get. I was pulling my hair out and decided to get back to basics. Its decent now. And I decided to make the laser work.

Started with getting the alternator pulley vertically square to the crank pulley - made a new front alternator pivot bracket to fix it. That helped a lot! The alternator pulley is still out about 1.5 degrees horizontally, but that would be hard to fix (another bracket) so it will stay as is - don't think that it will be a problem. Then I aligned the idler pulley to the crank pulley. Its decent. Worst case looks like the most any of it is out is about 0.150 inches.

Attached are some pics of the laser. I made the aluminum adapter and targets. Worked out real well and it made it much better to figure out what was going on. You can see the alternator pulley vertical alignment before and after.

I totally agree on the RPM part...but

Think about that. Pick a LARGE amount of misalignment in order to visualize an example----say 1 inch.

Now put two pulleys really close together.... 1 inch off would be a disaster.
Now put the pulleys really far apart (like 3 feet)... 1 inch would work fine.

I don't disagree...........

How fast an engine rev's also comes into play.. My hemi could throw or break a belt in one hit. Changed to a top cog belt that actually slips a little on hit and hasn't popped off in 8 years. Chevy 302's did the same thing because of how fast they rpm. Probably the reason you couldn't get ac on the cars because you couldn't get the long belt to stay on.

I'm sure everyone has a little different experience, but I have a power steering pulley that's AT MOST 1/8" out of alignment and it keeps loosing the power steering adjustment bolt. I plan to add another washer to my spacer.