Pulley alignment question

I switched a while back from a generator to an alternator. Ever since then my belt has been squealing which tells me my pulleys must be out of alignment. I've tried eye-balling the alignment but that's not working. What's the best and/or proper way to align these puppies?

There are three pulleys, the crank pulley, fan pulley and the alternator. I can safely assume that the problem is with the alternator, I think. Oh yeah, this is on a short pump SBC. I'm running headers and using an aftermarket alternator mount and bracket. unlike an OEM bracket, it has all kinds of adjustment in every direction.

I've run out of ideas, any insights?

 

could be that it's just loose. The header type alternator brackets for the SBC generally suck. If you have a newer engine that has bolt holes in the ends of the heads, see if you can find a 1970s Vette type alternator bracket for it.

 

You say out of alignment? when you look at the pulleys from the side do they line up or is the alternator pulley ahead of or behind the crank and waterpump pulley?

Is the belt adjusted correctly? Is there any flex in the brackets holding the Alternator?
Some of those brackets were pretty light weight from what I remember back when I used them.

See what Squirrel wrote! Factory style brackets are usually the strongest.

 

Are all your pulleys matched to use the same size belt???

Use a yard stick and let the edge rest on BOTH sides the bottom pulley. Move it to also overlap the Alt pulley and decide which way the Alt needs to move to correct the misalignment.
Check the waterpump pulley while your at it.

I've seen some way out of alignment alternators etc that didn't squeel but would throw belts or tear them up quickly.
Are you sure your alternator belt adjustment is tight enough?
Do you have enough of the belt actually AROUND the pulley???
If you don't I could see it slipping and squeeling.

You might simply need a new belt and your pulleys cleaned up!

 

The problem is the belt is not tight enough. The belt on a generator does have to any more tension than reqired to make it turn. It charges all the time and the regulator just allows the voltage to flow into the system as needed. The alternator on the other hand has to have a tight belt. The reason being it only charges when the rectifier bridge and diodes are intergized electrically. The regulator is actually an electrical switch that supplies the current to the diodes and it begins to charge. The belt is actually free wheeling and all of the sudden there is a load on the alternator so the belt squeals. Also many alternators are diagnosed as being faulty or low output yet the real problem is belt tension. Hope this helps.

 

The pulleys could also be different. There are "deep" pulleys and "standard". Mismatched pulleys will cause a squeal to develop, because the belt is not seated correctly...

 

Try a new Gates belt and set it up tight. Go back after several miles and retighten it. should be good from then on. Also if possible go to the vette bracket. my opinion only

 

Since you only changed the gen. the crank and water pump should be in line. Look at what everyone else has said and look at one more thing, like your belt, not being able to get any tighter because of it's length ie. your out of adjustment. Auto parts stores sale belts that are an inch shorter in increments, which might be what you need? Take your old belt with you. Good luck!

 

my experience with gates belts is they are like a rubberband they just keep stretching and never seem tight. try a goodyear belt once and you'll never use a gates again.
i agree it's the belt, make shure it's the right width for the pullies and the right length, not to short.
that's my 2 cents

 

Wow! I love this site! I just posted the question a few minutes ago and already I have 8 responses. Thanks.

Do the 70's Vettes still use the short pump?

 

Usually if you have pulleys that are not aligned, you'll experience throwing the belt off, not squealing.

 

yes, that's why I suggested that bracket.

 

In the process of trying to solve the problem I cleaned up the pulleys and ran some 600 grit over the surfaces. Didn't seem to make any difference. The belt doesn't seem to be glazed. I will try your suggestions regarding alignment. The problem I have is that my engine sets so deep in the engine compartment that I really can't step back and get a good view of the alignment with my eyes.

I already cleaned up the pulleys and the belt is definitely tight enough and there seems to be plenty of wrap arount the alternator pulley. Because of the bracket I'm using I'm guessing it is an alignment issue. I'll keep at it.

It's pretty tight. I don't think it's a loose belt issue. I get what you're saying about Gen vs. Alt though.

It's hard to get a good look at the pulleys from the side. That's probably part of the problem I'm having.

I'm thinking that a factory bracket would be better too. I'm not sure what that Vette bracket looks like but I'd like to investigate that further. Does it mount to the front of the head only? I'm running headers and an aftermarket intake with no provision for mounting points so it would have to mount independent of the intake or manifold. Does that 70's Vette still use a short pump?

They seem to be the same as far as width and depth.

I may have to go with a smaller belt. I am almost to the limit of my adjustment but the belt is currently pretty tight. If it stretches though I may run out of adjustment room.

 

That's good to know. Would some place like Eckler's carry that bracket?

 

Maybe, give them a try. It bolts to the front of the head, won't work on 1950s-60s heads.

 

Thanks. I took a look at Ecklers. Yikes! Big bucks for those brackets. Maybe ebay.

 

Sometimes when a belt starts squeeling, nothing you do can stop it. What Im saying is.... The belt gets a "skin" on it. No matter how tight you get it, its a squeeler once it gets hot and forms a skin.

 

SAXMAN...run a piece of string around all of the pullys, then you can eyeball them. and the generater belt may not fit the alternater. i would buy a new belt and adjust it. how? tighten untell you can move the top of belt up and down, the thickness of your thumb...POP.

 

These people are good if they offer the bracket. Davies Corvette in FL.
www.corvetteparts.com

 

A lot of good suggestions here. I think one really valid point is that once belts start to slip, it's really hard to stop. A new belt might be the solution. If nothing else works, I use an Alan Grove under the head mount and have not had a problem with it. I'm only running three pullies like you.

 

You might try to string the alignment, Take your belt off and tape a string to the lower pulley on the inside edge and bring the string up to the other pulleys. Or get yourself a Belt Hog, It has a beam that shows alignment.--TV

 

Thanks Holeshot. The string is a good idea! I'll give that a shot.

I put on a new belt when I installed the Alt. It needed to be a little longer than the Gen belt because of how it mounts. It seems to be adjusted as far as tension goes but may not be lined up right.

 

I get it. Maybe a new belt is in order. I'm not sure what an Alan Grove is but I'll do a search. Thanks.

 

The string thing is a great idea. I'll try that. Thanks.

 

If you are worried about alignment, try putting a straight edge over the edges at the end of the pulley and see if it aligns with the other pulley. If it is out of alignment, it should be apparent.