TJefferson2020

I have a nice mount made by Toddalin here but my alternator sits a little cockeyed. I was getting a belt squeal so I tightened it up but now it's tossing the belt. What is the best way to see the alignment of the pullies? Yard stick? Something else?

Any way to measure?

Nowhere Man

I would think by eye balling it you should see how fair your off.

Bluestripe67

Be smart, use a yard stick or some other true device. Don't trust your eyes. Dennis

68hemi

Do you have deep groove pulleys?

TJefferson2020

I think that's how I ended up with the problem. I can see it is cockeyed but don't see how that mount could be **** eyed. It's pretty solid.

I'll get some pics tomorrow.

I'm not sure. I'll take some pics and maybe you can tell me. I believe the ones on the motor are stock for the 1970 LT1. Alternator is aftermarket.

68hemi

If they are then they should be deep groove. Chevrolet put them on all of their cars built with the high lift solid lifter cam engines since 1957 to keep them from throwing the belt at high rpms. If the alternator is after market it may not be. I believe deep groove pulleys are available aftermarket/reproduction.

buns

https://www.corvetteforum.com/forums...ment-tool.html

63 340HP

Excellent link with suggestions and photos (worth a thousand words).

I use a piece of 5/16 all-thread rod with jam-nuts capturing two washers spaced apart (adjustable spacing for different pulley diameters), to ride in the pulley groove.

Check above and below the pulleys to be aligned. The top may look aligned, and a bent mount or missing washer under bracket bolts can throw the bottom off alignment.

MAD IN NC

i got lucky on 65... but the 69M1 resto had me fighting it for weeks.... with serp belts

tbarb

I had that problem on my 67 but it was not throwing belts, the alternator just looked crooked compared to the straight crank/water pump pulleys.

In the end what I found was the lower alternator mounting boss (on the alternator) where the long 3/8 bolt goes through was not flat where it bolted to the engine bracket so when bolted tight the housing was not straight. I had to file it flat and in doing so needed to use a thin flat washer to make up for the material I took off but it tightened up straight.

TJefferson2020

I spent this morning re-aligning the alternator. It needed to come forward a bit and I used a washer to tip it slightly to align.

Then I ran some slow motion video to see what it was doing at higher RPM's.

It's grainy and a little blurry from enlarging it.

• Start up and idle
• Camera at 10% of normal speed 3K-3.5K RPM
• Alternator close up - 10% camera Speed - 3K-5K RPM
• Alternator close up 3% camera speed - 3K-3.7K RPM
• Idle shut down

Note how wobbly it is at 3% speed. Bolt's are torqued to spec - Although I'm going to check the "front to back" bolt.

Belt does not squeal or jump so far.

That wobble might be typical for this set up for all I know.

Robert61

The water pump pulley has WAY too much run out. Investigate what's causing that, bent water pump shaft, pulley not seating correctly on water pump register. Then your alternator is not square to the engine by quite a few degrees. And yes it matters or yo wouldn't be tossing belts.

TJefferson2020

Yes I can see the fan wobbling. I'll look closer at that pully. It's been on there for over a decade with no issues.

EDIT: after looking at the video again - holy **** that main pully is out of whack. That seems to be causing the alternator to move.

I know the alternator is not square. That's what I'm working on. It's way more square then when I started this morning.

I'm trying to get it both square to the block and aligned with pullies. The alt also may be forward a bit too much now after I adjusted it.

I'll post some before pics.

I changed out the header mount with a nice one from cf member Toddalin. Previously it used the crappy hooker type - but never threw a belt for 11 years.

I assume I just need to keep adjusting. One oddd thing is that it's **** eyed but if you look at the mount, it can't be. Yet, putting a washer in tips it straight.

I was surprised to see the belt is not deflecting much and looks pretty stable. But the assembly sure is moving.

However, it may be possible that the slow motion is showing something that most old cars do. But you can't see it unless you slow it down.

Nap time now. I'll hit it again in an hour or so. I may take the entire assembly off and start over. There is one bolt that is brutal to reach because it's in the bracket. I can't quite get a wrench on it.

MikeM

It looks to me like the water pump shaftis doing the hootchey coo and that may be moving the alternator. Even at that, the alternator should not be jumping around like that. It should be dead solid.

Check your water jpump and see if the bearing is loose and review your alternotor mounting..

Robert61

The water pump pulley run out is not normal. It's bad enough that it's moving the alternator. And those header mounts can be off. Just keep adjusting til it's straight. One other thing see how high up in the groove the alternator belt is riding. The other belt is down like it should be. The alternator belt is a little too wide. Once you get the water pump pulley sorted and the alternator aligned the alternator needs to be way more stable than it is now.

68hemi

You have too many possibilities going on there.

If it were me I would start from square one by taking the belt off and running the engine to see if the crank pulley is running true. Then I would remove the water pump pulley and inspect to make sure it is not tweaked and is sitting true on the water pump. Then get a small enough belt to go just from the crank to w.p. (may have to put the belt on the pulley first and then bolt it to the pump) and run the engine to see if it is true that way you will be able to tell if the pump shaft is tweaked. After all of that is eliminated you can start shimming your alternator/bracket IF necessary.

TJefferson2020

I removed all the belts and water pump pulley.

1. The alternator belt is too wide - good catch on that.

I checked the water pump hub and it seems fine. Not bent. Has the tiniest amount of play but it seems fine.

The craptastic after market pulley looks (to my eyes) like the center hole is off center! It could be an optical illusion but I know it's a cheap, Chinese part.

I ordered an original GM pulley from Ebay - OE #: 3995642 - two grooves, 1970 LT1.

In researching this I found a thread of mine here in 2005 asking about water pumps!

Also took some photos.

Note the engineering of the mount. It sits flat on the headers - it should be absolutely square. Yet when the alternator is attached, it isn't. You can see where I put the washer.

Robert61

Its hard to tell sitting here on my couch but it looks like the fan shaft is running out the same as the pulley. Spin the water pump pulley with some type of pointer close to the hub that wont move. See if there's run out in the face of the water pump flange.
Is the hole in the fan clutch 5/8 or 3/4"?

TJefferson2020

I did that with a sharpie. Very little variation in terms of run out on the hub. Probably not the most accurate method.

I'm going to also replace the crank pulley with the correct pulley (mine might be correct - won't know for sure until I remove it). Over the years, who know what might have been bolted on to this motor.

I rebuilt it (a couple times) since I've had it but used the pulleys that were on it.

I did put on a new water pump in 2005 apparently.

I'm going to call Alan Grove Components to see what my options are for mounting the alternator - low profile, pass side.

Their web site is pretty screwed up. I hope they are still in business.

Alternator mount been an issue since the first build - even though it worked well all these years - it was funky. That chrome hotrod arm style bracket on top is flexible - I also cut it shorter so it didn't hit the hood.

That ain't right either.

TJefferson2020

3/4" hole

It really acts like the hole in the pulley is off center.

Edit: just pulled the crank pulley to see what part number and to check it. It's not the right one for the motor.

It has a part number of GM 3744034 - for 63-68 327

The correct part number is GM 3858533 for SHP motors without AC (two deep grooves).

Looks like I'll order one of those too...