I have an 81 and did a vortec head swap and used tall valve covers to clear the roller valve train.

When I first got the car running I noticed that the alternator was adjusted almost all the way out and there was still slack in the belt, enough to spin the WP by hand. I spent the better part of the weekend then searching for a belt that will fit with little luck. I found the best one they could order and i can still spin the wp by hand.

my issue is because of the tall valve covers it eliminates a lot of the adjustment in (towards motor) and due to having the alternator farther out, I'm maxing out my adjustment and cannot get the belt tight enough.

does anyone have any ideas or know of any products that will allow for more tension (moving alternator out)?

I really only need probably another 1/2” of available adjustment to make it work. More would be better but not hoping!

thanks all

 

What belt do you currently have on the car now? Have you tried a wide belt, that would ride a little higher on the pulley?

 

A “normal” v-belt. Dayco 15555.

 

I too have a 1981 with a recent Vortec swap, but with stock valve covers. My alternator is at the end of its adjustment, but the belt is tight enough. I think it would be simple to cut the bracket and weld in a piece to lengthen it. Did you find a shorter belt, and can you tell me the number, so I can try it on mine?

 

I use the Gates chart and it works by replacing the 15 in Dayco number with a 7. Here is a list of other sizes they offer around what you have. You want the shortest belt you can put on the alternator. To work around the valve cover issue, you might want to take the water pump pulley off to get the belt into the pulley groove and then put it on. This might get you a smaller belt with more adjustment.

Belt Length Length Top Width Top Width No. (in) (mm) (in) (mm) Angle
7516.................t.52 1/8 1323 13/32 10 36°
7520.................t.52 5/8 1336 13/32 10 36°
7525.................t.53 1/8 1348 13/32 10 36°
7530.................t.53 5/8 1361 13/32 10 36°
7535.................t.54 1/8 1374 13/32 10 36°
7541.................t.54 5/8 1386 13/32 10 36°
7545.................t.55 1/8 1399 13/32 10 36°
7550.................t.55 5/8 1412 13/32 10 36°
7555.................t.56 1/8 1425 13/32 10 36°

 

the one im running right now is a dayco 15555. If i find one that works ill pass it along.

 

thanks sig. ill have to work on getting things back together a bit and take a photo of what it looks like. I have maybe a 1/2” in/out for adjustment.

 

So looking though jegs, summit, google in general - this popped up.

in the comments someone specifically mentioned sbc, vortec heads and tall valve covers and it working.

what are your thoughts? Kinda seems too good to be true?

so far, its the best lead yet

 

That looks like a good option, but the only question would be is how much threaded movement does the bar have to adjust.

 

I was thinking the same thing! nNow how easy would it be to source a new turnbuckle if the one supplied with the kit is too short?

 

My local Home Depot has them, but not that nice looking. Makes me wonder if maybe you can modify what you have now with one from Home Depot.

 

Its quite possible, would have to look at my setup on how its mounted and see where the easiest point to mount the adjuster.

the way my luck is with the car - it wont be easy 😂

Edit: here are photos of how little room i have to play with

Just about to valve cover

Adjuster farthest in

Adjuster farthest out

Farthest out

 

Whelen1,
As wonderful looking as that billet unit is, I will tell you that when you start changing the design of the original GM ALT, bracket, etc it tends to alter the fan belt alignment.
Ever so slightly. Next thing you know, the belts are not tracking correctly.

Also note that some individuals mount the bracket behind the ALT housing "ear" instead of the front. The arch of the bracket can and will lay right over the arch of the ALT housing. Then the bolt is threaded in from the back, not the front. You may or may not have that option depending on where you have the other end of the bracket mounted at.

 

when looking at the belt track as it is now, its slightly to the motor side which is causing it to be too close for comfort to the PS pump. So thats something i need to address when i can get things back together. Speaking of belt tracking.

im not a fan of the billet l, i like black, BUT it seems as though its really my only choice to fix the tension issue which is causing an overheating issue.

if I could find out what the alt adapter bracket is actually called id keep everything except the oem tension unit and get an adjustment rod separately. But ive been looking for over an hour and cant seen to find the right search terms.

 

What about swapping the alternator pulley to one slightly larger in diameter.
You would need to calculate how much it would change the rpm of the pulley and make sure it would still be spinning fast enough at idle to keep the battery charged and put out enough amperage to run all your accessories.
Many people have swapped pulleys to achieve different pulley rpm and there are numerous different sizes to choose from.
Just thinking outside the norm and presenting different options.

 

thats a great idea and never thought of that! Only issue I see is not having a whole lot of adjustability right now, only have about a 1/2” of working room.

but if i can figure that out, i may go smaller to give a little more umpf at idle.

 

My '80 alternator bracket has always been hard to deal with. Hard to get the alternator backed off far enough to change the belt and then running out of adjustment when tightening.

I just remove one of the head mounting bolts and loosten the other bolt to allow the whole bottom bracket to swivel down, then change belt, then reinstall the bottom bracket bolt.

 

It seems over the years with forum members that they buy 3-4 belts at the local NAPA and return three of them.
One is too short, one is too long, one is too narrow. One is goldilocks just right.
Some stores are cool with that. Others find it a pita with more return paperwork.

I too have the tall valve covers and it was frustrating to find that perfect belt that allows VC removal, and is not at the end of the bracket adj.

 

This might sound like a dumb thing to try but I found it helped when I was using the old style V belts.

If your belt has not been tight or just barely slipping it tends to get a nice smooth shiny surface where the belts make contact inside the pulley. I tried Emory cloth to get rid of the smooth finish (on the pulleys) and this works but takes a while and wears out your hands. I then tried using a sand blaster and that removed the smooth surface finish very quickly which allows the belt to get better traction. I then did it to all the pulleys and the squealing was gone afterwards. I have a 427 with Power steering, alternator and water pump and I was always fighting to keep the alternator belt from squealing.

Any belts that have a shiny smooth surface inside on the contact surfaces are going to make noise unless they are really tight. I finally got tired of playing and bought a March Serpentine Conversion kit for my 427. The March Serpentine conversion kit uses a Turn-Buckle mounted on the Alternator bracket to get the belt tight and it works very well. I would prefer to have a tension pulley but the March Turn-buckle works and is very easy to adjust. Serpentine belts are a great improvement over the conventional V-Belts, In my humble opinion of course. This way I just keep one spare belt in the car instead of a set of them.

 

As mentioned before, I have cut the top bracket and added a piece in to move the slot. Works great and looks stock if done right.