I have stock type pully setup of a 70's truck and have been using this REALLY old alt. belt. Well it finally turned over and ruined so i had to replace it. I had tried using different belts and they came off. So I am going to the track Saturday and any suggestions Ya'll have to keeping something on there would be appreciated. Yes everything lines up.

BTW Yes I am bringing 3 extra belts, probably pick up another one today just in case. It's a bbc 468 and runs 11.30's or so NA and turns around 6500-7000 tops.

I would get a deep groove pulley for the alternator

I went through that on just about every pass,....it would flip the belt over and then sometimes toss it.

Changed to "dayco top cog" belts for alt and power steering and have not had a problem since.
I use a 15430 for the alt/water pump/crank
and a 15395 for the PS/crank

How about considering a serpentine set up? That's what I would do.:thumbsup:

http://www.alangrovecomponents.com/Catalog.htm

Bob

I'll second the Top Cog belt.

I had the belt rip a hole in my top radioator hose once. Get a deep groove pulley and the top cog belts. If you don't do either before Sat. Take a top radiator hose with you as well.

Troy.

if you go to pep boys they sell a dayco belt depending on the length you need but you want to get the 11/32 belt in othere words a 46 inch belt would be a 11460 on the pn 15460 would be a 15/32 belt.i used these belts for many years and had no probs throwing them.

Do you have the same size belt on another vehicle. If so swap the new one on it and then run the old one.

I have the same problem. I can run a old belt, but will throw a new one every pass.

Get the alt. as close as possible to the center of the engine, as close as the bracket will allow. Then get the appropriate length belt in a Top Cog. I use to twist/turn/toss belts at the track all the time. After I moved the alt. as close as possible to the engine, it stopped.

Put a idler pully off of a serpentine set up from a mid 90's chev truck works great.
About $15 at the parts store.
used it on small blocks and big blocks, put it on the drivers side where the slack side is. Never come off again!!

If the pulleys are aligned perfectly and the brackets do not flex you will not loose belts. The Dayco top cogs will tolerate a little more then most belts but IMO the real issue is usually pulley alignment or bracket flex.

The perfect time for fixing this is when the engine is out of the car -- I like putting everything on the motor while it is on the stand and getting right in there with a straight edge. Its nice to do trhis with the engine out because you have easy access -- you can look at whatever angle you want and really be anal :D

In some cases I have welded sloppy bracket holes partially closed and redrilled them, other times I have welded in extra bracing behind PS pump brackets, etc. BBC passenger side mount alternator brackets tend to get a little sloppy over the years (especially the lower IMO)

Just my opinion.

Cool, some things I didnt think of in here. I will return these belts I have and get the shortest that will fit in the dayco top cog. Those belts have no grooves on the inside of them. I have one of them now, and two NAPA ones. . I installed a moroso 5" pulley today with a new 49 5/8" belt, so I guess I'll change it again. What about a fan ? The stock pulley had a fan as one piece. Can I get some kind of fan to go behind the Moroso pulley ? Do I need one ?

I'm using a 5" pulley with a fan from an older alternator, also running a smaller diameter crank pulley, but alignment is the key, as Eric stated. :thumbsup:

I'm using a 5" pulley with a fan from an older alternator, also running a smaller diameter crank pulley, but alignment is the key, as Eric stated. :thumbsup:


Hmm, see if I can't run by the salvage yard in the AM if they are open.

I had this problem on my bb 66. I thought the pulleys were aligned perfect but on close inspection I could see the factory lower alternator bracket flexing while reving the engine. I bought a billet March alternator bracket and problem solved, a little pricey but no more thrown belts.

Mike

I installed a moroso 5" pulley today with a new 49 5/8" belt, so I guess I'll change it again. What about a fan ? The stock pulley had a fan as one piece. Can I get some kind of fan to go behind the Moroso pulley ? Do I need one ?
That 5 in alternator pulley is a race only deal. If you drive on the street, you will find that your alternator won't charge the battery at lower rpms, and you could end up with a dead battery. Yes, it needs a fan or the alternator will overheat.

definetly dont go to large on the Alternator pulley or too small on the crank pulley or it wont charge.

The problem is that on most Power Steering/Alternator/WP setups the alternator is mounted pretty far away, so the belt required is humongous and any incorrect alignment/flex will throw the belt. Very unforgiving.

I spent alot of effort developing bracketry to keep the alternator lined up under load.

Fix the problem. i threw a belt on my alternator at Island Dragway once, and it went towards the motor, wrapped around the balancer and managed to pull the rubber out of the front seal.
Also gave my fuel line a beating (thank god for stainless braided lines!).

A thrown belt has the potential for a very poor ending! That was the sole reason in my mind when i bought an On-board fire suppression system. Something as simple as a belt had the potential of starting a serious fire.

BTW it took me 6 hours to clean up the oil under the car from that mess, since i didnt realise it until i was driving home that there was oil everywheres.


Needless to say after that event i had no problem spending as much time/resources as required to fix the problem, and keep my accessories.

Since then i've taken it one step further and removed the accessories, and swapped to a passenger side alternator mount that requires a short belt.

That 5 in alternator pulley is a race only deal. If you drive on the street, you will find that your alternator won't charge the battery at lower rpms, and you could end up with a dead battery. Yes, it needs a fan or the alternator will overheat.

I found this to be true with the OEM style alternator and external regulator,had to rev it to get it to charge. I've since changed to an internal regulator and it charges fine. I put the charger on it this week after changing plugs and checking the timing, the 10 amp charger was on the car for maybe 10 minutes and it went to fully charged. This is just starting, racing and parking at the track, hardly enough time to charge much at all.

Somebody can laugh at me but after years of never throwing 1 belt, I had put new belts on and it started to throw them. They had cogs in them. I changed to lawnmower belts and the problem went away. That is what I'm running on my BB

Somebody can laugh at me but after years of never throwing 1 belt on my SBC's, I had put new belts on and it started to throw them. They had cogs in them. I changed to lawnmower belts and the problem went away. That is what I'm running on my BB and they have been working good. They won't stretch at all.

I had the same problems on a stock big block. I went to a narrower belt so it dropped lower into the stock pulleys. No more belts flying off or flipping over. Dave

Ok well good thing i brought spare belts. I could'nt get a fan that fit yesterday so I ran without. The belt only came off once, but turned over on three runs, only the first it stayed on correctly. Reinstalling the turned over belt came off the next pass, so that messed up my testing a bit, cause that run was 2 tenths and 2 mph faster. I will definitly be switching to a pass side low mount kit and manual steering box. I brought generator and batt charger so any low charging caused by the larger alt pully was taken care of. I wasnt able to get the 11/32 belts so had to make do with the 15/32 width. All in all good night, just really hot. I'll make a post about the day later.

Thanks for the replies.

Back on the Aug 4-6 weekend I threw the belt 11 times out of 12 runs. If I count the belt coming off while timing the engine it would be 12 times. Scared the heck out of me when the belt came off at about 4000 rpms while holding the light down there.

The pulleys were lined up almost perfect as measured using a straight edge and a string line. Tried shimming alternator and water pump pulleys out of line. Tried narrower belt. Tried tight and loose belt tension. Even changed the chrome water pump pulley for GM OEM pulley. Tried another alternator. Tried with the disconnected alternator wiring. The only thing I can think of as a remaining problem is the chrome crank pulley. I have another 454 in another car with the standard setup and it has gone to 6500 with absolutely no belt problems using all factory pulleys.

Nothing worked to keep the belt on that weekend at the track.

So now I am going with the Moroso water pump drive kit. For sure this problem will be solved. As well as the other benefits of using electric pump drives.

Back on the Aug 4-6 weekend I threw the belt 11 times out of 12 runs. If I count the belt coming off while timing the engine it would be 12 times. Scared the heck out of me when the belt came off at about 4000 rpms while holding the light down there.

The pulleys were lined up almost perfect as measured using a straight edge and a string line. Tried shimming alternator and water pump pulleys out of line. Tried narrower belt. Tried tight and loose belt tension. Even changed the chrome water pump pulley for GM OEM pulley. Tried another alternator. Tried with the disconnected alternator wiring. The only thing I can think of as a remaining problem is the chrome crank pulley. I have another 454 in another car with the standard setup and it has gone to 6500 with absolutely no belt problems using all factory pulleys.

Nothing worked to keep the belt on that weekend at the track.

So now I am going with the Moroso water pump drive kit. For sure this problem will be solved. As well as the other benefits of using electric pump drives.

Yeah, horsepower LOL no belt dropped me to 11.25 @ 120. I am also considering a w/p drive and electric fan.