Just lost my second altenator belt(V belt) after a trip to 6000rpms.I've checked alingments and that all looks good. Would a larger pulley on the alternator help?

use TOP COG belts!

if they dont solve it then a deep groove alternator pulley would help.

Alignment is only part of the picture. Another huge part of it is stability.

If you rev your engine and your alternator vibrates, it's unstable. Make sure your brackets are up to the task.

I used to throw belts all the time until I found a slightly better way to mount the alternator with my headers (short water pump).

I'm not as familiar with BB bracket configurations, so I don't know if stability is an issue for you or not.

Is it possible that you have an "out of round" pulley somewhere? Might want to check 'em with a dial indicator.

Alignment is the first issue to look at. Get a straight edge down along the pulleys and check it. If it's good there try the goodyear gator belts. If that doesn't work, like my 2 previous cars sporting big blocks. Install a serpentine kit and forget it.
I went through all of this and have come to the conclusion that a car with a decent size stall convertor can free rev almost as quick as if it was in park and literally sling the belts no matter how sweet the alignment. Some setups just mandate a serpentine kit.
I know, been there quit a few times.

Good luck
RandyB.

Current rides.
31 chevy prostreet 3 window/ 454
67 RS/SS

Previous rides.
67 chevelle prostreet/468 roller motor
70 cheveele SS 396 roller motor
87 Grand National
72 Cutlass
72 Nova SS
86 Monte SS
68 Camaro
82 S10/ 400sb

I've been using the "Gatorback Belts". They seem to stay a little longer but eventually give up too.Guess I'll quadruple check the aligment and see if I can find a deep groove alt. pulley thats larger in diameter."March" has a nice serpentine set up but dang its expensive!

You can also try the Moroso deep groove alternator pulley.This will help from throwing the belt.

I saw in a post once where someone recommended using a "laser dot" pen to check pulley alignment - lay it in the groove, and see where the dot lands in the other pulley - seems like a great and accurate way to check your alignment.

Is there stock GM serpentine set up(like a particular year and model)that would bolt up to my big block and run the water pump,alternator and power steering?

My alternator still has the stock, deep groove one I put on it WAY back when b/c of throwing belts!!

And check your Alternators front bearing b/c if it is the least little bit bad, it will cause this... That's how I found out my bearing was going bad after I put the deep groove pulley on it..

pdq67

The alternator is new and I checked it again this morning.Rotation is good and the pulley runs straight.Man I gotta get this fixed,all this beautiful big block power and I can't even use it. smile.gif

put the deep groove pulley on it!

check allignent and a shorter belt,use a riding lawnmower belt(kinda has a type of cloth around them,sold at auto zone)lost my belts at 6000 every time did these two things spin to 6700 now and havent lost a belt yet.
shane

you know i had an old piece of crap belt on my nova and never threw a belt going all the way to 7,500-8,000 RPM tons of times. Then i got a new one cause that belt was slipping and such, got the Gatorback belt and first time i got on it only going to 7,000 i threw it right off!!! Weird.

MY BB would toss the belt at high rpms I checked to see if my pulleys were lined up , witch they were,so i went to a DAYCO TOP COG BELT and it did the trick graemlins/hurray.gif I think it cost around $7.00 at the local FARM AND FLEAT good luck graemlins/thumbsup.gif

the belts loosen up after you wear them in a little, so it might be a simple solution like retighting them.

I use a cheap belt and I modified the brackets for stability. I've hit 7000 a few times and 6500 several times with no problems.

here is something else you guys should be aware of............i too for the longest time had problems with my bbc throwing belts specially after i was making enough horsepower to run 12's ...........

heres the deal.......i tried all the tricks cogged belts, deep groove over size pulley, made sure with a long straight edge that all pulleys was perfectly aligned, even went as far as dishing out money for new pulleys and brackets...........

then i noticed my lower radiator hose was being sucked shut when my belt was being thrown.( of course this was in the driveway)

so i bought an industrial type lower hose that was super thick and had the wire molded in it................because the stock lower hose the wire was being sucked up into the water pump................then i started to pop out the water pump gaskets.........

so here i sit with new everything and im still throwing belts on my high 11 sec ride..............and popping out water pump gaskets...........

one day i got so P.O. i tighten the belt so tight that i coulded get it no tighter and there was no slack to speak of...........

so i pulled up to the start line and launched before i got to the 60 ft mark i had blown my stock water pump off the block! all that was left on the block was the 4 bolts.

i fixed the 300 bucks of damage to parts and once again i just tightened then belt to just a normal setting and i blew the water pump off the block again at the race track.......


looking back the problem ......temp of the motor did not have the thermostate open.........the car was hydro locking the water pump(stacking up water with it no where to go)........belts was flying off because the pump was locking up with water......i took off the industrial type hose.........

i replaced everything once again and i took the thermostate out and i let the car warm up slightly and ran it.........not a problem...........i put the thermostate in and let the car warm up not a problem.................


when i went back and looked at the time slips with belts that was thrown they was all cold passes.........the passes that didnt have the belt throwing off was warmed up passes......................

water pump being blown of block(and popping out gaskets) was when i bought a hose that would not suck shut........all the years the bottom hose was being sucked shut was more or less a safty device that just allowed the belt to throw off.......of course the motor was to cold where the thermosate was not open yet........

as of now i dont have problems with belt throwing now more since i had to find out the hard way.............now that i understand what was going on now i can avoid the problem........

i have drilled a few big holes in my thermostate and i run a weaker hose on the botoom just incase and to allow it to be sucked shut..........

I use to have the same problems; take the engine to any kind if rpm's and it would toss the belt. :mad: Alignment looked good, could not find any thing wrong. Finally took the belt to the local auto parts store and the guys there found a belt that had the same length but was "alot" narrower. Sat down in the pulley grove much further. No problems since. graemlins/hurray.gif

Nothing I did solved the problem.
I made a small guide that bolts on the lower brace. I does not touch the belt, but rides about 1/8 inch away. Problem solved.
I ruined nearly 20 belts before I did this.
I have seen idler pulleys mounted there also.
I put the guide on because it is nearly invisible.
I would like to try an idler pulley.

Also disable the ignition and have someone crank it over. I had wobble in the crank pully so I got another one, it was "bent" to so I got another one. Turns out they were fine and I goofed by not evenly running the 3 small bolts. You really need to tighten them at the same time (small increments), like a quarter turn, then the next and so on.