alternator belt issue

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Vitamin c

Vitamin c

Vitamin c
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anyone have any issues keeping your alternator belt from coming off ? 410 stroker, stock style Powermaster alternator, stock pulleys. Ive checked and rechecked the pully alignment with a straight edge, replaced the power master pully with a deeper stock style with no help. the belt is a new Year one repro that im replacing with a different brand or style and see if that helps, but i cant see any problems that would cause this. I even pulled the field wire to see if there was a charging issue causing the problem
 
Yes I'm having the same problem. I'm using the Power Master alternator (part number 7018, 50 amp round back), single-grove pulleys from BPE and a Year One belt.

When I ran the engine on the dyno (6,000 rpm) the belt stayed on the motor, but now it's in the car the belt is coming off. My car is a four-speed and it appears to come off when I'm hammering it and banging first-to-second gear. I'm using poly engine mounts (stiff!) and a torque strap. What's your set up?

I'm buying a Gates belt and rechecking pulley alignment today.
 
Check for end play in the crank and centrifugal runout of the crank pulley. Just a little off at the crank will make a lot of difference in a long span of a belt.
 
I had the same problem with every brand except Gates/NAPA. The taper on the belts that come off is to sharp allowing the belt to cawk in the pulley eventually it walks right off. The Gates/NAPA belts have less taper and fit the pulleys better. The top of the belt actually sits a little higher than the edge of the pulleys.

My expereince was once a new belt got thrown once it would come off every time I rev'd the engine past 5000 rpm. I have had the same Gates/NAPA belt on the car since I was told about this in 06 (~ 25k miles) and haven't had a thrown belt.

Interestingly I was at the local parts/auto body supply store and the old timer working there told me about the different tapers and suggested I go down the street to the NAPA store and get the belt there.
 
dgc333 said:
I had the same problem with every brand except Gates/NAPA. The taper on the belts that come off is to sharp allowing the belt to cawk in the pulley eventually it walks right off. The Gates/NAPA belts have less taper and fit the pulleys better. The top of the belt actually sits a little higher than the edge of the pulleys.

My expereince was once a new belt got thrown once it would come off every time I rev'd the engine past 5000 rpm. I have had the same Gates/NAPA belt on the car since I was told about this in 06 (~ 25k miles) and haven't had a thrown belt.

Interestingly I was at the local parts/auto body supply store and the old timer working there told me about the different tapers and suggested I go down the street to the NAPA store and get the belt there.
Click to expand...

Yup, I mentioned that in another thread about a slipping belt.
The cross sectional \_/ dimensions of a belt is called section and identified with letters, Like F section belt in our older cars? ( I forget )
I think appliance belts were D section but I'm one of those old timmers that has forgot a lot of what he learned over the years.
 
Demon 408 said:
Yes I'm having the same problem. I'm using the Power Master alternator (part number 7019, 50 amp round back), single-grove pulleys from BPE and a Year One belt.

When I ran the engine on the dyno (6,000 rpm) the belt stayed on the motor, but now it's in the car the belt is coming off. My car is a four-speed and it appears to come off when I'm hammering it and banging first-to-second gear. I'm using poly engine mounts (stiff!) and a torque strap. What's your set up?

I'm buying a Gates belt and rechecking pulley alignment today.
Click to expand...
im using the power master #7018 with the billet machined pulley. I had the pulley changed out to the origional mopar style with still no help. I picked up a Dayco top cog belt this morning and will stop by napa on my way home and see what they carry. i was told by the parts store that the year one belt looks like there lawn and garden belts. The stroker revs so fast im not sure whats going to happen.
 
dgc333 said:
I had the same problem with every brand except Gates/NAPA. ...My expereince was once a new belt got thrown once it would come off every time I rev'd the engine past 5000 rpm. I have had the same Gates/NAPA belt on the car since I was told about this in 06 (~ 25k miles) and haven't had a thrown belt.
Click to expand...

I just got back from NAPA. I bought the best Gates belt the stock, it's a NAPA 25-7475 (Gates 7475), only $7.23 with tax. I read the same thing about once you throw a belt it twist the belt and it will try and walk off the pulley. We'll see if this works.
 
Demon 408 said:
I read the same thing about once you throw a belt it twist the belt and it will try and walk off the pulley.
Click to expand...

I just finished going through the same thing. After a belt has been thrown once, you might as well pitch it or you can try to get the parts store to take it as a warranty return. If you're in a pinch, you can put it back on to get home. You could also keep a spare of each in the car, which is what I do.
 
it feels to me like the year one belt has some torn cords or something going on, so i would agree that once its been thrown and stretched its probably junk
 
You guys need a smaller crankshaft pulley...the stock crank pulley is accelerating so fast the belt just slips...Some engines will cook the belt from the friction of the pulley slipping past the belt.
Best fix...Marchs pulleys...
 
Rob R said:
You guys need a smaller crankshaft pulley...the stock crank pulley is accelerating so fast the belt just slips...Some engines will cook the belt from the friction of the pulley slipping past the belt.
Best fix...Marchs pulleys...
Click to expand...

I think I'll try the $7.23 fix first...but thanks for the input. I'll let Vitamin c make up his own mind because this is his thread.
 
Rob R said:
You guys need a smaller crankshaft pulley...the stock crank pulley is accelerating so fast the belt just slips...Some engines will cook the belt from the friction of the pulley slipping past the belt.
Best fix...Marchs pulleys...
Click to expand...
well id have to agree that the belt and alt pulley are slipping. after a couple tests last night the belt and pulley were pretty hot. the stroker revs so fast that i dont think the alternator can spin up as fast. What are you using for march pulleys?
 
keep in mind that a smaller crank pulley may cause a charging/cooling problems
 
Demon 408 said:
I just got back from NAPA. I bought the best Gates belt the stock, it's a NAPA 25-7475 (Gates 7475), only $7.23 with tax. I read the same thing about once you throw a belt it twist the belt and it will try and walk off the pulley. We'll see if this works.
Click to expand...

When I posted about the Gates/NAPA belts I couldn't remember the number but 7475 sure sounds like the one I am using.
 
There's no issues with cooling or charging when you use the smaller crank pulley...I've built LOTS of engines and everyone I build I've put a set of pullets on...These are all engines that are driven on the street and make on average 1.4 to 1.8 hp per ci...Even with the most mild combos I shoot for 1.2 hp per ci in...
I've never had a problem with the March stuff...

widebelt.jpg

vgroove.jpg
 
The Gates belt fixed my problem. I went out and hammered it in 1st and 2nd gear and the belt stayed on. Good luck with your new belt Vitamin c.

Engine (1).jpg
 
Demon 408 said:
The Gates belt fixed my problem. I went out and hammered it in 1st and 2nd gear and the belt stayed on. Good luck with your new belt Vitamin c.
Click to expand...
i have picked up both a Dayco and a Gates. im headed to the strip today after work for some test runs, ill let you know. Anyone run the Moroso alt. pulleys? they have a 5" single groove for 40.00. hell, ive got half that in belts
 
put on the dayco and tightened it a little more than i like, but it held up just fine through three test runs. I may order the moroso pulley just for extra measure.
 
OK, belts still in good shape, but on to an electrical overcharging issue. Im moving the problem over to the electrical and ignition forum
 
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