Belt size for 5%JS and 5%SC pulleys?

rzimmerl

Registered User
My stock belt is too small for this setup, it is bottoming out the tensioner on the AC compressor and slipping alot. I just was seeing what anyone else was running before I order a couple belts to get the correct size.
 
I have been running stock belts with the same set up as yours for over a year with no problems.....
 
I'm also running same set up with stock belt ,but it is very tight and hard to put belt on it.No problems so far.
 
I am also running a 3" tensioner pulley, if that makes a difference. I am swapping my inlet plenum and the only way I could get the belt off was to unbolt the tensioner.
 
Last edited:
rzimmerl said:
I am also running a 3" tensioner pulley, if that makes a difference. I am swapping my inlet plenum and the only way I could get the belt off was to unbolt the tensioner.
Just get one size bigger belt, it should work.You're having a problem with your stock belt because you run bigger tan pulley.Like I said before it is very tight with the stock size tan pulley
 
rzimmerl said:
My stock belt is too small for this setup, it is bottoming out the tensioner on the AC compressor and slipping alot. I just was seeing what anyone else was running before I order a couple belts to get the correct size.
This makes no sense to me. Is the belt too short and therefore pushing the tensioner pulley against the AC bracket? If the belt is short and therefore tight, why would that cause it to slip?

If the belt is too long then the tensioner will be loose and the belt will slip.

If the belt is short and you are still slipping then you are attempting to run too much boost.

Anyway, it depends on what JS pulley you have. If it's an SCI pulley then you should use a stock belt. That's what I used. Stock is 39.3" long. If you want a longer belt you can get it 40.0" long. If you are having a hard time installing a 39.3 belt then the 40.0 will help but it may aggravate your slippage problem rather than help it.

I don't think there is any size in between those two.
 
Yes its an SCI JS pulley. I am running about 17-18lbs of boost and it probably is too much boost for an entirely stock long block.

To get the stock belt on i have to spin the blower and JS and push 1 rib on at a time. I didnt think it was slipping but there is black dust all over underneath the blower. The belt is 2 years old so I was going to repalce it, and was just getting a feel if anyone else had problems or what they were running.

I will put the blower back on tonite, install the belt and take pic of the tensioner position and see what you think.
 
Last edited:
I think the 415 is way too long. As said above, make sure what one you have now. It could be a 390 which would explain it being so tight. Anyway, I think a 400 belt will be just fine.
 
Back
Top