FAQ: Upgrading Serpentine Belts & Pulleys?

Sir Psycho Sexy wrote:

Alright, im thinking i need to pick up a bigger idler pulley... The pulley i have is a 3.2, and i think i ought to be able to run it, but i need a bigger idler, is http://www.oreillyauto.com/site/c/detail/GATE/38019.oap?pt=02733&ppt=C0328 what i need?

Just to clarify, i am putting the motor in the car right now and this issue arose.

I dont know if this is the proper place for this or not... I hope so!

Why not just buy a smaller belt? Buy a Gates K060710 from O'Reilly. That's what I'm running with my 3.25". It's like $35 with a 3 year warranty.

I also recommend a smaller belt. The bigger idler will help a little but won't be quite enough for a 3.2.

You can run a 3.2" with the OEM belt if you increase the diameters of both the idler AND tensioner pulleys. Can even run 3.1" on stock belt. Why do this? Pulleys are much easier to change than belts. If you install a smaller belt, and ever want to go back to 3.4" (like I did), you'll need to change the belt back again, which kinda sucks. Changing the idler/tensioner pulleys is easy, gives you more options, and costs about the same as a belt. Also, you can always replace belt with stock instead of needing to remember a special size.

I already have a 3.5 tensioner pulley. My problem is that with the 3.2 SC pulley, with the 3.5 tensioner, and stock 3.0 idler, the belt is touching itself, not to mention being ridiculously loose.

Reason i didnt just go for a smaller belt was because the pulleys were pretty shot anyway.

I picked up the new pulley today but i havent gotten the chance to put it on. I think it will take care of my problem, though.

Assuming the 3.2 pulley just doesnt work out, can i run a 3.3 or 3.4 on the 3.5" tensioner and idler pulleys with the same belt, or will i need to change one or both of them back? Sorry for all the n00b questions!

I tested a few different pulley/belt combos a while back. See page 1 for more info. In addition to those options, a shorter belt would also work. Depends on how often you'll be swapping SC pulleys and if you mind changing belts or not.

The 3.5" idler and tensioner seem to work great with the 3.2" SC pulley. The belt doesnt seem too loose or tight. Yay!

Cool. Be careful with that 3.2" unless you've got some mods we can't see in your sig.

Ok so I just want to be clear on this. and the original photos are no longer available:

Pulleys 1, 2, and 3 are all the same size ( 3" ) and the only difference is if they are smooth or grooved? and pulley number 4 is visually larger, what size is this one? I plan on changing all pulleys and belts soon.

I am 99% sure its a 3.5"

AA wrote:

Cool. Be careful with that 3.2" unless you've got some mods we can't see in your sig.

I will update my sig after the car is started for the first time!  

shoot, so for a 3.25" SC pulley, im gonna need a 3.5" idler and tensioner, huh?

Unless you use a shorter SC belt.

charlieRobinson wrote:

shoot, so for a 3.25" SC pulley, im gonna need a 3.5" idler and tensioner, huh?

The idler is off of a Jeep SOMETHING. I want to say it's a Grand Cherokee. If you're friends with the people at a parts store just have them pull it out and measure it. Let me dig around for a bit and I'll find it. it replaces the front most idler. Going from a 3" grooved to a 3.5" grooved.

Anyone have the part number for the 3.5" SC tensioner pulley?

Part Number: STP-635: http://intense-racing.com/PROD/STP-635.html

or:

Item #: ZZ-6R35SM: http://shop.zzperformance.com/store/p/82-Tensioner-Idler-Pulleys-6rib.aspx

Tyler sent it to me.
Gates 38001 for the 3.5" SC tensioner pulley

TThanks, homie

Whats the part number for the 3.5" idler pulley? I am not seeing it.

AA, will you please post part numbers in the first post of the thread so they are all in 1 place?

Thank you

http://www.amazon.com/gp/product/B001C9BZC0/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

That's the bigger grooved idler that I'm using right now.

matt270avian wrote:

http://www.amazon.com/gp/product/B001C9BZC0/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

That's the bigger grooved idler that I'm using right now.

Gates 36157 Idler Pulley

Nice. Thank you.

Anyone have belt#s for intercooler setups?

ZZP lists the big cars differently than the others so not exactly sure:

http://shop.zzperformance.com/store/p/155-Serpentine-Belts.aspx
667 - Gen 5 blower stock belt GTP/GS/SS supercharged with stock 3.8" pulley (67 1/4" -1708mm)
663 - Gen 3 blower stock belt GTP/GS/SS supercharged with stock 3.8" pulley (66 7/8")
660 - GTP/GS/SS supercharged with 3.3 - 3.7" pulley (66 3/4")
658 - GTP/GS/SS supercharged with 3.2 - 3.6" pulley (66 3/8" - 1687mm)
653 - GTP/GS/SS supercharged with 3.1 - 3.5" pulley (65 7/8")
650 - GTP/GS/SS supercharged with 2.8 - 3.1" pulley (65 1/2")
645 - GTP/GS/SS supercharged with 2.6 - 2.8" pulley

716 - Bonneville SSEi, Park Ave, or Riviera with a 3.4" pulley
721 - Bonneville SSEi, Park Ave, or Riviera with stock supercharger pulley (72 5/8" 1845mm)
(Riviera/Bonneville/Park Ave use same length belts)

Stage 2 or 3 Intercooler
685 - 3.3"+
680 - 2.90" - 3.20"
675 - 2.6" - 2.8"