Whipple idler pulley?

[Gabe]

I need help finding the right pulley to replace an idler pulley on my 2.3 Whipple/Ford Racing kit.
It is 76mm in diameter, but since I'm going down in blower pulley size I'm open to the idler being as big as 80-82mm in diameter. Original blower pulley was 3.375", currently using a 3.24", going to a 3.125" soon.
Whipple and Roush have been no help.
(most of the kit is Roush, except the head unit)

I'm looking to replace the pulley in the pics and video below.
I found one on Amazon (and other sites), but I want something beefier.
The one on Amazon: Amazon.com: Motorcraft YS245 New Idler Pulley for select Ford/ Lincoln/ Mercury models: Automotive

Anybody have any ideas?

Thanks in advance.
(oh, and I need a new belt too, where do I get one of those, and which size?)

 

[stkjock]

http://www.thumpracing.com/idler_pulleys.htm

 

[eighty6gt]

https://www.rockauto.com/en/moreinfo.php?pk=961372&cc=1441223&jsn=3

I have a Roush M90 kit, used these guys. I believe it's a 2003 cobra part, I'm sure among other things.

 

[skwerl]

The idler pulley just down from the blower just barely deflects the belt, so changing sizes there isn't going to take up the belt slack from a smaller blower pulley. You need to upsize an idler with more belt wrap, perhaps the tensioner pulley.

As far as belt length, measure it. Take it off, mark it and then run your tape measure all the way around back to your starting point. Most belt sizes are listed with the number of ribs, a dash and the length in inches. Example would be 06-0137 for a six rib 137 inches long. There are variations but you can usually decode the part numbers fairly easily.

 

[Gabe]

Thanks guys.

The Ford Racing book that came with the blower kit lists only one belt, part # K060825 which I'm finding to be 83 1/8" long
I'm thinking going with a stock-size pulley and an 83" belt should be fine?
Thoughts on that?

That same list also shows the part # for the pulley, 953045.

On the belt on the car, I see RS-2 1513MX but I don't think that's a part #

 

[stkjock]

K060825 That belt should be 82.5" effective length

The numbers tell you ribs and length.

 

[skwerl]

Look at the amount of travel in your tensioner. There will usually be an indicator with an acceptable range of travel. You want to size your belt and pulleys so the indicator is within the acceptable range. Without seeing that, all suggestions will be merely guesswork.

 

[skwerl]

Searching your belt number on google the very first hit was this:
Amazon.com: Gates K060825 Multi V-Groove Belt: Automotive

 

[Gabe]

K060825 That belt should be 82.5" effective length

The numbers tell you ribs and length.

Yeah it comes up as 82.59" effective length, 83.155" outside diameter

Look at the amount of travel in your tensioner. There will usually be an indicator with an acceptable range of travel. You want to size your belt and pulleys so the indicator is within the acceptable range. Without seeing that, all suggestions will be merely guesswork.

Thanks, I will have to do that.

Searching your belt number on google the very first hit was this:
Amazon.com: Gates K060825 Multi V-Groove Belt: Automotive

Yeah, I found that too, but I want something beefier.
Looking into the Gates Racing blue belt, K060825RB, same size but a much beefier belt

 

[travelers]

Look at the amount of travel in your tensioner. There will usually be an indicator with an acceptable range of travel. You want to size your belt and pulleys so the indicator is within the acceptable range. Without seeing that, all suggestions will be merely guesswork.

Skwerl is right as to the measurement. You are only going smaller by 1/8'' in diameter, so I would look at where the tensioner is. You may not have to change belts at all. If you do it shouldn't be much. I have the same setup you do except I'm still using the 3.75 pulley. If you change the idler 1/8" or 0.125 = 3.175mm so a 80mm idler might be all you need

 

[Gabe]

Well, I ordered the Thump Racing 76mm double-bearing idler.
Ordered it from Lethal Perf.
Between the 5% coupon code I used and my loyalty points, it ended up being about $122.

Tried using coupon code DARREN but apparently they don't have it set up yet.

I'm thinking I'll install the new idler and blower pulleys and check the belt slack.
Then if it's OK, I'll just order the same-length Gates Racing blue belt and install it then.
Kinda sucks to do the job twice, but don't want to order parts that I might have to return, so whatever ...

 

[eighty6gt]

Like, Darren Darren? His idlers haven't got bearings - they are just painted wood. Is he still around?

 

[Gabe]

Like, Darren Darren? His idlers haven't got bearings - they are just painted wood. Is he still around?

Lol yeah, that troll.
And luckily he seems to have taken the hint and left

 

[Gabe]

Got the Thump idler installed.
Was surprised that the boss it sits on only goes half-way through it, so the double-bearing pulley only has the inner bearing sitting on something.
I wonder if I that's gonna be OK.
Also, it's made to work with 6-rib and 8-rib belts, according to Lethal's site, but it looks odd since it's much wider than the 6-rib belt I'm using.
Thoughts?

 

[stkjock]

bang some gears and see!

I see no issue

 

[Gabe]

bang some gears and see!

I see no issue

I drove the car around the block and it seemed fine, but just re-checked Thump's and Lethal's websites, they both list the same exact info (obviously Lethal just lists the info on Thump's site), and the pulley was supposed to include a stepped bushing and a new mounting bolt.

So for now I put the factory pulley back on until I get the missing parts mid-week next week.

I seem to have plenty of travel left in the tensioner though, so at least the belt should not need to be replaced when I install the new smaller blower pulley

 

[Gabe]

I would've thought the Thump pulley would spin more freely.
Is it normal for it to have this much drag?

 

[eighty6gt]

Lol yeah, that troll.
And luckily he seems to have taken the hint and left

A lot of people have left.

My gates idlers spin free.

 

[travelers]

Does that have 2 bearings? If so try holding each one separately and spinning it.

 

[Gabe]

Yeah, 2 bearings.
Just tried it, it's the same, lots of drag.
Sent an email to Thump Racing earlier with a link to the video, wondering if it's normal or not.
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