Belt size for 2.76 and 4 idlers, two sources

[finaliize]

I have a 4 piece set of BF idlers sitting in the garage awaiting my BF 2.76 upper pulley to come in the mail in a few weeks. Now I know reading the title you are immediately going to refer me to shangshiftergaskets.com which I did read, and the recommended belt size for a 2.76 with the 4 piece set is 74.5 or 75.

Now I was researching prices and went to the official billetflow website and they want

2.76..............75.1".................K080751...............4080750 (with 100mm Idler) (Stock Belt)

75.1.. stock belt?

I'm not sure on the stock belt size for the 03-04 Cobra's but i'm not very confident that i'd be able to use the stock belt after installing these 5 pullies.. am I wrong? Or is billetflow incorrect. I don't want to screw up the installation with the wrong parts. I had a 2V before this so this is all new to me.

 

[SVTLink]

This may help.

Belt Selection Guide

 

[finaliize]

Thats the site I used, but thank you for linking because I missed the initial paragraph up top when I was in a rush that specifically tells you the stock size is 75.1, so I won't be needing a new belt with the 4 piece idler set, great news. Thanks.

 

[lowflyn]

Did you buy the upper idler brand new from bf? The old mount design will lead to a different belt size, as long as the products are new you will be fine with the factory belt.

 

[SVTLink]

Hahah. That's exactly what I did. I'll check my car in the morning some I have same setup on mine

 

[03cobra#694]

75.1 stock or a 74.5

 

[timspony]

I have a 2.76" upper with 4 - 90mm idlers and I'm running a 74" belt if that helps!


(74.5" with a 2.93" upper)

 

[finaliize]

Did you buy the upper idler brand new from bf? The old mount design will lead to a different belt size, as long as the products are new you will be fine with the factory belt.

I'm not sure if it's the old mount or new mount, I bought the Cobra in July and the previous owner gave me the idlers and mount in a bag, they were never installed, but i'll check if there is any paperwork in the bag. They are the 3 100mm and 1 92 mm I believe.

 

[101blur]

I'm running a stock belt.

 

[matt87]

i have the same setup. i have a 2.76 bf upper and the 4 piece pulley setup. i had a gates 76" inch belt but it started chirping badly after a short while. i replaced it with a dayco gold 75" belt but it was so tight i had to remove the stop on the tensioner and change the 100mm aux idler to a 90mm. now its tight as hell and no slip.

 

[*SVT*]

I have a BF 2.76 & 100mm idler. The rest is stock. With a stock belt I was loosing 4lbs of boost at 6,000 RPMs. I took a chisel and snapped the little tab off of the tensionser that stopps you from pushing it so far. I was able to get a Gates 4080740HD on there. Now I only loose 2lbs of boost at 6,000 RPMs.

 

[Bdubbs]

Stock belt will work. Or you can try a 74.5. I have a 2.8 pulley and I have a 74.5" gates belt.

 

[01Jes]

I have a BF 2.76 & 100mm idler. The rest is stock. With a stock belt I was loosing 4lbs of boost at 6,000 RPMs. I took a chisel and snapped the little tab off of the tensionser that stopps you from pushing it so far. I was able to get a Gates 4080740HD on there. Now I only loose 2lbs of boost at 6,000 RPMs.

No shit, gonna have to check mine out. My setup is similar. Well almost I have 3 BF 92MM and 1 100MM BF. I'm using the stock belt as well.

 

[Grimster]

I put a new Gates belt on after I got my 2.76 and idlers installed. Stock size. works great with no boost loss. I sit right at 14-14.5lbs.