BBK U/D pulley belt size, not stock?

[94-302-vert]

I jsut finished putting in my bbk steel U/D pulleys. I had jsut the alt pully on then had to wait on the crank and WP pulley until I got the right WP for my car (the WP pulley was totally different).

Put on the stock belt and it is WAY too long... So I had a belt I bought when I was trying to run my U/D crank pulley and my U/D alt pulley and this is also marginally too long. It is a brand new Dayco 6PK2615 (103"?).

Since I obviously can't drive the stang to the store and I don't want to cut my streteched out stock belt JIC I have cooling issues and need to go back to the factory pullies any one know what belt I need.

I am thinking of getting something 2" and 4" shorter than the 6PK2615.

Anyone else go through tis and what belt did you use?

Thanks,
Chris

 

[grngt50]

that sounds odd.........I have the exact same pulley set and my stock belt fits just as snug as when it was wrapped around the stockers. Alot of guys on here have just wrapped a piece of string around the pulleys and then measured the final length to get the approximate belt size. Good luck man

James
94 GT VERT AODE
Ported stock intake, 4.10's, shift kit, Granatelli MAF, BBK 70mm TB, 14*, BBK adj fpr, 2 chamber flows, BBK O/R H pipe, BBK underdrive pulleys, MSD 6A, Walbro 190 pump, k&n with silencer removed, sub-frame connectors, fan switch mod, 160* tstat , weight reduction

 

[18mustangs]

I ahve the BBK aluminum underdrive pullies and my stock belt fit just fine. I don't mean to ask the obvious, but are you sure that you routed the serpentine belt in accordance with the diagram?
Tim

 

[94-302-vert]

Yep, really only one way to route them...

I jsut got back from buying the shorter belts... as soon as my son falls asleep I'll see if either one fits...

Chris

 

[94-302-vert]

The 101" was perfect... Now what is the stock length is it supposed to be 105"?

I wonder if I had problems because my car is an early 1994...

 

[94MustangGT5.0]

I can't believe that a different alt. pulley made a that much of a difference in length. You said that the WP pulley is completely different, but I just want to make sure that you know that a underdriven WP pulley is much bigger than the stock one, and the underdriven crank pulley is much smaller than the stock one. So, if you simply took the WP pulley off and stick the underdrive one on with out taking off the stock crank pulley, it would not work because they would hit. You must take the crank pulley off also, or simply put the crank pulley on first. I am not trying to say that you don't know what you are doing, I just want to make sure you understand how these pulleys work. If this wasn't your problem, then what was the problem with the WP pulley? I am assuming you bought a kit with all of the pulleys in it? Good luck.

 

[fushnicken]

I have BBK aluminum under drives on my SN95. No problem with the stock belt at all. The belt tensioner arrow fell withing the acceptable range markings on the tension's face.

Not that this should matter, but it might. I still have A/C, PS and the smog "air" pump installed.

It is possible to misroute the belt and make it appear like it can't fit. I did that at first. Eventually, I got the correct route and the stock belt fit just fine.

 

[fushnicken]

Sometime a little RTFM (Read The F-ing Manual) helps. It helped me in this case.

 

[94-302-vert]

Yep, with jsut the alternator pulleys and the non-U/D crank and WP pulleys i was able to squeeze my stock belt on which then strettched ot where it was OK.

Then after the install of the BBK U/D crank (smaller) and U/D WP (bigger) pulleys the stretched stock belt was way too big, the smaller than stock belt i had was close but still loose then I ended up using a 101" belt.

Go figure.

Thanks Guys.
Chris