View Full Version : Idler vs Tensioner pulley size

Les Borda
07-17-2014, 06:59 PM
One is larger, 2 are smaller, no clue anymore which is called what. The Haynes manual is useless for this it shows nothing about idler or tensioner pulley.

I know Fast Ed got me Mustang pulleys when I had the XR7 they were a little wider, all steel and fit perfect but I also had a 10% charger overdrive pulley on.

Right now with no overdrive supercharger pulley it may be a tight squeeze getting that belt on, I think the Stang ones were a larger diameter

Nonetheless I want to dump those plastic pulleys for steel. Any help or part numbers like from RockAuto.com if you recognize the correct ones would be appreciated. They list them as tensioner pulley and idler pulley as separate.

Dayco, Goodyear, AC-Delco, Motorcraft as long as they are not plastic, and if you have done this did you need any kind of spacer or washer?

Getting older just sucks from a memory perspective not to mention other things

Les Borda
07-17-2014, 08:50 PM
Thanks guys the light bulb went on I got 3x76mm Stang ones from Ed

Bill at SC Perf has a 3 pack of 76mm steel ones for $52.97, I can't beat that price even on rockauto.

Bit of a biatch using a 76mm on a stock blower pulley but according to Bill it works, and that sets up the 10% blower overdrive when it gets done.

07-17-2014, 09:06 PM
I went 10%, with a 5% aluminum sc pulley and 5% aluminum js pulley, but since one went larger and one went smaller, it was a wash and a stock SC/JS belt fit fine. 77mm idler pulleys all around.

Les Borda
07-17-2014, 09:28 PM
If those damned JS pulleys weren't so pricey it;s a good way to go 5% and 5%. I don;t get why the 5% OD pulley for the blower is more than the 10 at SC Perf.

Found another site called Pulley Boys, all kinds of blower od's and yepper there it was Eaton M90 pulleys for Coupes. Cool thing is you select your diameter, anything 2.7 and under they tell you that the nose on the blower has to be machined down. 80 bucks, ok it's black not polished not a big deal. The 2.8 size is a little over 10% and the 2.9 size is a little under. They have a 3.0 I think that is stock on 89-93.

07-17-2014, 09:47 PM
I snagged a Pulley Boys aluminum black 5% sc pulley off a donor in one of the local junk yards for $12.50 - w/that and a 5% ai js pulley I see 14 lbs boost on my Anny. I bought a stock diameter water pump aluminum pulley from Victor/SpinningWheels.

Les Borda
07-17-2014, 10:04 PM
I like the aluminum stuff. When the Ontario Chapter was going hot and heavy, back when I had my XR7, Ryan Harris lived in Toronto and was a machinist. He made us JS pulleys,alternator pulleys, crank pulleys, it was great. Reasonable prices too.

07-17-2014, 10:20 PM
I think my 5% js ai pulley is one of his.

Les Borda
07-18-2014, 06:51 PM
I miss Ryan Harris we used to have a blast doing stuff at his Dad's place, helping Ryan part out quite a few birds and XR7's. He was always willing to help one of us out working on things.

Just a few days ago he provided me with just the speedo from a 90, the odo gears were garbage on the 90 my son bought. This one when I took it apart the gears were ace.

By the way Bill at SCPerf had a deal on if you buy 3x76mm steel idlers, something like $54.95 for 3 I couldn't beat that price even at rockauto.

Greg Coleman
07-20-2014, 06:55 PM
maybe next year i will get nickeys car going now that i have changed jobs but would sell them if anyone is interested

Les Borda
07-20-2014, 09:58 PM
I;d be afraid to ask what you'd want for your XR7, dinged in door or not LOL, I bet it;s still pristine

333 RWHP DAYUM brother, impressive

Ok I have got to bring this up, do you remember the night we finished up doing some major mod to the Cougar and I forget what it was. You and I took her for a test drive , came back and FREAKED that she was about to boil over. LMAO we were looking at the wrong gauge, GOD that was funny!!!!!!!!!!!!!!!!!!!!