So what is actually the factory upper and lower size?

Sal has stated before 7.5 and on a way older post I seem him state 7 and 5/8 (7.625). I see him state 3.0 for the upper.

Speedin Bob has an Excel spreadsheet made up and in it he uses 2.926 for the factory upper, and 7.401 for the factory lower.

Bob, are you measuring the OUTSIDE of the grooves where you're suppose to? Or did you get these #'s from someone else?

2.926 vs. 3.0 will change the pulley rpms by nearly 500 at 5,500 engine rpms. That's quite a bit of a big difference, so that's why I'm curious.

If anyone has a stock lower and possibly a stock upper laying around could you measure w/ a measuring tape around the outside of the grooves for us? I would greatly appreciate this!

Thanks guys!

BfB

 

I measured my stock lower and it looks like 7.4

 

AHHHH, sure is!

so it's either 23 and 5/16 or 3/8 'eh? How close to 3/8 than 5/16?

If it's 23-5/16 than that is: 7.42
If it's 23-3/8 than that is: 7.44

Using 3.141592653589793 for pi.

NOW, the big question is, what is the factory upper exactly? This might really throw things for a loop by a couple hundred to few hundred rpms.

Someone measure me the stock upper and I'll tell you why! Loosen your belt if you have to.

Bubba

 

BFB

I didn't measure them myself. Rather, the stock measurements were obtained from various threads on this topic from this and other forums. Measurements are to the top of the grooves if I'm not mistaken.

***disclaimer***
The sheet is an INFORMATIONAL TOOL ONLY, not law according to yours truly. Simple math actually.

AND.... I've stated in each reply requesting this sheet that it is best to confirm pulley sizes with your tuner of choice.

The smaller numbers were used as they have a direct effect on the Blower RPM at shift point(s) for which I am concerned, rightly or wrongly. (read: daily driver, reliablility a must)

I'd rather be a tick slower and reliable than grenading the blower, engine, etc. on a spirited run during a daily commute.

Bob

 

The pulley that Metco uses to represent the stock one is a 293. 'Dont know if this is correct though.

 

I have measured 2 stock upper pulleys and they were both 2.926, the stock lower pulley was 7.401 and the PSP pulley was exactly .500 larger at 7.901.

I have not measured any other pulleys so far, but I think JL said his 3lb pulley was 8.220, but am not sure how it was measured.
All of my pulley measurements were over the grooves with a micrometer.
Dale

 

Here's JL's email to me:

stock 7.455 .092 over gauge *****
3#- 8.227 .092 over gauge *****
4#- 8.99 .092 over gauge *****
5#- 9.762 .092 over gauge *****
6# 10.534 .092 over gauge *****

Damn, those are some big pulleys

BfB

 

Somebody is smokin' some bad chit....here is my take on the 3&4......3 is 8.220 4 is 8.470

 

Jeff, if his latest email to me is an accurate measurement of his 4# and higher pulleys then here is what I come up with:

[code]
3# 4# 5# 6#
Pulleys: STK(7.4) JDM(7.8) PSP(7.9) METCO(8) JL(8.17) JL(8.94) JL(9.71) JL(10.48)
Price : $239 $240 $249 $260 ? ? ?

ENG. Blower RPMs
RPMS
5000 - 12645 13329 13500 13671 13396 15277 16593 17908
5100 - 12898 13595 13770 13944 14240 15582 16924 18267
5200 - 13151 13862 14040 14217 14519 15888 17256 18625
5300 - 13404 14129 14310 14491 14799 16193 17588 18983
5400 - 13657 14395 14580 14764 15078 16499 17920 19341
5500 - 13910 14662 14850 15038 15357 16805 18252 19699
5600 - 14162 14928 15120 15311 15636 17110 18584 20057
5700 - 13404 15195 15390 15584 15916 17416 18916 20416
5800 - 13657 15461 15660 15858 16195 17721 19247 20774
5900 - 13910 15728 15930 16131 16474 18027 19579 21132
6000 - 14162 15995 16200 16405 16753 18332 19911 21490
[/code]

Okay, here's what I went and did. I took JL's #'s he sent me in email and figured in he was over calculating the stock pulley by .054 because 2 people now have measured the stock pulley as 7.400 (JDM) and 7.401 (Bad as L).

I then just said 7.4 for factory since it is so close (.001) to make it an average point to work with. Since Bad as L states he measured Sal's pulley EXACTLY .5 larger to 7.901 I figured it as 7.9, again since it's so close. JDM states EXACTLY .4 larger to 7.8 (and he measured 7.400 and 7.800). Johnny is getting a larger # for stock somehow (gauge is off I assume, but maybe not), so I just downsized the rest of his pulley #'s by taking the difference between his stock pulley measurement and Bad as L's, and then subtracting from JL's published #'s.

I emailed again to make sure he sent me the right #'s this time. He originally emailed me 8.454 for his 4# pulley, but emailed you

...yet in his last email he's now measuring the 4# as 8.99.

Hopefully we'll get to the bottom of this.

BfB

 

The 8.47 number looks correct on the 4#. I layed Jim's 2# over the top of it and I would say it was about .67" bigger.

 

Now, I'm REALLY confused.

Why would JL keep emailing different #'s then? JL, you there?

LTNBOLT, do you have access to some accurate dial calipers? A machine shop would if you know any around there. It would really help if you could get the #2 and the #4 measured as well as your stocker (that way we can stay uniform in the differences).

BfB