The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1967 - 1972 Chevrolet & GMC Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 12-21-2015, 12:36 PM   #1
Mrturner1
Registered User
 
Join Date: Nov 2015
Location: Colfax California
Posts: 1,644
Aftermarket crank pulley smaller than OE?

I got a couple pulleys to dress up the front of the engine a little, and the crank pulley is smaller than the original. Is this going to cause a problem?
Mrturner1 is offline   Reply With Quote
Old 12-21-2015, 07:07 PM   #2
Mrturner1
Registered User
 
Join Date: Nov 2015
Location: Colfax California
Posts: 1,644
Re: Aftermarket crank pulley smaller than OE?

Anybody?
Mrturner1 is offline   Reply With Quote
Old 12-21-2015, 07:43 PM   #3
midniteblues
Registered User
 
midniteblues's Avatar
 
Join Date: Jul 2011
Location: strausstown pa
Posts: 3,394
Re: Aftermarket crank pulley smaller than OE?

They should work fine as long as all the grooves line up with the old pulleys.

A smaller diameter crank pulley might speed up the other pulleys depending on there size. But you'll never notice the differnce.
__________________
81 camaro 355 4/spd 342 posi my first love.
67 swb step 454/4spd ott 373 posi 4/7 drop.
2000 s10 zr2 little blue truck that never gets stuck.
'74 heald super bronc vt8. tecumseh powered moon rover.
midniteblues is offline   Reply With Quote
Old 12-21-2015, 07:44 PM   #4
tdangle
Senior Member
 
tdangle's Avatar
 
Join Date: Mar 2005
Location: Jurupa Valley, Ca
Posts: 1,209
Re: Aftermarket crank pulley smaller than OE?

Your accessories will run slower than with the stock crankshaft pulley. The rule is larger accessory puller the slower the accessory will run, conversely the smaller the crankshaft pulley the slower. You can do the math if you want, it is a matter of ratios between the drive pulley and driven pulleys.
__________________
Terry

1970 Custom Camper/C20 , GM Crate 350/7004R, Dana 60, factory AC
tdangle is offline   Reply With Quote
Old 12-21-2015, 07:47 PM   #5
hamjet
Registered User
 
hamjet's Avatar
 
Join Date: Apr 2013
Location: South Westerlo, New York
Posts: 1,325
Re: Aftermarket crank pulley smaller than OE?

I gave wrong advice........................
__________________
Thanks, Joe..
1969 C/10, 348 C.I., 3X2 bbl. V8, 2004r , LWB.

Last edited by hamjet; 12-21-2015 at 09:48 PM.
hamjet is offline   Reply With Quote
Old 12-21-2015, 09:33 PM   #6
swamp rat
Registered User
 
swamp rat's Avatar
 
Join Date: Oct 2007
Location: Spanaway
Posts: 8,451
Re: Aftermarket crank pulley smaller than OE?

Nope, a smaller pulley equals less surface on the diameter of the pulley, less surface means a slower belt and accesorys turn slower
__________________
Mike.

Swamp Rat build thread :
http://67-72chevytrucks.com/vboard/s...d.php?t=595019

72 3/4T 4X4
4" BDS Lift
33" BFG's
swamp rat is offline   Reply With Quote
Old 12-21-2015, 09:46 PM   #7
hamjet
Registered User
 
hamjet's Avatar
 
Join Date: Apr 2013
Location: South Westerlo, New York
Posts: 1,325
Re: Aftermarket crank pulley smaller than OE?

Quote:
Originally Posted by swamp rat View Post
Nope, a smaller pulley equals less surface on the diameter of the pulley, less surface means a slower belt and accesorys turn slower
You are correct, where is my brain tonite....
__________________
Thanks, Joe..
1969 C/10, 348 C.I., 3X2 bbl. V8, 2004r , LWB.
hamjet is offline   Reply With Quote
Old 12-21-2015, 09:46 PM   #8
trac209
Registered User
 
Join Date: Dec 2011
Location: winnipeg
Posts: 1,107
Re: Aftermarket crank pulley smaller than OE?

Quote:
Originally Posted by swamp rat View Post
Nope, a smaller pulley equals less surface on the diameter of the pulley, less surface means a slower belt and accesorys turn slower
reread that you're correct,but only if you're talking main pulley diameter. If the accessories pulleys are larger it slows them down
trac209 is offline   Reply With Quote
Old 12-22-2015, 08:42 AM   #9
midniteblues
Registered User
 
midniteblues's Avatar
 
Join Date: Jul 2011
Location: strausstown pa
Posts: 3,394
Re: Aftermarket crank pulley smaller than OE?

Thinkin an typing don't work sometimes.
it will slow it down the belt.
But like I said you won't notice it.
__________________
81 camaro 355 4/spd 342 posi my first love.
67 swb step 454/4spd ott 373 posi 4/7 drop.
2000 s10 zr2 little blue truck that never gets stuck.
'74 heald super bronc vt8. tecumseh powered moon rover.
midniteblues is offline   Reply With Quote
Old 12-22-2015, 08:49 AM   #10
hamjet
Registered User
 
hamjet's Avatar
 
Join Date: Apr 2013
Location: South Westerlo, New York
Posts: 1,325
Re: Aftermarket crank pulley smaller than OE?

Worst case is if the RPMs are low at idle and some accesories like heater fan or head lites on you might see the alternator light flicker if you have idiat lite or the needle might show discharge on a gauge..
__________________
Thanks, Joe..
1969 C/10, 348 C.I., 3X2 bbl. V8, 2004r , LWB.
hamjet is offline   Reply With Quote
Reply

Bookmarks


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 07:12 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com