underdrive pulley question?

stang_guy_95 · 04-24-2003, 11:48 PM

I just recently bought some underdrive pulleys and I noticed that the crankshaft pulley was significantly smaller but the water pump pulley was much bigger. Did they do that so that I would be able to use the same belt. Also, will it be better as far as performance to just use my smaller stock water pump pulley, or is it bigger for a reason. Please help me out here. Thanks guys.

MEDIK418 · 04-25-2003, 01:27 AM

This is correct. THe alternator pully is also a different size in order to use the stock belt.

HiFlow5 0 · 04-25-2003, 02:14 AM

Underdrive pulleys are suppose to slow down the movement of all the accesories, while making the crank shaft spin at the same speed if not more. The larger water pump and alt pulleys slow down their cycle as they spin while the crank pulley is spinning much faster cause of it's smaller diameter pulley. This gives the crank shaft less resistance while the motor is running.

stang_guy_95 · 04-25-2003, 08:44 AM

Thanks for the help guys. Should I use the stock water pump or the bigger one that came with the u.d. pulley kit, or will it really affect performance?

MEDIK418 · 04-25-2003, 12:40 PM

I've got two sets of pulleys installed and haven't noticed any problems with the cooling. Both have stock water pumps. One with a 3 row radiator, the other a stock two row.

82 GT · 04-25-2003, 07:35 PM

What about charging problems? Did you experience any of that or do you have a 3G alternator?
Is there a difference that you can actually feel? I'm just curious.

82 GT · 04-25-2003, 07:38 PM

Hey Medik,

I just looked at your signature. Where is that mustang with the 351C in it? Did you sell it?

04-24-2003, 11:48 PM	#1
stang_guy_95 Registered Member Join Date: Jul 2002 Location: michigan Posts: 56	underdrive pulley question? I just recently bought some underdrive pulleys and I noticed that the crankshaft pulley was significantly smaller but the water pump pulley was much bigger. Did they do that so that I would be able to use the same belt. Also, will it be better as far as performance to just use my smaller stock water pump pulley, or is it bigger for a reason. Please help me out here. Thanks guys.

04-25-2003, 01:27 AM	#2
MEDIK418 Registered Member Join Date: Mar 1999 Location: Amarillo, Texas, USA Posts: 780	This is correct. THe alternator pully is also a different size in order to use the stock belt. __________________ 1986 four-eyed LX coupe, 358 Cleveland, Tremec TKO600/centerforce clutch, dish cut Probe forged pistons, comp cams hyd.roller cam, .579/.588@224/230, Edel.performer, 670 holley street avenger, CPR custom built long tubes, ported and polished 4bbl heads, manley valves, beehive springs, MSD peo-billet dist/MSD6AL, fluidamper, 5 lug conv. with 17x8 bullits there's more but it's still not finished yet. Oh, and the oldest boy is turning his 89 GT into a FFR cobra this next summer.

04-25-2003, 02:14 AM	#3
HiFlow5 0 Registered Member Join Date: Mar 2000 Location: Springfield, Ma, usa Posts: 706	Underdrive pulleys are suppose to slow down the movement of all the accesories, while making the crank shaft spin at the same speed if not more. The larger water pump and alt pulleys slow down their cycle as they spin while the crank pulley is spinning much faster cause of it's smaller diameter pulley. This gives the crank shaft less resistance while the motor is running. __________________ NewEngland Auto www.baystategearheads.com -91 Mustang Coupe, ex 4cyl (sold) -99 F150, 3" lift, 35" Procomps, Magnaflow exhaust

04-25-2003, 12:40 PM	#5
MEDIK418 Registered Member Join Date: Mar 1999 Location: Amarillo, Texas, USA Posts: 780	I've got two sets of pulleys installed and haven't noticed any problems with the cooling. Both have stock water pumps. One with a 3 row radiator, the other a stock two row. __________________ 1986 four-eyed LX coupe, 358 Cleveland, Tremec TKO600/centerforce clutch, dish cut Probe forged pistons, comp cams hyd.roller cam, .579/.588@224/230, Edel.performer, 670 holley street avenger, CPR custom built long tubes, ported and polished 4bbl heads, manley valves, beehive springs, MSD peo-billet dist/MSD6AL, fluidamper, 5 lug conv. with 17x8 bullits there's more but it's still not finished yet. Oh, and the oldest boy is turning his 89 GT into a FFR cobra this next summer.

04-25-2003, 07:35 PM	#6
82 GT Import Slayer Join Date: May 1999 Posts: 2,241	What about charging problems? Did you experience any of that or do you have a 3G alternator? Is there a difference that you can actually feel? I'm just curious. __________________ '82 GT 351W (.060)Comp Cams 274* Extreme Energy cam, ported & polished heads w/ 1.94/1.60 valves 10.3:1 flat top pistons,stealth intake, Mallory dizzy,Holley 750dp carb, BBK shorties,Flowmaster exhaust,C-4 with 3700 stall converter, B&M pro shifter,8.8 rear, 4:10's, subframes, electric fan, powermaster alternator, 4 core radiator.

04-25-2003, 08:44 AM	#4
stang_guy_95 Registered Member Join Date: Jul 2002 Location: michigan Posts: 56	Thanks for the help guys. Should I use the stock water pump or the bigger one that came with the u.d. pulley kit, or will it really affect performance?

04-25-2003, 07:38 PM	#7
82 GT Import Slayer Join Date: May 1999 Posts: 2,241	Hey Medik, I just looked at your signature. Where is that mustang with the 351C in it? Did you sell it? __________________ '82 GT 351W (.060)Comp Cams 274* Extreme Energy cam, ported & polished heads w/ 1.94/1.60 valves 10.3:1 flat top pistons,stealth intake, Mallory dizzy,Holley 750dp carb, BBK shorties,Flowmaster exhaust,C-4 with 3700 stall converter, B&M pro shifter,8.8 rear, 4:10's, subframes, electric fan, powermaster alternator, 4 core radiator.

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