Pulley size ? on cooling

-
go-fish

go-fish

FABO Gold Member
FABO Gold Member
Joined
May 20, 2010
Messages
2,751
Reaction score
4,434
Location
Okla.
I need pulleys. I am looking for a single groove crank and aluminum water pump pulley. I have been considering the CVF aluminum pulleys from Mancini but the size is not stock. Do they have an ill effect on cooling? Should I stick to looking for OEM pulleys for the best cooling?

OEM w/p pulley = 6-7/8"
CVF w/p pulley = 6-3/8"

OEM crank = 6-9/16"
CVF crank = 5-1/4"

Is this enough difference to matter?

Using a high flow w/p and also using an ATI damper. Will that have an affect on crank pulley spacing? Any alignment issues using the Denso brackets and alternator? Alternator is from a '91 D150 (two groove pulley but will switch for single grove).

I've been trying to find used pulleys but no dice yet so I have been getting closer an closer to just buying either style from Mancini, which sells the CVF billet and Bouchillon OEM pulleys. They are very comparable in price but I do like the look of the billet pulleys slightly better. Honestly, I don't like them so much better than to not get the best set for cooling though. If the OEM's are even slightly better at cooling then I'll go that route.

Thanks to you pulley and cooling gurus for helping out with my stupid questions.
 
Rat Bastid said:
Call CVF and tell them you do NOT want under drive pulleys. They have them. Dont slow the water pump down.
Click to expand...

Okay, so those CVF's sold by Mancini are definitely a no-go. CVF's site lists the same ones. Are the CVF non-underdrive pulleys on a secret shelf at the warehouse? I'll give them a call though.

Or the hell with it if they don't exist and get OEM's.
 
Rat Bastid said:
you do NOT want under drive pulleys
Click to expand...
Did that with a street driven stroked 340 (372) using March pulleys. It ran hot in heavy traffic.Had to pop it in neutral and keep the rpm's up.Went back to stock and all was fine.
 
It's all on the ratios.

Stock

Wp = 6.88
Crank = 6.56
5% under driven

CVF
Wp = 6.38
Crank = 5.25
21% under driven

PLUS With a crank pulley that small the alternator pulley will be reduced in speed
From overdriven by 62% to overdriven by only 52%

That's like putting a 3 to 3.25 pulley on the alt with the OEM crank pulley. You will have crappy charging at idle, If any. At 600 rpm crank you alternator will only be spinning at about 900 RPM.
 
Dana67Dart said:
It's all on the ratios.

Stock

Wp = 6.88
Crank = 6.56
5% under driven

CVF
Wp = 6.38
Crank = 5.25
21% under driven

PLUS With a crank pulley that small the alternator pulley will be reduced in speed
From overdriven by 62% to overdriven by only 52%



That's like putting a 3 to 3.25 pulley on the alt with the OEM crank pulley. You will have crappy charging at idle, If any. At 600 rpm crank you alternator will only be spinning at about 900 RPM.
Click to expand...


It depends on the year and the engine. Many were overdriven by quite a bit.

The rule is never underdrive a water pump. Unless you are shifting at 8k or more. Then it may throw the belt or explode the fan (or both) if you run a mechanical fan.
 
Rat Bastid said:
It depends on the year and the engine. Many were overdriven by quite a bit
Click to expand...
All I was doing was comparing the ratios of the OEM vs aftermarket. My assumption was the OPs "OEM" dimensions were what were in his car now.
 
When I went through this, I couldn't seem to find any post '70 SB single v-groove overdriven pulley set, even from CVF, March, etc. Seems like all of the overdriven sets out there are for A/C applications with a million groove crank pulley and super shallow w/p pulley.
 
mopowers said:
When I went through this, I couldn't seem to find any post '70 SB single v-groove overdriven pulley set, even from CVF, March, etc. Seems like all of the overdriven sets out there are for A/C applications with a million groove crank pulley and super shallow w/p pulley.
Click to expand...


CVF has them. You have to call them. IIRC to do it one is actually a big block pulley. I’ve asked them to put a part number on it but they told me no one ever asked for them but me.
 
Rat Bastid said:
CVF has them. You have to call them. IIRC to do it one is actually a big block pulley. I’ve asked them to put a part number on it but they told me no one ever asked for them but me.
Click to expand...

I've called and spoke to a couple different guys there. Everyone I spoke to said they do not carry a single v-groove set that'll overdrive the w/p for a small block Chrysler. I think they sell a serpentine belt setup that does though.
 
mopowers said:
I've called and spoke to a couple different guys there. Everyone I spoke to said they do not carry a single v-groove set that'll overdrive the w/p for a small block Chrysler. I think they sell a serpentine belt setup that does though.
Click to expand...


I’ll see if I can find my receipt tonight and post the part numbers. I’m pretty sure they itemized each pulley.
 
Rat Bastid said:
I’ll see if I can find my receipt tonight and post the part numbers. I’m pretty sure they itemized each pulley.
Click to expand...

That would be awesome! When I called them, they said they only carry the "high flow" v-groove set with a single groove w/p pulley, and a double groove crank pulley. I guess one could chuck the crank pulley up in a lathe and cut the outer groove off. Even then, their "high flow" set is still just 1:1.
 
Last edited:
I think I have it solved! Thanks @Rat Bastid , I gave CVF a call and they pointed me to the High Flow pulley on their site. It is just the 2 groove crank pulley. I guess if I ever want to put power steering on the car I would have the extra groove. I do wish they made the same size crank pulley in single groove though.

  • 1 Groove Water Pump Pulley (SCRL1WP) = 6.4"
  • 2 Groove Crank Pulley (SCRL2CR) = 6.4"
  • 1:1 ratio
Chrysler Small Block Crankshaft Pulley 2V - High Flow
 
go-fish said:
I think I have it solved! Thanks @Rat Bastid , I gave CVF a call and they pointed me to the High Flow pulley on their site. It is just the 2 groove crank pulley. I guess if I ever want to put power steering on the car I would have the extra groove. I do wish they made the same size crank pulley in single groove though.

  • 1 Groove Water Pump Pulley (SCRL1WP) = 6.4"
  • 2 Groove Crank Pulley (SCRL2CR) = 6.4"
  • 1:1 ratio
Chrysler Small Block Crankshaft Pulley 2V - High Flow
Click to expand...


There should be a pulley that will get you 3% over. I’ll find my receipt and post the part numbers.
 
Ok, I found it. They are big block pulleys. You want a BCRL2CR-HF and a BCRL1WP-A. That will get you 3% over.

I’m trying to get enough support to do an over drive pulley system that is serpentine and get the thing 15-18% over. I think I need to be able to buy 2k worth of just the water pump pulley.

I don’t want to be sitting on a bunch of pulleys no one will buy because they still think under driving the water pump is a good thing.

I’m working on it though.
 
Rat Bastid said:
Ok, I found it. They are big block pulleys. You want a BCRL2CR-HF and a BCRL1WP-A. That will get you 3% over.
Click to expand...

Just to clarify, these fit on an LA with the aluminum water pump?
 
Rat Bastid said:
Ok, I found it. They are big block pulleys. You want a BCRL2CR-HF and a BCRL1WP-A. That will get you 3% over.

I’m trying to get enough support to do an over drive pulley system that is serpentine and get the thing 15-18% over. I think I need to be able to buy 2k worth of just the water pump pulley.

I don’t want to be sitting on a bunch of pulleys no one will buy because they still think under driving the water pump is a good thing.

I’m working on it though.
Click to expand...

CVF already sells a serpentine pulley set that overdrives the water pump. I'm not sure what percentage though. I have the measurements written down somewhere.

360-SERPENTINE-ALT-2__87474.1552664897.jpg
 
mopowers said:
CVF already sells a serpentine pulley set that overdrives the water pump. I'm not sure what percentage though. I have the measurements written down somewhere.

View attachment 1715855474
Click to expand...


Damn...I forgot about that. My buddy just bought that for his car and I told him to buy it. I was working with March to try and get the overdrive % up.

I’ll call him tonight and have him measure the pulleys.
 
mopowers said:
CVF already sells a serpentine pulley set that overdrives the water pump. I'm not sure what percentage though. I have the measurements written down somewhere.

View attachment 1715855474
Click to expand...


On this pulley set the water pump pulley is 5.125 and the crank pulley is 6.25 so that is about 18% overdriven.

NOTE***** The measurements were taken by my friend so it may not be the exact diameters but he is within a 1/16 or so. I just want to be clear I didn’t measure them to verify the sizing but he is pretty good with a tape. So he is very close. And it sounds about right.
 
Rat Bastid said:
On this pulley set the water pump pulley is 5.125 and the crank pulley is 6.25 so that is about 18% overdriven.

NOTE***** The measurements were taken by my friend so it may not be the exact diameters but he is within a 1/16 or so. I just want to be clear I didn’t measure them to verify the sizing but he is pretty good with a tape. So he is very close. And it sounds about right.
Click to expand...

Thanks! Do you know if they sell the w/p and crank pulleys separately without all the alt pulley and bracketry?
 
You must log in or register to reply here.
-

Back
Top