ENGINE COOLING - Overdriven H2O pump pulley + high flow pump OK?

[68 Sport Satellite]

On my B-body I've got some pulley changes in the works due to working on an aftermarket A/C installation, but this weekend I'm also trying a new higher flowing Flowkooler water pump.

I've noticed that stock replacement water pump pulleys for cars with A/C are smaller than the crank pulley and stock replacement water pump pulleys for cars without A/C are usually a 1:1 diameter between the water pump pulley and crank pulley diameters (and some are even a little bigger diameter).

At the same time, OEM water pump impeller design seemed to target slower moving coolant (less vanes) for A/C cars. I didn't realize until just now that it may be due to countering some of the opposite effect from the smaller water pump used on A/C cars.

So for a stock configuration we're seeing 2 things:
Non-A/C car: larger water pump pulley (not overdriven compared to crank pulley diameter) + faster moving coolant (higher pump fin count)
A/C car: smaller water pump pulley (overdriven, faster moving pulley) + slower moving coolant (lower pump fin count)

On my originally non-A/C car I currently run a stock 1:1 pulley ratio (larger water pump pulley) + lower fin count water pump. This does not match either of the above stock configurations. Right now the car runs between 185-195F in normal stop and go traffic or speed (Excellent), but has occasionally crept up to 215-230F after extended idling (20 min) and immediately cools back down after 30 sec of 20mph or more. This weekend Since I'm not able to find any smaller single groove water pump pulleys of the correct depth (unless I buy this one and shim it from the back - not sure if that's ok to do....)
I'm installing a high flow high fin count Flowkooler water pump to get more coolant moving at idle.

Anyone using this smaller single groove pulley? Can I adapt it to my non-A/C setup for the time being with shims to align with the crank and alternator?
Mopar Plymouth Dodge Fan pulley 340 383 440 1 1/4 X 5 7/8 Cuda Challenger OEM E | eBay

So for my future A/C plans that I've started -
I've got an overdriven water pump pulley (smaller water pump pulley, larger crank pulley), so that's good. Would it be ok to leave the new faster flowing Flow Kooler water pump installed with the smaller diameter water pump? Or when I swap the pulleys during the A/C install (still a few months out), should I re-install the lower fin count lower volume water pump? I've read some have cured idle heat issues, only to create a new issue where the higher pressure from the higher flow pump creates an overheating issue at faster engine speeds (3000 RPM highway).

Has anyone run a smaller water pump pulley along with a high flow water pump like Flowkooler and not had any overheating issues at idle or any speed?

 

[RJRENTON]

On my B-body I've got some pulley changes in the works due to working on an aftermarket A/C installation, but this weekend I'm also trying a new higher flowing Flowkooler water pump.

I've noticed that stock replacement water pump pulleys for cars with A/C are smaller than the crank pulley and stock replacement water pump pulleys for cars without A/C are usually a 1:1 diameter between the water pump pulley and crank pulley diameters (and some are even a little bigger diameter).

At the same time, OEM water pump impeller design seemed to target slower moving coolant (less vanes) for A/C cars. I didn't realize until just now that it may be due to countering some of the opposite effect from the smaller water pump used on A/C cars.

So for a stock configuration we're seeing 2 things:
Non-A/C car: larger water pump pulley (not overdriven compared to crank pulley diameter) + faster moving coolant (higher pump fin count)
A/C car: smaller water pump pulley (overdriven, faster moving pulley) + slower moving coolant (lower pump fin count)

On my originally non-A/C car I currently run a stock 1:1 pulley ratio (larger water pump pulley) + lower fin count water pump. This does not match either of the above stock configurations. Right now the car runs between 185-195F in normal stop and go traffic or speed (Excellent), but has occasionally crept up to 215-230F after extended idling (20 min) and immediately cools back down after 30 sec of 20mph or more. This weekend Since I'm not able to find any smaller single groove water pump pulleys of the correct depth (unless I buy this one and shim it from the back - not sure if that's ok to do....)
I'm installing a high flow high fin count Flowkooler water pump to get more coolant moving at idle.

Anyone using this smaller single groove pulley? Can I adapt it to my non-A/C setup for the time being with shims to align with the crank and alternator?
Mopar Plymouth Dodge Fan pulley 340 383 440 1 1/4 X 5 7/8 Cuda Challenger OEM E | eBay

So for my future A/C plans that I've started -
I've got an overdriven water pump pulley (smaller water pump pulley, larger crank pulley), so that's good. Would it be ok to leave the new faster flowing Flow Kooler water pump installed with the smaller diameter water pump? Or when I swap the pulleys during the A/C install (still a few months out), should I re-install the lower fin count lower volume water pump? I've read some have cured idle heat issues, only to create a new issue where the higher pressure from the higher flow pump creates an overheating issue at faster engine speeds (3000 RPM highway).

Has anyone run a smaller water pump pulley along with a high flow water pump like Flowkooler and not had any overheating issues at idle or any speed?

On my RS23V0A****** GTX, I use the Flowkooler pump with the # 2946716 Hemi water pump drive sheave, in conjunction with the # 2806070 fan clutch and the # 2863226 18-1/2" diameter Hemi aluminum 7 blade fan. The combination works very well. The result is the coolant is moving FASTER thru the block, heads and radiator promoting more efficient heat transfer characteristics by having more gallons/minute and higher velocity, in terms of ft/seconds flow rate. As a side bar, I've just purchased a new Glen-RAY # 2998956 max cooling radiator assembly to replace the origional # 2998956 radiator due to tube to tube sheet leaks. I'll have Glen-RAY rebuild the old radiator over the coming winter, for a spare. This is what works for me. BTW, you never stated what engine you are using as there is a distinct difference, between the LA and B/RB water pump flow rate in terms of number of pump "fins" or impeller vanes, their diameter and design point opersting RPMs. Its not strictly a 1:1 relationship. Just my opinion of course.
BOB RENTON

 

[Kern Dog]

I am by no means an expert but I do make notes on what I have done. I've documented what has worked and what sucks.
One disclaimer....sometimes I get lucky and stumble along, not knowing how close I was to a failure.
Examples: A tire that had cords showing is noticed during an oil change. A loose caliper bolt that is noticed during a tire rotation. A battery holddown that was left loose is noticed when checking the radiator coolant level.
In regards to the cooling system, I too have a Flowkooler pump but with factory spec early 1970s pulleys. I have a "Speedcooling" 2 row aluminum radiator, a factory shroud, a 7 blade fan and clutch. My car runs the same temperature once it is warmed up.....low speed cruising, freeway, 110 degrees or 50. Who knows why.....maybe I am charmed?

 

[diesel_lv]

Here's what Chrysler did for pulley ratios. That said, I use the recommended ratio, but a Flowkooler w/p. No cavitation issues.

 

[68 Sport Satellite]

Here's what Chrysler did for pulley ratios. That said, I use the recommended ratio, but a Flowkooler w/p. No cavitation issues.View attachment 1313918

so what pulley diameter corresponds to your recommended ratio?

I'm not going for a stock restoration and not necessarily paying attention to factory configurations, although some of my parts are factory size. I have a cooling system that works well, but when I add A/C, I want it to work as well or better.

Sounds like I may be fine with the higher flowing flowkooler pump in conjunction with the smaller 5" and change water pump pulley. If I have any problems I can always swap the 6 fin pump I got from Mancini back in.

My car is a 1968 Sport Satellite. My motor is a low deck 1972 400 block B-motor built into a mild 451. I expanded my rad opening and dropped a 26" rad with shroud in (Griffin 2 row, 1-1/4" tube diameter), 180F high flow t-stat, 7 blade mechanical fan.

Thanks for the feedback guys!

 

[Archie Duiker]

I am by no means an expert but I do make notes on what I have done. I've documented what has worked and what sucks.
One disclaimer....sometimes I get lucky and stumble along, not knowing how close I was to a failure.
Examples: A tire that had cords showing is noticed during an oil change. A loose caliper bolt that is noticed during a tire rotation. A battery holddown that was left loose is noticed when checking the radiator coolant level.
In regards to the cooling system, I too have a Flowkooler pump but with factory spec early 1970s pulleys. I have a "Speedcooling" 2 row aluminum radiator, a factory shroud, a 7 blade fan and clutch. My car runs the same temperature once it is warmed up.....low speed cruising, freeway, 110 degrees or 50. Who knows why.....maybe I am charmed?

I would guess your coolant temperature gauge is not reading correctly. 110F (50C) is only luke warm, and will result in poor combustion. Should be around 190F - 200F.

 

[68 Sport Satellite]

I would guess your coolant temperature gauge is not reading correctly. 110F (50C) is only luke warm, and will result in poor combustion. Should be around 190F - 200F.

He doesn't mean engine temp, he means outside temp.

 

[Kern Dog]

You are confused.
I meant weather temperature. Who drives with their engine temperature at 50 degrees?

 

[Don Frelier]

You bet he's confused 110 F is 43.333 degrees C.
I thought everybody in Cananda knew that.

I do drive with my engine at 50F degrees on most winter mornings but only for a millisecond as it heads towards 190F.