Undersize water pump pulley for SBC?

[King Herald]

Having messed about forever with this motor getting too hot on real hot days in heavy traffic, I finally bit the bullet and ordered up an aluminum radiator from Summit. And a big electric fan.

It is not until now, when I have the front end all torn down, that I'm looking at my water pump pulley and thinking that if it were a touch smaller I could be moving more water at idle.

Is it normal for crank and water pump pulley to be the exact same size? Mine are. off to my buddys treasure (junkyard) house on Monday to see if he has something a touch smaller that will fit.

Here's an old pic.

 

[smallfoot]

The fan pulleys on a 250 I6 are smaller in diameter but you would have to fab a spacer to line up the grooves. My sbc pulleys are pretty close to the same size on fan and crank...

 

[Bamamav]

Smaller pulley might move the coolant too fast, not letting it stay in radiator long enough to cool down.

 

[King Herald]

Smaller pulley might move the coolant too fast, not letting it stay in radiator long enough to cool down.

That seems to be the trade-off; better cooling at idle and in traffic, but not so good at higher rpm. I'll see if I can find a slightly smaller, see if it makes any difference. Probably a good idea if I make one change at a time, so I'll fit the radiator and see if it cures the problem before doing the pulley.

 

[Tripper]

Didn't work for me & I wound up notching the crossmember!

BoB

 

[King Herald]

Didn't work for me & I wound up notching the crossmember!

BoB

I guess you fitted a bigger crank pulley? Unless I shrink the top one I can't get a bigger crank pulley in there.

 

[donsrods]

I don't think pulley size is your problem. Here is a picture of my sbc with the correct sized pulley set on it, pretty much same as yours:



Does your car cool down when you are going down the road, but heat up when you stop for lights ? If so, that is an air flow problem. What fan did you order ? IMO, one of the best is a SPAL electric fan, they move a ton of air.

Sbc are generally the easiest engine to keep cool, by design. I couldn't get the one in my modified over 150, maybe 170 at lights.

Make sure your intake gaskets are on the correct direction, some have a hole that gets blocked if you flip them around. Try the bigger radiator with a good fan (again, I love SPAL fans), and try it without a thermostat for a test. I am not running a thermostat in my 331 stroker as it likes it that way the best.

As for spinning the water pump faster, when I first put together the 331 in my 27, I had a set of Zoops pulleys, and the top one was smaller than the crank pulley. I blew two water pumps apart (literally !) because I was spinning them so fast. After I put on the correct pulleys, I never had that issue again, and the smaller pulley did not help cooling when it was on there.

Don

 

[Old Iron]

If your SBC is heating up, you most likely will cure it with the radiator swap.
Like you said, one thing at a time.
I would not use a smaller pulley on the water pump either.
As mentioned by Bama, there's a common misunderstanding on how a radiator works. The coolant has to run through the radiator slow enough for the heat to be removed from the fluid.
Also an aluminum water pump is more efficient than a cast iron one.

 

[Tripper]

IMO, one of the best is a SPAL electric fan, they move a ton of air.

I agree... I use a bigger radiator & this puller Spal fan on nearly all my cars! Never have any overheating problems even in the hot Tejas summers!

http://www.jegs.com/i/SPAL/063/30101516/10002/-1?CAWELAID=230006180000986453&CAGPSPN=pla&CAAGID=15769068431&CATCI=pla-176568839831&catargetid=230006180003463698&cadevice=c&gclid=CPq62sGmucwCFQyNaQodcAIE3w

BoB

 

[donsrods]

I had always run the typical Autozone electric fans, and they lasted just about a year each before they would crap out. Then I bought a SPAL, and the first time I hooked it up to a battery, it almost blew out of my hands ! That thing was powerful and moved a ton of air.

They also last and last. The one on my 27 is 8 years old and still runs like new, same with my Sons T bucket, and Dan's rpu. Had one on my 23 too, and it was 5 years old when I sold the car and I bet it is still running today.

Don

 

[I-R-POPS]

I had always run the typical Autozone electric fans, and they lasted just about a year each before they would crap out. Then I bought a SPAL, and the first time I hooked it up to a battery, it almost blew out of my hands ! That thing was powerful and moved a ton of air.

They also last and last. The one on my 27 is 8 years old and still runs like new, same with my Sons T bucket, and Dan's rpu. Had one on my 23 too, and it was 5 years old when I sold the car and I bet it is still running today.

Don

Hey Don,
How loud are they? That's my biggest gripe with an electric fan. But I keep thinking I'll need one on my old truck when I build the motor.

 

[soltz]

Hey Don,
How loud are they? That's my biggest gripe with an electric fan. But I keep thinking I'll need one on my old truck when I build the motor.

With the right exhaust you'll never hear it

I ran a double on my 56, blown SBF, couldn't hear it over the blower wine, just ask my wife.

 

[donsrods]

Hey Don,
How loud are they? That's my biggest gripe with an electric fan. But I keep thinking I'll need one on my old truck when I build the motor.

Well, yeah, you can hear it running, but it isn't all that loud to me. I'm willing to trade a little noise for not having to worry about overheating, though.

Like Soltz said, a nice loud exhaust tends to cover it up.

Don

 

[I-R-POPS]

With the right exhaust you'll never hear it

I ran a double on my 56, blown SBF, couldn't hear it over the blower wine, just ask my wife.

You better be careful, she will slap you upside the head.

 

[I-R-POPS]

Well, yeah, you can hear it running, but it isn't all that loud to me. I'm willing to trade a little noise for not having to worry about overheating, though.

Like Soltz said, a nice loud exhaust tends to cover it up.

Don

Thanks. I may have to try one if I have any issues.

 

[Tripper]

Hey Don,
How loud are they? That's my biggest gripe with an electric fan. But I keep thinking I'll need one on my old truck when I build the motor.

The ones I use aren't all that quiet but in our summers they're definitely worth it! Mine are on a Derale adjustable controller & doesn't run all the time. Sometimes it'll come on when I have to wait in a line for fast food etc.... I've had several people at the window ask if I was running a blower? I always say 'kind of'... but guess a sucker is more accurate... haha!!! [ddd[ddd[ddd

BoB

 

[King Herald]

Well, what a strange world, I do indeed have a 16" 2000cfm Spal fan I ordered last week that is going on. $160 worth of fan, and a Hayden adjustable controller for it too.

I found a nice chrome WP pulley in my buddies pile, that is just 1" smaller than original. That will make about 10% increase in water flow at lower rpm, which is where I need it, as 90% of my driving is done under 1000rpm unfortunately.

Odd that a water pump would explode, when a 16" heavy duty old beater of a mechanical cooling fan can run at 6000rpm. I'd guess my after-market water pump will be good for high revs, and I'll never go past 6000rpm, so I think it'll be okay for me.

There is no cooling problem once I get a bit of speed up, so water going too fast shouldn't be an issue....... If it runs cool as I want, I might just put the bigger pulley back on. No point running anything faster than it needs to go.

 

[Tripper]

$160 worth of fan, and a Hayden adjustable controller for it too.

I prefer adjustable controllers... not all engine/cooling systems are the same & being able to change the settings at will is great. The setting for the new motor in my Nova is a lot different (same radiator) than the old motor.

Let us know how it goes... we need photos too!

BoB

 

[soltz]

You better be careful, she will slap you upside the head.

Already been done

 

[King Herald]

Funny, but it don't look any different in size here. But with a rule it is an inch smaller. Fitted right on too.

It has dual grooves, so when I fit AC......

I also fitted a new crank dampener as the old one had been drilled and pinned.... [S

Crowded shop, need to sort my junk out.

New rad in frame, under construction.

Big enough fan? it is mounted low as the water pump snout gets real close if it is central. Won't make any different to operation though. Will it?