Need correct crank pulley!!!! Any ideas?

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ariffle

Fish Shouldn't Rust
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I am looking for the correct size crank pulley for my pre. 74 318.
Apparently the one I have currently is the VERY small diam. one and could be the reason why my engine can't stay cool.
I have noticed that EVERY 318 I have looked at that was a strip car only, has this same small crank pulley and all the street drivers have the larger diam. crank pulley.
So, that's my dilema and need to locate the correct pulley. I do like having a double belt setup that you see in the pictures. I'm sure it isn't how it was originally intended by Ma Mopar, but that's the setup that I had when I pulled the car out of the field 8-9 years ago and restored it.
I have had overheating issues from the start. I an seriously thinking that this pulley is the key.
Any thoughts from those that know their stuff, PLEASE chime in. Thanks!

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That is the smallest crank pulley diameter I have ever seen.

Can you shine a light on it & get a better photo?
 
You need a std double crank pulley? 7.5 diameter? I cut a 4 pulley in half.....Yours free, just get it there.
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Interesting.

Dual pulley alternators are normally for AC applications.

A normal dual lower lower pulley has a larger diameter on the outer one for power steering.

So that would be difficult if you want to keep matched belts.
 
Your best bet is to find a smaller water pump pulley along with a larger crank pulley so you can drive the water pump faster than the crank.

I'm using a 5 3/4" WP & a 7 1/4" crank. Your 2 pulley diameters when added together cannot exceed 13"....
 
Your best bet is to find a smaller water pump pulley along with a larger crank pulley so you can drive the water pump faster than the crank.

I'm using a 5 3/4" WP & a 7 1/4" crank. Your 2 pulley diameters when added together cannot exceed 13"....
Very good information, I didn't know about the max. diameters added up. thank you!
 
Very good information, I didn't know about the max. diameters added up. thank you!

I'm sure changing your pulleys will help your cooling issues tremendously. Read that link I posted above when you have time. Lots of good info from members :)
 
I thought it was my eyes, but with the later pix, that is not right at all...for street use. It looks like someone scabbed in some sort of idler pulley onto this engine. The tiny diameter at the strip is just to make the pump and alternator turn much more slowly and not pull as much HP from the engine.

The normal crank pulleys are dished and bolt to the face of the damper with 6 bolts. The center bolt does not hold the crank pulley on in the stock setup.

So you will need a proper length/diameter/thread damper bolt; that needs to be torqued to 135 ft lbs to make the damper do its job. That bolt has a very thick steel washer under the head to clamp that high load properly. Then that larger crank pulley and the 6 bolts to fit the holes in the damper.

You don't need double belts at all for standard use without PS and A/C.
 
The typical lower crank pulley for manual steering has one groove & about a 6 1/2" diameter.

This aftermarket cast iron pulley was part of an AC system added to a manual steering car.

Same outer pulley diameter.

So if you really want a dual belt system, this may be one way?

It does have the offset bolt holes for the older crank dampers, I just pulled it off a '70 last week.

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I'm sure changing your pulleys will help your cooling issues tremendously. Read that link I posted above when you have time. Lots of good info from members :)
Thank you for the help. Now, all I need is to find some pulleys that size and a couple new belts. I'll be so happy when I can drive this awesome car without watching the temp. guage non-stop. Thanks again!
 
March makes a performance ratio two groove pulley for the older style water pump. . It is slightly smaller than stock. Here’s a picture. Actually I don’t think that will work because the second groove is for power steering so the second groove is “inside” or towards the motor. You want the second groove towards the radiator. You could just go single belt and be done.

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All my rally cars use 1 v-belt to run water pump and alternator. Smaller water pumps, but the alternators put out 80-130 amps to run up to 6 rally lights at night, plus the normal electrical loads. Standard stock pulleys, and 6500 RPM on 2 engines and 8000 RPM on the other. Never threw a belt.

BTW, OP, throw those inside-cogged v-belts into the trash right now. They are notorious for slipping but not making a squeal, so they can be doing very little to turn the alternator and water pump, and you will never hear the slippage and never know it. I have been bitten twice by them in 2 completely different applications. I'd recommend NAPA Premium belts.
 
your water pump-- solid impeller or with a plate behind the stamped fins
prevents cavitation and water circulating around the stamped fins
 
your water pump-- solid impeller or with a plate behind the stamped fins
prevents cavitation and water circulating around the stamped fins
I don't remember. It is the O.EM. style water pump, so whatever those are.
Anyways, I'm fairly curtain that my heating issue is the cause of incorrect pulleys. I am on the hunt for a water pump pulley that is 5 3/4 Diam. And a crank pulley that is 7 1/4 Diam. I think that will solve my issue.
 
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