318 pulley mistake, need the correct size.

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Ant

Ant

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Finally getting the pulleys on the motor and well... the pulleys for the crank and water pump hit each other and both cannot be bolted on together. I bought these pulleys a good while ago and they are supposed to be for a 318, 340, or 360 with A/C. I have been trying to keep stuff like this correct enough for the 73 model year for my Dart /6 to 318 conversion and going with factory A/C and P/S and whatever is similar, so now I need to find out what the actual pully sizes should be.

What I have:
Crank diameter 7 1/4 - 7 3/8"(3 groove) 3 1/8" maybe deep.
Water pump diameter, 6.5"(single groove) 2 1/8" deep.
Belt alignment looks like it may be ok by eye, but I really don't know for sure.

I don't know if one or both are wrong, any help with the measurements is appreciated.
 
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On my '85 318, four groove crank is seven inches for the forward two grooves (rear two are bigger by about 3/8-1/2 inch). The two groove water pump pulley is six inches.
 
With no information on your car it’s pretty hard to guess. It if I have too I’d say both are wrong by your measurements. R u putting this 318 into a ford, Chevy or Tesla? Pics and information go a long ways. Kim
 
oldkimmer said:
With no information on your car it’s pretty hard to guess. R u putting this 318 into a ford, Chevy or Tesla? Pics and information go a long ways. Kim
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Oops! I forgot to put the car info.
73 Dart, doing a /6 to 318 swap with a factory A/C setup. I still need to find the correct hoses on my parts hunt or get them made, but the concern now is the two pulleys I'm having issues with.
I don't have pics of the pulleys, but the crank is a 3 groove and the water pump is a single, just one or both may be the incorrect size.

I'll update my first post.
 
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Ant said:
the crank is a 3 groove and the water pump is a single
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3-groove crank would be for alternator, A/C, and P/S. Single would be for alternator. You need two grooves for the A/C IIRC. I might have one off a 78 360, will look and see what I can find. It came with a 3-groove crank pulley.
 
Uncle Bob said:
3-groove crank would be for alternator, A/C, and P/S. Single would be for alternator. You need two grooves for the A/C IIRC. I might have one off a 78 360, will look and see what I can find. It came with a 3-groove crank pulley.
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I found one, it's 6" diameter and about 2-3/8" deep. Has the number 3698805 stamped into it.
 
Uncle Bob said:
3-groove crank would be for alternator, A/C, and P/S. Single would be for alternator. You need two grooves for the A/C IIRC. I might have one off a 78 360, will look and see what I can find. It came with a 3-groove crank pulley.
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I have power steering.
I will take pictures of my pulleys later.
 
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If you think you can use it, PM me. It's yours for the cost of shipping.
 
I got some pictures

Water pump pully is 2 1/8" deep.
Crank pulley is 3 1/8" deep.
20240708_133601.jpg
20240708_133621.jpg

Here are some numbers from the water pump pulley.
20240708_134220.jpg
20240708_134211.jpg
 
I have seen where I’ve had to hold up on the water pump when installing it to get pulley clearance. Only the odd time though. This happened with pumps from Napa, Aklands-granger and other parts sources. Kim
 
Ant said:
Thank you, but I still need to find the correct water pump pulley size for a factory ac car. I will need to look for used parts, these new ones cost a lot of ca$h.
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Screw all that. Use the biggest crank pulley and the smallest water pump pulley and a high flow pump.

You’ll be able to drive through downtown hell and hit every light and still stay at thermostat opening.
 
I think both the pulleys are for your engine but are mix matched for years and accessories. I believe Uncle Bob has you covered with a water pump pulley that will be compatible with your crank pulley.
 
Newbomb Turk said:
Screw all that. Use the biggest crank pulley and the smallest water pump pulley and a high flow pump.

You’ll be able to drive through downtown hell and hit every light and still stay at thermostat opening.
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Ha ha! And have the radiator fan spin at mach Jesus, lol.
 
MV8 said:
I think both the pulleys are for your engine but are mix matched for years and accessories. I believe Uncle Bob has you covered with a water pump pulley that will be compatible with your crank pulley.
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My crank pulley could be wrong too. That's why I need to find out what is correct for a 73 dart with a 318 with A/C and P/S. I could guess, but I don't want to have a pile of pulleys that don't work for me.
 
You want to make sure the crank pulley is the correct OD. The size of the accessory pulleys ....& the rpms they turn.......are based on crank pulley size.
 
MV8 said:
I think both the pulleys are for your engine but are mix matched for years and accessories. I believe Uncle Bob has you covered with a water pump pulley that will be compatible with your crank pulley.
Click to expand...
Yes that WP pulley has a matching 3-groove crank pulley too so those two don't run into each other on a small block.

The only question is will it place the accessory pulleys at the right place, based on the later car's brackets. The pulleys will work together but it's possible other belts won't line up.
 
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