I have replaced the crank pulley on my 390 because I added power steering and plan to add AC at a later time. My problem is the new pulley is quite a bit smaller, how will this affect the water pump and alternator?

 

It will drive everything slower.... if this creates a problem, you'll need to install smaller pulleys on everything else.

 

Ugh why don't the vendors put this information in their discerption!?

 

.....mo money.....

 

https://www.google.com/amp/www.hotro...cles/pull/amp/

 

Wait a minute now, hold the bus. So if i reduce the size of the crank pulley the alternator and water pump spin faster ?

 

Look on the Ford pulley for its ID engineering number, post what it is.

1968/72 F100/350 360/390 single sheave outer crankshaft pulley is 6 25/32" O.D. and its ID engineering number: C8AE-6A312-B

1968/72 F100/350 360/390 double sheave outer crankshaft pulley is 6 21/32" large pulley; 6.00" small pulley and its ID engineering number: C8AE-6312-C

There's also a triple sheave outer pulley for P/S & A/C

 

I'll have to get the exact numbers tonight after I get home, but looking at the photo above you hit the measurements exactly

 

I found this string on an Ford Mustang site

Explain how a smaller crank pulley makes more HP? - Ford Mustang Forums : Corral.net Mustang Forum

 

I like to have my crank pulley at least as big as my water pump pulley it you plan to idle through town. At high way speed it won't matter much what your crank pulley size is. If you're going to drag race and spin 6000 rpms then get an electric pump and fans to minimize power loss. Otherwise, get a bigger crank pulley.

I think the string you found on the mustang site has a little correct but is mostly mixed up. Decreasing the crank pulley size will decrease the accessory speed. Also, the sizes don't make sense. A 40" diameter pulley is bigger than your tires. Even if they meant 40" circumference, that would still be a whopper big pulley.

 

Here it is Number

 

C8AZ-6A312-E .. Outer Crankshaft Pulley-Uses 3/8" wide belt / Obsolete

1968/72 F100/350 360/390 / 1968 Galaxie/LTD 428 / 1968/69 Galaxie/LTD/Fairlane/Torino/Mustang/Cougar 390.

 

Well I'm keeping my fingers crossed, I found an Bump owner with a spare three groove that he is selling me. I only hope its the correct size, the last one I bought online was for a 302

 

C8AZ-6A312-B .. Triple Sheave Outer Crankshaft Pulley (bolts to the harmonic balancer) / Marked: C8AE-6312-B / Obsolete

(2) 7 5/32" inner pulley diameter / 7 13/16" outer pulley diameter / 3/8" belts on inner pulleys / 1/2" belt on outer pulley.

1968/71 F100/350 360/390 // 1968 Galaxie/LTD 390/428.

KLIMESH MOTOR SALES in Calmar IA has 1 = 563-562-3241.

CARPENTER NOS OBSOLETE PARTS in Concord NC has 1 = 800-476-9653.

GREEN SALES CO. in Cincinnati OH has 10 = 800-543-4959.