mauls

Are the pulleys on the 425 interchangeable with the 455?

Reason for asking is I need new pulleys for my 425 motor and I figured it'd be easier to find pulleys for a 455.

Also if anybody knows where I can find some, that'd be great!

I tried to swap the pulleys from a sb 260 to a 425 and they wont work.

Thanks in advance!

svnt442

Nope. The bolt patterns are different from the older pulleys/harmonic balancers that's why they won't work.

mauls

Thanks for the info

I found a set on Mondello's but I always hear they are over priced. They want $299 for a set of aluminum pulleys, which include water pump, crankshaft and alternator pulley (with cover plate for alternator pulley). It says these pulleys will fit 330-455 engines.

I hope there is another alternative out there, i didn't want to spend this much on pulleys.

joe_padavano

I don't believe that's correct. The CRANK flange bolt pattern is different on the 64-67 motors, but the balancer pattern should be the same. Of course, this is a moot point, because the pulley offset is a function of the accessory brackets and the water pump length. It doesn't matter if the pulleys are off a 425, 455, or 307. What matters is that the grooves are offset the correct distance from the pulley mounting surface.

mauls

Yes the water pump length is the problem that we ran into with trying to use the pulleys form the sb 260

svnt442

Ok. I thought I saw that someone had an issue bolting a pulley in a 330 balancer a while ago due to the bolt pattern being different. I must be developing alzheimer's in my old age.

If the water pump length is the issue you should be able to swap to water pump that matches the length of the 260 pump and the pulleys should line up.

mauls

The water pump on the 260 is trash, I already bought a brand new one for the 425. So I'm guessing I'm going to have to purchase the kit from mondellos

2blu442

Only if you want the aluminum pullys! I'm sure There's several of us here that have extra pullys, it just may take some doing to find out which ones you need. What is the motor going into? Are you using the power steering pump from the car the engine is going into? How many grooves are on that pully? Will it have AC or not? Do you have any pullys already that you need to match up? John

bigoldscruiser

I'm waiting to see your answer to 2blu442. I may have what you need from an old 425.

mauls

The pulleys I need are for a 1966 425ci. I tried to use the pulleys from my 260ci, but the waterpump on the 260 was much longer, and the pulley was deeper. If i use the deep pulley for the 425 it hits the water pump. So I need a factory(shallow pulley) for a waterpump on a 425, and possibly a power steering pump, but i'm sure the power steering pump may be the same.

If anybody has all three pulley's i'd be glad to purchase all three from them so I know that they will all work out.

Thanks

mauls

Have another compatibility issue

Apparently the power steering pump bracket on the 260 is too long for the 425, and it sticks out to far. Are there shorter power steering pump brackets out there? For a 1966 425

joe_padavano

The power steering pump bracket on a 260 is no different than the PS pump bracket on any 1968-1990 Olds V8. Your problem is that the 64-67 cars used a completely different bracket that mounted the pump high on the driver's side. How exactly is it too long? Is this a pulley alignment issue or a hitting the frame issue?

2blu442

Are you wanting to match the original style for that year or does that matter to you? As Joe said, the early years used a power steering pump mounted up high on the drivers side of the engine. The newer ones have it mounted lower and near the power steering box. Let us know if its important to you to keep the early style or not, and if you have an AC compressor. Then measure the length of the water pump, that's from where it mounts to the engine to where it fits behind the pully. I'm sure there's several guys here that have extra pullys, but we need a little more information to help you. John

MrRocket

I need to check but I might have what you need. I took a 425 Toro. motor and put it in my 74 Cutlass and used the brackets from a 74 Cutlass. I think I still have all the brackets from the 425 somewhere. When it stops raining I will go check my parts car and see if they're in the box in the trunk. If you find what you need elsewhere buy it. I don't know for sure if I have it, but I should. Let me know if you're interested. I'd save you some money from Mondello's price.

MrRocket

Also, I noticed you are close enough to make a road trip and see for yourself if they would work and save shipping costs. I'm just down the road from you.