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I’m replacing the oem engine pulleys on my 73 big block.
The power steering and the air pump have been deleted, there is no idler pulley, but I will be still be running ac.
The original crank pulley was two groove and the water pump was a three groove.
Do I still need a three groove pulley on the water pump or can I run just a two groove pulley?
Just for clarification: I’ll be running the water pump, alternator, ac and of course the crank pulleys.
Thanks
Last edited by OldCarBum; Jun 14, 2023 at 02:08 PM.
I think you should go with the setup below. The innermost crank to w/p should be by itself and you may want to reconsider the idler as it makes installation much easier. Then the crank, w/p, and alternator on the middle groove of the top pulley with the A/C driven by its own belt off the forward most w/p groove.
The idler isn't absolutely necessary. My 427 doesn't have one, my 454 does. Without is a real struggle to get the belt on but with is just mildly taxing. I'm sure there are other benefits to having one but I don't know the full reasoning as to why some had them and others didn't.
The AC puts a big load on the WP pulley/belt. And that is attached to the crank pulley by another belt. If you can get a belt that is just short enough to be tight enough, between crank and WP, for it not to slip, then you could make it work. But it would be a challenge getting the WP pulley on with the tight belt already attached. I'll going with the idler pulley on mine to make make belt adjustments easier.
Ok, I’ll ask this question.
If you have one belt going around the wp, crank and alternator, do you really need the belt going around just the wp and crank?
When I pulled my engine down and apart, the wp and crank belt wasn’t installed and I drove it that way for close to seven years with no issue.
The empty pulley was there but no belt.
I’ve read older threads discussing how to install the wp and crank belt by removing the wp pulley and reinstalling it with the belt on both pulleys.
These were on engines designed without the idler pulley assembly.
Listen to what your engine has to say...."I have too much power for you to not install the crank to water pump belt, I don't want to rely on the alternator belt" !
Ok, I’ll ask this question.
If you have one belt going around the wp, crank and alternator, do you really need the belt going around just the wp and crank?
When I pulled my engine down and apart, the wp and crank belt wasn’t installed and I drove it that way for close to seven years with no issue.
The empty pulley was there but no belt.
I’ve read older threads discussing how to install the wp and crank belt by removing the wp pulley and reinstalling it with the belt on both pulleys.
These were on engines designed without the idler pulley assembly.
I suggested in a thread within the last year or so that the multiple belts connecting the crank and water pump was a back-up sort of design. This was roundly panned by a more knowledgeable engine forum member. The reply was along the lines of the double belting was necessary due to the engine torque. I'll see if I can find the thread and link it later.
As I mentioned up thread, my 427 has no idler. I replaced the original belt last year when I put in a new timing set. I found it much easier to install the inner belt with the pump pulley fully on the water pump shaft with the studs installed while stretching it on the crank pulley. The lower crank pulley is much easier to get aligned with the bolts while stretching. I had issues with getting the upper pulley installed on the w/p since there's no way to hold the shaft from rotating.
Engine Pulleys
