Changing Crank Pulley Question
Thread Starter
Burning Brakes
Joined: May 2014
Posts: 884
Likes: 128
From: Rhine Georgia
Changing Crank Pulley Question
Stock 79 AC, PS 3 belt system in front of a crate 383. My belts are not 100% aligned (AC is slightly off and PS is way out) and my Alt belt needs replacing. I'm thinking of installing some underdrive pulleys since I'm working in that area. I'm running electric fans so I've got room to work. Is switching the crank pulley a simple swap? I'm not expecting any HP gains. I just want to freshen/smooth things up. My belts have always wobbled more than I like and been a bit noisy.
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
The crankshaft pulleys are just bolted on so they will come off easily. What concerns me is your wanting to put underdrive pulleys on it because that will slow all of your A/C compressor, water pump, and alternator down.
Thread Starter
Burning Brakes
Joined: May 2014
Posts: 884
Likes: 128
From: Rhine Georgia
What concerns me is your wanting to put underdrive pulleys on it because that will slow all of your A/C compressor, water pump, and alternator down.
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
Ecklers offers a pulley kit that increases the wp and alt pullys diameter to compensate. So just the AC and PS are slowed. I'm still not sold on the underdrive. But I do want to update my old factor pulleys even though they may be fine. I'm hoping new tight belts and shimming up the alignment will be a improvement.
If you increase the water pump and alternator pulley diameters you will slow them down even more so that's the last thing you want to do. By installing an underdrive crankshaft pulley you will create all kinds of problems. The underdrive crankshaft pulleys are made to reduce horsepower loss for serious drag racers who need every horsepower they can get.
I suggest correcting your alignment problem and leave it at that.
Thread Starter
Burning Brakes
Joined: May 2014
Posts: 884
Likes: 128
From: Rhine Georgia
If you increase the water pump and alternator pulley diameters you will slow them down even more so that's the last thing you want to do.
Copied from Ecklers site because my link is not working.
Features an undersized crankshaft pulley that turns the belt driven accessories 25% slower, preventing parasitic horsepower losses to the air conditioner and steering pump. The kit's oversized alternator and water pump pulley give a 25% and 17% increase, respectively, over factory pulley to keep those two accessories turning at their proper speeds. All kits come with 3-grove crank pulley.
Last edited by Bloodzone; Nov 21, 2015 at 05:32 PM.
