Posted by Don in Missouri [12.206.185.66] on Wednesday, April 15, 2015 at 00:36:40 :
In Reply to: Paul will this 4bt crank pulley fit the 6bt posted by edcr [201.202.24.222] on Tuesday, April 14, 2015 at 11:27:20 :
The crank pulleys will interchange between 4bt and 6bt. Most of the 4bts come with just a pulley and no harmonic balancer. There is a marine balancer that will bolt to the plain pulley with a spacer. You can put a 12V harmonic balancer on a 4bt. It is not engineered specifically for the harmonics of a 4 cylinder, but I believe what I've been told that no amount of angular momentum added to a 4bt is a bad thing. None of these will change the position of the belt.
The 24-valve motors have a larger diameter crank pulley, so if you wanted to spin your accessories faster, you could do that. However, the 24-valve pulley sits back farther (just a few mm), so you either have to make a spacer to put it in the same position as the 12v pulley, or you must shave the oil pan and timing cover, so the 24-v pulley does not hit your 12-v motor.
In any case, you really can't move the belt closer to the motor. You can get fan pulleys with different depths or diameters. The key to getting a fan pulley closer to the motor, is getting a fan hub that does not projects as far. I don't know that I have seen a low-profile(flat to the motor) fan hub. I have seen a couple different fan hubs that position the pulley at different heights. The common 4bt fan hub is the lowest mount. I want to say the Dodge 6bt is higher, but it might be the same as the 4bt. The Ford medium duty 6bt fan hub mounts higher-so much so, that you'd be unlikely to fit a fan under the hood of most light duty swaps.
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