Well, I determined a problem that I knew existed was more of an issue than I initially believed. The stock fan from the Cummins has a couple bent blades. Now, they are not bent horribly, but I am not too excited about straightening a fan blade. I did a bunch of research and learned a few things. The first thing I learned was that these fans were known for pitching blades off at speed--not good, but even worse when the stock viscous clutch is replaced with a direct drive clutch that has no "cushion" to speed up. The clutch engages and it is at speed right now. This is not a good mix with a fan known to pitch blades.
The next thing I learned is that this fan is not correct for the fan hub I am using. A few posts back there are pics of the differences in the fan hubs. The main difference is the length of the hubs. The offset one sticks out further than the non-offset one. The fan I have is designed for the longer hub which creates a fitment issue when run on a short hub. This pic illustrates what I was going to do until I realized my problems were more severe than I initially thought:
In the pic it is just barely visible, but the clutch is not threaded completely on to the hub. This is for clearance between the fan and crank pulley. I thought it would be ok because it did not hit and the fan would, in theory, pull away from the engine toward the radiator when engaged. Then I learned how crappy the fan was stock among other things and decided something else needed to be done with it. The stock fan itself is a rather weak fan compared to others I have used in the past which did not thrill me, but what could I do?? The fan is a strange animal. Here are a couple pics to illustrate the strangeness:
Not too strange looking, right?? Well, flip it over it gets stranger:
Add a tape measure and it gets real weird:
Yes, that is about 3/8" of backspacing on that blade. This may be typical of an inline motor, but as a purveyor of V-configuration motors it is real weird to me. Now, to use a stock blade I would have to find one that has LESS than 3/8" on the backside. Hmmm, does not sound like fun. I got no help from Dodge on what fan I could use because there were a bunch of variables. This motor, originally being non-intercooled, got a smaller diameter fan than the intercooled motors. That coupled with the using of the different hub got me nowhere. So, what to do?? I had one of the super-bishin' big block fans (the one that the big seven blade fans from the 70's supersedes to because it pulls so much more air) from the previous motor, but the backspacing on it was tremendous compared to the stock Cummins fan. That's not going to work--or is it?? Hmmm.
Man, that's a lot of backspacing. Probably can't be done so I think I'll give it a shot. Let's see here. May as well try a test fit:
Yup, just as I thought--it hits everything. Oil fill tube, water pump pulley and crank pulley. Not good. Well, what if it could be spaced out a bit. By my measurements it would take a fuzz under one inch. Hmmm, how to make a temporary one inch spacer to test my theory??
A couple pieces of half inch square tubing cribbed should suffice:
Wow, it clears everything nicely. Maybe I am on to something. Now what do I do about making something a bit more permanent than the stacked tubing. I consulted my personal machinist Russ (BadDog). He thought it sounded easy enough and agreed to give it a shot. I went over to his shop with a round slug of metal that i have had for years, a fan hub, a couple pulleys and one dimension--one inch out from the fan mounting surface. Well, it turns out that my slug was crap. It had terrible cracks in it just under the surface and would not clean up.
A new slug will need to be located.