Shameful Post...Fan Belt Install Issues

[911SauCy]

Simply put, I'm having an incredibly difficult time installing the belt onto my motor.

I've done this numerous times, but on my other '78 3.0, this motor is an '83 930/10. I swapped this pulley from my other motor to this...

I've got the 6 total shims, tried 3/3, tried 4/2, and finally 5/1. With the 5/1 I installed the nut, began to snug to move the belt better into place. Within a couple threads the belt was beyond the 10-15mm diffelction spec and over taught...nevermind the outer pulley not being engaged into the tooling of the fan.

My guy tells me that despite the new belt being the proper one, maybe it's too short for use with this pulley...?

Belt is a Continental 10x710

[Flat6pac]

The fan and pulley half are pre 76 requiring a smaller crank pulley to accommodate the 710 belt
The SC runs a faster fan, smaller fan pulley and larger crank pulley.
You want the fan and pulley half with the small holes all the way around.
Bruce

[Flat6pac]

Later fan with small holes

[john walker's workshop]

A 10x735 often works with that setup if a 10x725 doesn't.

[911SauCy]

I was aiming for the belt being the solution, but if I do just change the belt does the different pulley size mean i’llend up with less cooling?

Frankly, I like the pulley I have better than the “correct”one...

Or, should I get the SC correct smaller pulley?

[Trackrash]

Since you changed the outer pulley half you have essentially changed the diameter of the fan pulley. I did the same basic thing on my car. As John stated you will need to use a longer belt. I used a 10 x 740.

Keep in mind that the fan will turn slower AND you have the smaller 225mm fan which was designed to turn faster than the older and newer fans and alternators.

You will indeed need to make sure that your fan cools the motor adequately AND that the alternator is keeping up with your cars demands with your backdated pulley. You could be OK, but hot weather and an AC may make that difficult.

I used an older fan on my motor, the best of both worlds.

[911SauCy]

Then can you define how "small" a small fan is? This fan (with a 901xx..housing) center came off my core (which had been swapped previously when the alternator failed and fan/housing siezed/broke) and fit into the outer housing that you see which is the stock '83 930/10 housing...so an '83 930/10 has a "small" fan also? See the confusion...? Theres all this talk about xyz fan size, but i took one and put in another that theoretically shouldnt have fit and it fits like a glove

Lastly, if i just run the correct pulley I'd be better off cooling (smaller dia/higher rpm etc)?

[Walter_Middie]

Then can you define how "small" a small fan is?

From my notes...and this is inconsistently shown in the various parts books, so don't hold me to it, it may be one model year "off":

1965-74/75.. 110 mm crank pulley..95 mm fan pulley
1976-77... 130 mm crank...83 mm fan ( may be 80?)
1978-79....130 mm crank... 80 mm fan ( or was that 83?)
1980-89.....120 mm crank....83 mm fan ( or was that 80?)

for fan sizes / blades / air flow:
1964-1968….250 mm / 11 blade
1969-74/75....245 mm / 11 blade... 1.3:1 ratio..1390 liters air/sec
1975/76- 77.....245 / 5 blade.......1.82:1 ratio....1265 l/sec
1978-79...........226 / 11 blade ...1.81:1 ratio...1380 l /sec
1980-89.........245 mm / 11 blade...1.67:1 ratio...1500 l/ sec
1989-1998 3.6L 12 blade…..1.6 ratio…..1010 L/sec

80 mm=3.15 in
83 mm=3.27 in
95 mm= 3.74 in
110 mm=4.33 in
130 mm=5.12 in

[911SauCy]

I'm just going to get the proper 83mm pulley for now.

Function over form this time around as I do have a 245mm fan and the '83 motor has the 120mm crank pulley.

With the larger crank and fan pulley, I'm willing to venture a guess that my L/sec figure was below the 1200 figure