Did something that made a big difference in cooling...

[Ghoste]

I put on a fixed pitch fan.  I had a Chrysler flex blade fan on it before and I went from that 7 blade one to a 5 blade one but fixed pitch.  BIG difference!  I made the change a few days ago and the car has consistently run 10 to 15 degrees cooler.  I'll take it. 

[68X426]

I got to ask the dumb question. What's a fixed pitch fan? Who's the manufacturer? 

[Ghoste]

Chrysler manufactured both of the fans in this case.  The fixed pitch just means that it is a rigid blade, not one with a flexible edge.

[firefighter3931]

Thats good news ! 

What rad are you running ; 22in or 26in ?

Are you using a shroud ?



Ron

[Ghoste]

It's a 22 inch with 67-68 style metal shroud.  I finally got the shroud on this spring and it helped, but not as much as I thought it would.  At the same time the shroud went on, I put the correct rad mount brackets on which moved the rad closer to the cradle and prevented air bleeding off the top and bottom of it.  It's a fairly new recore and a high efficiency one but it still tended to run to the high side of the temperature range.  I was going to put the viscous drive and the 5 blade on at the same time I had the rad out to replace the brackets (the old brackets didn't permit enough room to run the viscous drive) but decided against it because the trip to Columbus was coming up and naturally a 7 blade fan on a fixed hub is going to move more air than a 5 blade on a coupling that can slip, right?  Wrong.  I'm not sure my results are conclusive because as I said, the flex fan is a Chrysler unit but it is old (70's?) so I can't say that new flex blades are stiffer than ones that have been getting their shape changed for a lot of life cycles.  My guess is yes and that they were staying flat pretty much throughout the rpm range.
So anyone having cooling problems, you may also want to look at the fan (and if you have one of those aftermarket flex fans with the silver blades and blue hub that every smallblock Chevy in the world runs, you need to lose it anyway but that is a whole different issue).

[Road Dog]

I put on a fixed pitch fan.  I had a Chrysler flex blade fan on it before and I went from that 7 blade one to a 5 blade one but fixed pitch.  BIG difference!  I made the change a few days ago and the car has consistently run 10 to 15 degrees cooler.  I'll take it. 

I did this years ago only because one of the flex fan blades broke. The Viscous type would not fit on my car. So I went with a 5 blade fixed type. I did notice it kept the car cooler in traffic.

[firefighter3931]

Thanks for the info Shawn.  Mine is still running hot (200*) at idle but cools down to 170* out on the hwy. Airflow at idle isn't sufficient with a 3000cfm puller fan it seems. I bet it would cool better with a shroud and mechanical fan. These downflow aluminum rads don't cool as well as i would have expected. 

The next rad (coming soon  ) is gonna be a crossflow with shrouded twin puller fans. 


Ron

[68X426]

Thanks for the info Ghoste.

[bull]

I've got a couple of basic (some might say dumb) questions. What temperature range should a big block Mopar be running at? What temp should a BB Mopar thermostat be set at (or, at what temp should the circulation start)?

[elacruze]

I've got a couple of basic (some might say dumb) questions. What temperature range should a big block Mopar be running at? What temp should a BB Mopar thermostat be set at (or, at what temp should the circulation start)?

A couple basics for any engine;

The oil must heat to above 212* somewhere in the engine, just to boil out any condensed water.
Combustion chamber heat makes power. More heat, more power. Of course, there are many factors that limit this heat level.

I run a 190* T-stat in mine, and no matter whether in stop-and-go traffic or uh...'running around' it just lays around between 190* and 200*. I have the hemi radiator, fan and clutch, and shroud.

[maxwellwedge]

I have had a lot of luck with a 180 t/stat......but then again I live in Igloo country. 7 months of winter, 5 months of bad skiing! 

[Ghoste]

Come three hours west and you can have 6 months of wet snow and 6 months of hot and humid.

[ACUDANUT]

pic's of the new fan ?

[Ghoste]

It's just that goofy looking Mopar Performance one.

[ACUDANUT]

 I still believe in the Viscus fan clutch style. (easlier on the water pump bearings) And does not work as hard.=more HP