Team Camaro Tech banner

1 - 19 of 19 Posts

·
Registered
Joined
·
1,740 Posts
Discussion Starter #2
^^anyone?

Having a "discussion" with some other 1st gen owners who feel the 5 blade, because of its assumed wider blades, does a better job than the 7 blade, with assumed thinner aka "less wide" fan. FWIW I have the 5 blade and don't have cooling issues other than once in stopped traffic for at least 20+ minutes on a 100+ degree day my temps did get to about 220 which to me would indicate my fan "alone" (temps stay at 175-185 while driving normally) won't hold up to sustained stop/crawl traffic if I am in it for 30 minutes which is a very rare occurrence for the 67

If the 7 blade does put out more cooling I would swap one in
 

·
Premium Member
Joined
·
403 Posts
I use the 7 blade with a Cold Case aluminum radiator, no over heating problems what so ever
 

·
Registered
Joined
·
1,740 Posts
Discussion Starter #6
My ? is if anyone knows if a 7 blade puts out more cooling, CFM, than a 5 blade

unlike electric fans which publish cfm, not finding any data on mechanical fans other than notes about a wider blade makes more airflow than a narrow blade....which would suggest the wider 5 blade fan would put out more cfm unless the higher quantity of a 7 blade with narrower fins puts out more CFM than 5 wider blade fan

I know electric fan CFM is based on a fixed steady RPM where mechanical is based on engine RPM...but would assume the fan design be it quantity of blades or size/shape dictate what its output is
 

·
Premium Member
Joined
·
403 Posts
My ? is if anyone knows if a 7 blade puts out more cooling, CFM, than a 5 blade

unlike electric fans which publish cfm, not finding any data on mechanical fans other than notes about a wider blade makes more airflow than a narrow blade....which would suggest the wider 5 blade fan would put out more cfm unless the higher quantity of a 7 blade with narrower fins puts out more CFM than 5 wider blade fan

I know electric fan CFM is based on a fixed steady RPM where mechanical is based on engine RPM...but would assume the fan design be it quantity of blades or size/shape dictate what its output is
According to DeRale (a fan producer) it would depend on the pitch
My ? is if anyone knows if a 7 blade puts out more cooling, CFM, than a 5 blade

unlike electric fans which publish cfm, not finding any data on mechanical fans other than notes about a wider blade makes more airflow than a narrow blade....which would suggest the wider 5 blade fan would put out more cfm unless the higher quantity of a 7 blade with narrower fins puts out more CFM than 5 wider blade fan

I know electric fan CFM is based on a fixed steady RPM where mechanical is based on engine RPM...but would assume the fan design be it quantity of blades or size/shape dictate what its output is
 

·
Premium Member
Joined
·
403 Posts
According to DeRale it depends on the style and pitch of each fan, if they are the same then the 7 blade would move more air do to more surface.
Hope that helps
 

·
Registered
Joined
·
2,845 Posts
Had the same discussion with a fellow Camaro restorer. 2 fans as you have described and suggested that the 5 wider blade works best. I have that fan in a 69 BB with AC, stock radiator and shroud and in 10 years never had and overheating problem even in traffic with 95 degree heat. Even in 1970 with my BB Chevelle . . . .never had an issue with stock set up and high heat. It seems when guy add stuff that is not stock they have issues. . . .oh well just an old guy talkin.
 

·
Registered
Joined
·
1,740 Posts
Discussion Starter #10
Had the same discussion with a fellow Camaro restorer. 2 fans as you have described and suggested that the 5 wider blade works best.
same conclusion with my Mopar friends on the 5 vs 7...they said 5 blade also

Wanted to run this across to people on this forum also, thanks
 

·
Registered
Mike
Joined
·
443 Posts
I can't answer the 5 blade vs 7 blade question, but I agree with LeeC that blade style + pitch probably effect air flow the most.
What I can contribute is that I have been using my original GM 19.5" - 7 blade clutch fan and a 21" diameter fan shroud that were included with my car (74 Nova). I also installed a Hayden 2747 heavy duty clutch fan. This combo definitely pulls a ton of air thru the radiator at idle (850 rpms).
264110

In addition to the fan assembly, I also have a Summit universal fit 2 row - 1" tube aluminum radiator (31" wide) and a high flow water pump with a 180° high flow thermostat.

This set-up keeps my 500 HP, 400 sbc at a max coolant temp of 180°-185° no mater where/how a drive the car. I recently took my car for a long drive on a 98°-100° day on both the highway and stop & go traffic (stress test). My coolant temp was steady at 175°- 180° on the highway and never went above 185° during 30 mins of stop & go traffic. After this long drive, I even let my engine idle in the driveway for 15-20 min and the coolant temp never went above 185°. I believe my ignition and carb tuning also play an important role to my consistent coolant temps.

If interested (and the diameter of your fan shroud can accommodate), below is link to a replica of the fan I am currently using.
Link to the clutch fan.
 

·
Registered
Joined
·
1,740 Posts
Discussion Starter #12
Thanks for the comments RifRaf. I have 18" fan, 19" shroud so your 19.5" fan won't work for me. I have the 3 row 23" radiator and clutch, made in USA, IDK if its a Hayden though

Your 7 blade blades look wider and with more pitch than the 18" x 7 blade link I posted

The 5 blade asymmetrical fan I have, IIRC, I bought from Ricks when I went to a fan clutch from my fixed 4 blade fan
 

·
Registered
1968 Camaro RS/SS
Joined
·
90 Posts
I chucked the noisy flex-o-lite I had into the garbage can. That was the right decision.

It took me a few go-rounds because I have a reverse-rotation water pump on my ZZ4/350. I settled on a Dorman 612-108 455mm (18") Dia., 5-blade, Reverse Rotation Fan with a Hayden 2785 Severe-Duty Fan Clutch. I step-drilled the too-small female pilot to 0.750"dia. X 0.125" deep to fit the hub.

Amazing cooling performance. Not overly loud. 100F+ with the AC on and my foot in it - no problems. The engine stays right around 185F.

264126
 

·
Registered
1968 Camaro RS/SS
Joined
·
90 Posts
I ended up using the Hayden 1705 Rev rotation on mine
I wonder if that would have been a better choice for me. The flange is a bit small in diameter on my 2785. Although, the pilot hole on the 1705 is still too small for my water pump hub.

There are so many specs it hurts my head to compare!

Here is Hayden's charts for anyone wishing to get a migraine:
Hayden Catalog
 

·
Premium Member
Brett - Leander, Texas 1969 SS396
Joined
·
1,427 Posts
I ended up using the Hayden 1705 Rev rotation on mine

Resized_20190913_105103 by F G, on Flickr

Damn, you guys just turned the light bulb on in my head! I installed a CVF Wraptor serpentine belt system, which has a reverse rotation water pump. I did NOT remember that I have an OEM fan! Your part number I searched for came up as the clutch for the fan. Do you have a part number for your fan? I want to look at both yours and TomcatSTL's fans before I decide which one to get. I also had one HELL of a time getting the fan assy on due to lining everything up with one hand, lol. This time I am tempted to make threaded studs so I can screw two in before mounting the fan/clutch.
Thanks!

Brett....

264159
 

·
Premium Member
Brett - Leander, Texas 1969 SS396
Joined
·
1,427 Posts
Thanks for posting that. Now I see that there are reverse rotation clutches! So it appears that I need to purchase both the fan and the clutch due to now using a reverse rotation water pump?

Brett.....
 
1 - 19 of 19 Posts
Top