Electric Aux Fan for Vintage Air

[cowsaredelicious]

I've got a 348 with power steering, power brakes and now AC installed. When I ran it around the other day the ambient air temp was 85 degrees and I was running about 70 mph for ~1 hour and achieved a max temp of about 210. I'm running a 5 blade belt driven fan w/ clutch and it seems to move a good amount of air, however I'd like to get it running cooler. (I'm going to check timing this weekend but it should be fine).

I'm more concerned about running the AC in Aug when we will see several days north of 100 degrees. I'm more or less comfortable with the 210 temp but would like to not exceed this.

I'm opting for an electric fan (or fans based if required for space or cooling efficiency). And as everyone on here knows it's going to have to be a pusher to work in tandem with the engine driven fan already in place. I'm not opposed to changing the radiator either (currently factory) but I figured if I tried the electric fan first and it wasn't sufficient I could still swap out and utilize it if a radiator was required.

Third thing is I understand that there should be a relay utilized to manage amp draw. So any pointers here or examples of what others have done would be appreciated.

Does anyone have a good solution or examples of what has been done in front of the condenser?

 

[Don Jacks]

The "pusher" fan will only help at low speeds[35 and below].If she's running hotter than you'd like at 60-70 mph.,you don't have enough cooling capacity[radiator too small ,or restricted flow].

 

[wristpin]

The "pusher" fan will only help at low speeds[35 and below].If she's running hotter than you'd like at 60-70 mph.,you don't have enough cooling capacity[radiator too small ,or restricted flow].

A factory fan shroud is more important than you realize. If you dont have one atleast get something that will do a similar job. You can also install a lower opening temp thermostat such as a 175 unit if you have a 195 or 205. Before installing that thermostat drill a 1/32-1/16" hole on the flat part to create a constant flow through it to help it warm and open sooner. If that and probably a few other suggestions dont help then go get that cooling fan. I've used them with a cheap open/closed temp sender that acts as my ground to complete the circuit. Ive also just had a switch that i turned on and off. Cuz im cheap. Oh and that electric fan will be 12V so find sufficient amperage off your fuse block or install one in a waterproof location. Good luck.

 

[Geary Trussell]

You will need an electric fan for the a/c condenser to keep the head pressure in check and for low speed/in traffic performance. Sucker fan is best but if you want to use your engine driven fan a pusher fan will do. Be sure to have good heavy wiring and a good quality fan relay.

 

[cowsaredelicious]

Ok, so I know I'm going to open up a big can here but I pulled the thermostat sometime last year, now I'm going to swap it back tonight, I know there is a lot of back and forth and (https://www.jalopyjournal.com/forum/threads/running-without-a-thermostat-educate-me.63635/ ) covers it in great depth so I'm going to try it again, betting on the flow restriction idea and I'm in agreement that large corporations typically don't design additional parts for fun. My initial thought was that the thermostat was only a function of warming the engine up quicker and since my '60 doesn't see cold weather it didn't have a function. nonetheless it's going back in...

My follow-up question is actually this; Would there be any detriment to building a better fitting fan shroud? All aftermarket aux fans use a flat piece over the radiator to ensure it draws directly through the fins (minimizing air turbulence i would guess). see picture for example

I fabbed it up already but neglected to take pictures so I'm using the attached picture as a close representation. I made mine out of 20 ga steel and have it bolted onto the existing factory fan shroud, so it can be removed if it doesn't produce the desired effects. My thoughts are this...it would ensure that nearly 100% of the draw created by the 7 blade fan (non-flex) to pull through the radiator/condenser, however it might create "hot spots" on the edges since the fan is centered and doesn't cover the entire finned area. I guessing there is a net gain in overall cooling but temp variation in the radiator as different spots would cool less efficiently.

Another thought as I understand it is the fan clutch disengages based on an achieved temperature bi-metal mechanical disengagement. two question on this, is there a way to test w/o crawling under the hood at 70 mph? and while there might be a efficiency loss what is the issue with removing a clutch altogether? If it runs all the time at higher RPM wouldn't that generate more CFM at all speeds?

 

[Cayneman]

Pusher fans restrict airflow. I would never consider using them. The car in my avatar runs a steel engine driven clutch fan with a shroud and Vintage Air with no problems what so ever. Remember the Cooling Rule Of Thumb. Runs hot at highway speed - not enough radiator. Runs hot at low speed - not enough fan.

Gary

 

[boxerdog]

I think the shroud could help, but it might need some "flappers" to vent it if the internal pressure was too great at highway speeds.

 

[Cayneman]

Did original shrouds come with flappers?

Gary

 

[boxerdog]

They didn't seal off the radiator completely, so they didn't need them.

 

[models916]

That opening in the manifold needs some restriction to force water into the small voids in the engine. Depending on the impeller on the water pump, the small restriction will keep the pump from caveating. Stock 409 gm water pump impeller has a backer molded and is a serpentine type that will not cavitate. Not sure what the aftermarket or the rebuilt units will have. Drill a small hole in the flat rim on the thermostat to bleed air.

 

[El Rat]

What temp does a "box stock" 409 generally have. I mean an original un-modified car. I'm thinking about 185-190 at speed in 90 degree ambient...what say you?