This is a diagram i drew up, the fan stays off till a certain temp then comes on low, then if the engine heats up enough it will shut off the low speed as it turns on the hi speed. One diagram has A/C and the other is with out.

 

I have a 12si 94amp on it now, sucks at idle with the march pulleys BTW. I have a cs130 iceberg 140amp on the way and the mark 8 fan. I also have the part numbers for a smaller alt pulley and larger crank pulley from march in case the idle speed thing becomes a problem with the new alternator. I havent found anything that confirms that the low speed needs to be de-energised when the high speed is on so I am assuming it wont hurt anything, but you know how that turns out.
I do plan on turning the fan upwards to the engine some how, even if I have to mount it to the factory shroud (without extension) or some replication of it to get more of that air flow into the engine compartment so the pressure will push the heat out the side vents like they are supposed to do. I will probably move my breakers and relays up front behind the lights or to the fan shroud and away from side of the engine bay so the header heat doesnt creep up to them in the future.
Just think, all this cause one glitch that lasted less than 2 minutes.
Reminds me of how most get started on thier restorations, "while I'm at it".

 

Aktbird, thats a well thought out schematic you made. Electronics background? I have my current system wired similar to this for my #2 fan with the a/c. that should be helpful to many who want to do this.
I plan on using tyco/bosch power relays with dual diode supply inputs due to the high amp kick in from this new fan (on High) and 80 amp auto reset breakers.
waytek pt nos(relays 75552, breaker 46933)
Have you wired yours up yet? hows is it working out for you?

 

I would mount the fan flat to the radiator without trying to turn it up towards the motor. I live in Tucson, AZ and the temps here in the dead of summer can be 115* ambient temp, no idea what the real asphalt temp is at any given time. Alot of articles have been done about frying an egg in a pan, on the sidewalk, so hot, damn hot. My big block doesn't overheat with this set-up. I am using a DeWitt's aluminum radiator in my set up.
Oh, BTW, I didn't make a shroud for the sides of the fan, where it doesn't cover the radiator completely. It's only aobut an inch or so on both sides.
I don't ever get over 215* at a light, stopped for 2 or 3 light cycles in heavy traffic. I have had half of my seat sucked up my rear end on the first few times I took this out in the summer.
All is well, and should be for you too. Good luck, let us know.


Tank

 

Thanks Tank,
And I hope you get that seat up your butt thing worked out, (JK, I couldnt resist that one).

 

That is no longer a problem, I went to the VA hospital and had a sphincter reverse angle job done. It's an "outgoing only" valve. Took care of the seat up the butt, Bob!!



hahahahahahaha
BBTank

 

WAAYYY too funny Tank!

 

Well, Got the fan in, It is a single speed mark8 fan. Both inputs (+) make it turn though but no noticable difference in speed. I wired one to the a/c and the other to a temp switch. Also installed the iceburg alternator (cs130 @ 140amps) and rewired everything under the hood. Worked okay sitting in the garage but havent had a chance to drive it yet so testing will come in the next couple of days.
One note: That thing blows ALOT of air, I didnt tilt it and the cross flow from the fan seems to swirl enough air under the hood to solve my problem at this point. Time will tell.

 

Going to be mounting an electric fan or 2 in mine shortly. Ill be dropping in an aluminum radiator, a 383, and running headers to factory side exhaust so I'm really interested to see how this plays out. As I read through the posts i was thinking maybe a fabricated duct off the back of the fans to redirect the air up, v/s tilting the fans. Nothing huge just a small shroud type scoop. Even something you could pop off when you get to the cruise-in or show, if you don't want it seen. VETTEVIC, I divide my time between Tampa and Ft. Myers would love to stop by and check out your setup some time...

 

I have thought the same about under hood temperature.
I have not had the problems with the any circuit breakers.
I installed duel Spals a couple of years ago on my 73 with a 400 CID that likes to make heat. I have found during the summers when driving down the road the coolant temperature is 185 F when I stop at a light or driving slow in traffic the coolant temperature raises to 200 F. I think this is due to angle of the radiator and the electric fans mounted against the radiator that are blowing air under the oil pan and not back over the motor as the stock fan set up would causing engine compartment temperature to rise when stopped or moving slow. I tried to alleviate this problem of engine compartment temperature rise by installing a 4” fan by the location where the vapor canister is on the driver’s side and running 4” duct by the master cylinder for intake and exhaust the air at the rear of the lower fender shield. It switches on when the Spals start and is actuated by the same temperature switch.
Just wanted to see if pulling the heat out of the engine compartment had any effect overall.
The fan I installed will pull 250 CFM, the fan housing is 4” dia. X 5.75 long
A cheap experiment less than $30.00

I drove the car after I installed the fan, the outside air temp mid 90 F and monitored the engine compartment temperature. The surface temperature of the hood dropped by 20F and the engine cooled much faster. I think I will leave the fan on for now.
Still looking for other options.

I will be looking forward to an update on the Mark 8 fan you installed.
If it works out well for you I might have to try one and get rid of the three that’s running now.

 

I checked my underhood temp a couple of weeks ago just to see what was happening under there as the ambient temps around here are really starting to go up. i did not get stuck at any traffic lights , just cruising around. i had a stable reading of 159*. i don't know how hot is too hot but that should be getting close. water temp was a steady 185 A/C off. I also noticed here lately when i set in traffic the temp starts to creep up, didn't do that with cooler ambients. I'm running 2500 cfm electric fans , same angle as radiator.ZZ502 with cast iron exhaust manifolds. by the way my temp probe was just in front of the fuel bowl on the carb, not touching anything but air. I have been toying with the idea of putting the stock fan back in just to get some air moving closer to the top of the engine.

 

If the breakers you are using are bi-metallic you have to remember they trip on heat rather than the amp draw. You should go to a fuse or a electronic trip unit rated at 100 percent not the 80 percent ones.

 

G'day,
I've had a single 16" electric fan on my '74 for a few years now, but mounted on a CLOSE FITTING FULL shroud that I made myself. All of the air that enters the radiator goes into the shroud and out through the fan. Engine heats up, fan comes on, temp drops, fan turns off..........etc........etc.

Fan is parallel to radiator and blows air under engine. To mount the fan vertically would surely blow hot air at the carburettor, not what I'd call ideal. I also have a cylindrical finned trans cooler mounted transversely at the front of the crossmember, so that the (hot) air that goes through the radiator fan blows over it. Haven't had it out in hot weather to try it out yet. Winter here now. Brrrrrrrrrrrrrr! I'll be in LA in four weeks

Regards from Down Under

aussiejohn
3 weeks to go

 

Heres some pics of the setup:
fan and alternator, top of the fan has a polished aluminum cover. Still had to make a new arm for the alt bracket any way.

100amp breaker from the stater lug, goes to two 75amp power relays on the bottom of the fan shroud.

Sides of the fan has rubber seals (inner fender top seals) to seal to the radiator.

View down from right side

View of hood up, why I wont be cutting into it anymore.

Also cleaned under the car some


Aussiejon- I dont worry too much about hot air into the carb cause of the cold air itake from the hood.
dtamustang- I checked the temps under the hood once but the thermometer only went up to 220 deg so it was a mute point when it pegged after a run on the highway.
Myred69- I thought about diverting the air afterwards but it also cuts down the cfm it is able to pull, plus to make it sturdy it needs to be more permanent and I do show it often so thats out. But, luckily it is large enough and blows enough air that it spreads out just behind the fan and actually appers to blow up where I need it to blow in the area of the alternator. Thats where the fan relays/breakers were before this change (and where the light circuits are still) real close to the no 1 cyl header pipe. As far as stopping by, be glad to have ya. Just have to pick a day when the rains not a threat and there is a show to go to. Maybe on a Thursday when there is a meet at Old Chicago so we can eat some pizza. Just let me know ahead of time and we can set something up.