Distance between mechanical fan and radiator core

[DanLewis]

I was surprised to discover today that the distance from the front of my 6-bladed plastic fan to the radiator core on my Bugeye was almost 4"! It's 5" from the water pump flange to the radiator, and the plastic fan extends another 1" from the flange. Even though there's a fan shroud, it really seemed unusually far.

​

Although I have a Chinese aluminum radiator installed, the mounting and core thickness is absolutely identical to the original equipment radiator that I still have laying around. I don't think there's anything odd about the water pump either - especially since the fan belt lines up properly between the water pump pulley and the crankshaft pulley.

I started looking for a fan spacer and ran across this statement on Summit Racing's website:

Belt-driven fans work best when they are 3/4 in. to 1 in. from the radiator's surface. Whenever you remove an original equipment fan clutch from your engine, you need to add a fan spacer. This will bring the fan back into the "sweet spot" in the fan shroud opening.

(See https://www.summitracing.com/parts/flx-14556)​

I'm now wondering if the large distance between the fan and radiator is diminishing the effectiveness of the fan at idle, contributing to the engine temperature rise I see at idle on a hot day?

Could someone with a Bugeye confirm whether or not the 4" distance between the fan and the radiator core is normal?

Thanks!
Dan

 

[Trevor Jessie]

I have an electric puller fan, so it would be hard for me to get a good measurement. However, I know that there is a significant amount of space there.

 

[AN5Sprite]

Dan,

1275/6 blade fan/stock bugeye rad: I'd call it closer to 3". The top tank limits how far forward the fan can go. (That might not be the case with an aftermarket radiator)

Of course the distance is going to limit the effectiveness of the fan, but.... You don't sit in traffic that much, do you? Long as it doesn't boil over AND the temp drops in clean air, I'd be satisfied.

 

[Gundy]

FWIW....I use an aluminum rad and no blade fan. I had to take a measurement for a friend
from the end of my pulley to the core. 4 and 3/4 inches.
My electric fan is a pusher, in front, and my oil cooler is mounted between the motor and the core.
Plenty of room in there. I have the "improved" water pump and pulley so there is that too.
My 1380 runs cool. Normally going down the road it'll get to about 170 degrees in the summer.
I flip on the fan when it hits about 180, say a steep, hard, mountain pull in the summer.
I always flip on the fan at red lights...just out of habit. Knock it off when light goes green.

 

[bug_sixty]

FWIW....I use an aluminum rad and no blade fan. I had to take a measurement for a friend
from the end of my pulley to the core. 4 and 3/4 inches.
My electric fan is a pusher, in front, and my oil cooler is mounted between the motor and the core.
Plenty of room in there. I have the "improved" water pump and pulley so there is that too.
My 1380 runs cool. Normally going down the road it'll get to about 170 degrees in the summer.
I flip on the fan when it hits about 180, say a steep, hard, mountain pull in the summer.
I always flip on the fan at red lights...just out of habit. Knock it off when light goes green.

All the same here except I have the heater outlet rad. where you put the oil cooler...and the oil cooler is vertical on the opposite side of the fresh air intake....cut out, frame and ducting for air intake nearly the same as fresh air intake just opposite side... lots of hoses....you'd this it was one of those eighties cars under the hood...haha

 

[bug_sixty]

FWIW....I use an aluminum rad and no blade fan. I had to take a measurement for a friend
from the end of my pulley to the core. 4 and 3/4 inches.
My electric fan is a pusher, in front, and my oil cooler is mounted between the motor and the core.
Plenty of room in there. I have the "improved" water pump and pulley so there is that too.
My 1380 runs cool. Normally going down the road it'll get to about 170 degrees in the summer.
I flip on the fan when it hits about 180, say a steep, hard, mountain pull in the summer.
I always flip on the fan at red lights...just out of habit. Knock it off when light goes green.

Opps, I don't have a Alum rad. just a BE without the fan shroud....totally new core....

 

[Trevor Jessie]

David, is your temp sensor in the head?

 

[Gundy]

My stock temp sensor screws into the
radiator like oem. Serck rad provides
a stock threaded bung in the oem
location. The rad does have a nice
shroud.
I don't have a thermal sensor for my
electric fan. Manual switch only.
I watch my dash gauges like a hawk.
Hap's got me paranoid about my
Cooper S type head and over heating.
It is a Longman head but has those large
intake valves and a 21 cc combustion
chamber.
;-)
Runs very cool and I use a thermostat .

 

[Trevor Jessie]

The temps just seemed low, but if the temp sender bulb is in the radiator, then the temps make more sense.

 

[Gundy]

Now there you go...Hap and now you have me paranoid about that head's temp.
You can see the sensor in this pic.
It did get to 210 degrees or so when I lost a fan belt once.
Shut it down immediately. No harm and temps quickly fell with the fan running.
The manual switch is a pull type that lights up red when "on".
Note it is next to the temp gauge. Tacky, but effective.

 

[DanLewis]

All the same here except I have the heater outlet rad. where you put the oil cooler...and the oil cooler is vertical on the opposite side of the fresh air intake....cut out, frame and ducting for air intake nearly the same as fresh air intake just opposite side... lots of hoses....you'd this it was one of those eighties cars under the hood...haha

Could you please post a picture of how you have the oil cooler mounted and the ducting in the bonnet? I was thinking of doing exactly the same - mounting it on the side opposite the heater air intake.

Thanks!
Dan

 

[bug_sixty]

Will do... out of town at the moment...

 

[Gundy]

I like bug 60's arrangement.
I'd also like a catch can in that
area where the window wash bottle
sits. Decisions,decisions.
That breather where the old fuel
pump went can really ...uhhhh...
breathe an oily breath. Not a problem
but I'd really like a catch can.
I do love the functional washer.
It's all a work in progress,eh?

 

[Gundy]

Trevor
I used a digital infrared to check
variance once. I don't remember
the #s but must of been ok.
Dash gauge #s were spot on.
If it quits raining I'll collect some
data.

 

[Slick Willy]

I hate to jump into a thread ,but I must know. With all the talk of heating issues, and reading a lot of older post. My sprite runs about 180 in normal use, 190-195 in the hills and traffic. Would this be normal for a 1275 with a 180 stat? Forgive my ignorance, I'm a newbie and really want to take care of my motor. I see a lot of people using electric fans do they work better than stock? I live in the mountains of KY so not a lot of flat land driving to be had.

 

[Gundy]

I hate to jump into a thread ,but I must know. With all the talk of heating issues, and reading a lot of older post. My sprite runs about 180 in normal use, 190-195 in the hills and traffic. Would this be normal for a 1275 with a 180 stat? Forgive my ignorance, I'm a newbie and really want to take care of my motor. I see a lot of people using electric fans do they work better than stock? I live in the mountains of KY so not a lot of flat land driving to be had.

Sounds fine. Losing the stock fan
is why people use the electric fans.
You are spot on with those numbers.
Ditching the stock fan is a hot rod deal. Tiny bits of HP are used to
overcome the fan's resistance.
Hence...ditch it and spend stupid
$ to work around no motor driven
fan.
A bit of guilty pleasure. Needed ?
Nope. Cool and functional? Yep.

 

[BlueMax]

Photo of Sebring Sprite cooler mounted at the fresh air duct.

 

[Slick Willy]

Thanks Gundy for the input. Blue max I dig the cooler.