Why Ford Changed the Fan Mount in '42

[drolston]

Everything is cool while driving, but my '41 coupe with 284 flathead wants to go full hot during extended idling on a warm day. Using a temp gun on the radiator right under where the top right hose dumps into the top tank, after about 10 minutes it stabilizes just over 200 degrees. Looking into the top tank, I noticed that the water flow looked pretty puny, so I took out the 190 degree disk type thermostats. The water flow is now very robust, but all that did was take longer to get full hot.

The radiator is a new Champion aluminum, rated at 500 horsepower, so there is plenty of cooling capacity. Plenty of water flow; good radiator; - that leaves air flow as the suspect. Got that big 6 blade fan mounted directly on the crank, but at 650 rpm, it will not even hold a sheet of notebook paper to the front of the radiator. Running the engine up to 1500 rpm for a few minutes brings the temp down from full to hot, but not down to a normal range. The fan hub is 2 1/4" from the radiator, and the blade leading edges are further than that; like 3" for the top blades. Some '41 owner please confirm that is correct.

The timing adjustment on Pertronix crab is advanced 3 degrees with no pinging at all; should I advance it some more?

I do not have the skills or tools to fab a shroud, so unless someone has a better idea, I am headed for a very non-traditional-hot-rod electric fan, because this car and I are bound for long trips that will definitely find some traffic jams.

[Alaska Jim]

How far from the radiator is your fan. with no shroud, the fan should be no more than 3/4 of an inch from the radiator core in order to pull the correct amount of air. do you have all the sheetmetal "shrouds in front of the radiator that directs all the air coming through the grill to be "funneled "through the radiator. if not this could be one of your problems. maybe there are some "barners" near you that could help with some fabrication for a shroud.

[corvette8n]

My fan blades edge is 15/16 from the radiator on my '41 coupe.

[Charlie ny]

At Flat Jack's suggestion I installed a shroud on my '41 1/2 ton , I used a Walker shroud
with excellent results. The Walker part is heavy black plastic and you are given instructions on how to cut the fan clearance hole to satisfy the application. I'm using
the original radiator and a 5 blade crank mounted fan. The rag hangs on now. I must
say that unless you took a magnet to it there's no way you'd even guess the thing was plastic.
Charlie ny

[flatjack9]

Yep,it worked wonders on my 39.

[drolston]

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Anything to avoid the non-traditional electric fan! I ordered a simple wrap-around shroud from Speedway for $29.99. Had to go with the 5 1/2" deep version, since my blade tips are 4" from the radiator. I will report back on this thread after installation and test.

[1931 flamingo]

Is there any way for you to get the fan CLOSER to the radiator (or the radiator closer to the fan??
Paul in CT

[drolston]

Originally Posted by 1931 flamingo

Is there any way for you to get the fan CLOSER to the radiator (or the radiator closer to the fan??
Paul in CT

I could relocate the radiator closer but that would take rework of the mounting holes and support braces. The top hoses would be easy enough to modify for the radiator movement, but the lower hoses already do a pretty tight S turn, and I am afraid moving the radiator an inch and a half would make them even harder to get on and off, and maybe kink them.

Also thought about making an extender for the fan mount to get it closer, but the fan on the '41 is already on a 4" long shaft in front of the pulley, and I worry about keeping the extended assembly centered and balanced.

From what I have read, the shroud would be even more effective in getting more air flow through the radiator core. Should know in a week.

[flatjack9]

The shroud needs to cover most of the radiator surface.

[outlaw]

If you look on line at Summit Racing, Speedway, Jegs, and other street rod or racing oriented car sites, they will have fan extensions available in different thicknesses. Not too spendy either. Bill

[drolston]

Originally Posted by flatjack9

The shroud needs to cover most of the radiator surface.

The shroud purchased covers 250 square inches of a 380 square inch core. I am hoping that is enough to keep it cool at idle. The area outside of the shroud is open, which will allow more air flow through the radiator at speed.

Test report to follow in a week or so.

[drolston]

Originally Posted by outlaw

If you look on line at Summit Racing, Speedway, Jegs, and other street rod or racing oriented car sites, they will have fan extensions available in different thicknesses. Not too spendy either. Bill

I am trying to find out if any will accommodate the 2.75" bolt circle of my fan. If so, I will do both spacer and shroud.

[BillM]

Had to go with the 5 1/2" deep version, since my blade tips are 4" from the radiator.

If you have been reading about shrouds you have probably seen that the fan is generally supposed to be half way into the edge of the shroud. I would think you will need to trim that 5 1/2" dimension.

[grumppyoldman]

When I was a teenager, a long time ago I took the thermostats out of my 48 Conv. trying to cool it down. It just got hotter, an old ford man told me the water ran through the radiator too fast and didn't have a chance too cool down. He told me to take the center of the thermostat out and put the washer part back in. That was enough restriction to slow the water down and it worked. My 41 has an extension on the crank too, looks out of place, but I have no heat problems. Don't know what thermostats are in it, been to busy fixing other things. Al

[Johngtate]

Are you any cooler now with the fan shroud installed? I am having a similar issue on my '40 and am curious to see if this helps.

[Seth Swoboda]

Originally Posted by Johngtate

Are you any cooler now with the fan shroud installed? I am having a similar issue on my '40 and am curious to see if this helps.

I recently found out that a perfectly clean radiator (internally) is a must. Any slight blockage of the tubes will increase the temperature. Start with a clean radiator and work outwards. Run 180 degree thermostats also.

[drolston]

Originally Posted by Johngtate

Are you any cooler now with the fan shroud installed? I am having a similar issue on my '40 and am curious to see if this helps.

I have the shroud but have not installed it yet. I will get back to you in a week or so.

[40 Deluxe]

'41 was first year for the six, which is a longer engine. I believe Ford had a forward radiator location for the six and a rearward location for the V8. Maybe Drolston's car was a six originally.

[A bones]

[Quote] The fan hub is 2 1/4" from the radiator, and the blade leading edges are further than that; like 3" for the top blades. Some '41 owner please confirm that is correct.[Quote]

Need to understand. My project has yet to get a fan. Reading this makes me think the fan would push not pull. I am often wrong ( it's on record) So, please tell me.

He did say running fast helps.

[rich b]

Funny how those aluminum radiator guys rate their products to cool hundreds of horsepower; but fall down on 85 or 90 hp.