The Ford Barn

aussie merc · 03-13-2026, 04:07 PM

looking for factory fan to radiator core clearance as have had a custom rad made that deleted the 4th row of cores but increased the surface by 35% vehicle is 39 mercury also thought about fitting fan ring or making a shroud [not an easy option due to crank fan and lower cooling pipes ] not a lot of clearance

19Fordy · 03-13-2026, 05:19 PM

Photos please.

ford38v8 · 03-13-2026, 10:55 PM

Aussie, I don’t understand how 3 rows can have 35% more surface than 4 rows. Please explain?
Fan proximity to radiator ( without a shroud) should be no more than an inch. With a shroud, the important relationship is fan to shroud, the trailing edge flush with the shroud. The crank mount fan was not one of Ford’s better ideas, but a shroud can prove to be the best use of your new radiator.

aussie merc · 03-14-2026, 03:26 AM

radiator is taller and wider hence the increase in the frontal area also buy the time that the airflow finds its way back to the forth row its already absorbed about as much heat as it can so the forth row does very little also the tubes are 3/4 against the standard 1/2 so the actual capable coolant flow is higher add to that 14 fin per inch against 8 fin per inch so technically and on paper you can cool a big block with it just trying to optimize what i have as we suffer with a normal heat range of neg5C to 40+C winter/summer

Bored&Stroked · 03-14-2026, 04:10 PM

From everything I've ever heard, the closer to the radiator core, the better. I usually try to shoot for 1/4" or so.

rotorwrench · 03-14-2026, 04:50 PM

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Air flows pretty fast through the radiator at speed. Its depends on fin count too. Those crank mounted fans turn slower but have more blade surface area than belt drives. I've not heard too many complaints from 39 deluxe or 40 Ford owners about problems with overheating as long as the cooling system is clear. I don't know a lot of 39 or 40 Merc owners so I don't know about them. They should be about the same as post war cars as far as reliability.

aussie merc · 03-14-2026, 04:59 PM

cooling systems seem to be ok in cooler climates as owners in tasmania dont report any problems it only seem to be where you get the wider swings between summer and winter that this problem raises it head

aussie merc · 03-14-2026, 05:42 PM

by the way the factory fans may be six blade but due to the fact they are duel diameter [ factory fix to get rid of fan drone ]they struggle to make that big a differance with a shroud or ring as only 3 blades are close enough to the opening to have any effect

03-13-2026, 04:07 PM	#1
aussie merc Senior Member Join Date: Sep 2016 Location: sydney australia Posts: 1,156	fan clearance looking for factory fan to radiator core clearance as have had a custom rad made that deleted the 4th row of cores but increased the surface by 35% vehicle is 39 mercury also thought about fitting fan ring or making a shroud [not an easy option due to crank fan and lower cooling pipes ] not a lot of clearance

03-13-2026, 05:19 PM	#2
19Fordy Senior Member Join Date: May 2010 Location: Coral Springs FL Posts: 11,916	Re: fan clearance Photos please.

03-13-2026, 10:55 PM	#3
ford38v8 Senior Member Join Date: Jul 2011 Location: SF Bay Area Posts: 7,634	Re: fan clearance Aussie, I don’t understand how 3 rows can have 35% more surface than 4 rows. Please explain? Fan proximity to radiator ( without a shroud) should be no more than an inch. With a shroud, the important relationship is fan to shroud, the trailing edge flush with the shroud. The crank mount fan was not one of Ford’s better ideas, but a shroud can prove to be the best use of your new radiator. __________________ Alan

03-14-2026, 03:26 AM	#4
aussie merc Senior Member Join Date: Sep 2016 Location: sydney australia Posts: 1,156	Re: fan clearance radiator is taller and wider hence the increase in the frontal area also buy the time that the airflow finds its way back to the forth row its already absorbed about as much heat as it can so the forth row does very little also the tubes are 3/4 against the standard 1/2 so the actual capable coolant flow is higher add to that 14 fin per inch against 8 fin per inch so technically and on paper you can cool a big block with it just trying to optimize what i have as we suffer with a normal heat range of neg5C to 40+C winter/summer

03-14-2026, 04:10 PM	#5
Bored&Stroked Senior Member Join Date: Jan 2011 Location: Central Ohio Posts: 5,906	Re: fan clearance From everything I've ever heard, the closer to the radiator core, the better. I usually try to shoot for 1/4" or so.

03-14-2026, 04:50 PM	#6
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 18,006	Re: fan clearance Sponsored Links (Register now to hide all advertisements) Air flows pretty fast through the radiator at speed. Its depends on fin count too. Those crank mounted fans turn slower but have more blade surface area than belt drives. I've not heard too many complaints from 39 deluxe or 40 Ford owners about problems with overheating as long as the cooling system is clear. I don't know a lot of 39 or 40 Merc owners so I don't know about them. They should be about the same as post war cars as far as reliability.

03-14-2026, 04:59 PM	#7
aussie merc Senior Member Join Date: Sep 2016 Location: sydney australia Posts: 1,156	Re: fan clearance cooling systems seem to be ok in cooler climates as owners in tasmania dont report any problems it only seem to be where you get the wider swings between summer and winter that this problem raises it head

03-14-2026, 05:42 PM	#8
aussie merc Senior Member Join Date: Sep 2016 Location: sydney australia Posts: 1,156	Re: fan clearance by the way the factory fans may be six blade but due to the fact they are duel diameter [ factory fix to get rid of fan drone ]they struggle to make that big a differance with a shroud or ring as only 3 blades are close enough to the opening to have any effect