Bigger Radiator Upgrade for 65-66 Mustangs

20" , 4-ROW CORE RADIATOR in a 65 Mustang

These can be found in: 67-69 Mustangs - lower hose on passenger side 70 Mustangs - lower hose on driver side Fan shrouds available through Mustang vendors

Here are some shots of my 65 coupe engine compartment showing the bigger radiator installation. I used a 1969 4 row - high efficiency core radiator and the 69 fan shroud with a clutch fan and an 8 blade flex fan. It never gets hot, even in 100 degree weather, in traffic, with the a/c on!.  It pretty much bolted right in...with a few mods.
 
First, I cut 1-1/2" from each side of the hole in the core support. (You don't HAVE to CUT - it will fit but the outer two rows of core will be blocked) Then spaced the radiator up off the frame with 1/4" wood spacer (will be removed after bolted in). Then drilled new holes for the 4 bolts holding the radiator in the car. They worked out to be exactly even with the existing holes that were removed when the core support was trimmed. I "percussion engineered" the core support a bit to move the mounting flange forward about 1/4" to allow for the radiator's extra thickness. The fanshroud bolts directly to the radiator, after drilling 4 holes. If you use a 3 row radiator, the holes are already there.  Then the clutch fan and new clutch were bolted on.  Now I have a 4 row, 20" wide radiator in place of the old 17" wide 3 row job. And I now have a fan shroud that actually works.  My fan is a 17-1/2" 8 blade type, but I think an 18" would work even better.

I had to make some new brackets for the A/C condenser as it had to be pushed forward about 1/2" and the original mounting holes were no longer in the core support. I also used a 70 model battery tray and fender apron to reposition the battery 90 degrees. This is not absolutely necessary if you trim the hold down clamp flange off the original 65-66 battery tray. Mine does have more room though.

24" CLAMP-IN STYLE 3-ROW CORE RADIATOR in a 65 Mustang

These can be found in: 67-69 Mustangs – lower hose on passenger side 70 Mustangs – lower hose on driver side Shrouds are available new through MustangSteve for $90+ shipping

Battery tray is modified using the brace from under the 65-66 tray and the top shelf part from a 67-70 tray. This will allow the wider radiator to fit and also allows use of the superior 67-70 battery clamping system. You can use the long studs on both sides of the battery or do as I did and use a bolt into the radiator core support for the front side. That is a simple flat peice of steel across the top. I used some thin rubber under the steel so it could not slide. The Proxima battery with rounded corners is much easier to install. Square batteries require the radiator top clamp to be loosened and the radiator slid to the side a bit in order to get the battery in the tray. Hoses need not be disconnected.

Radiator fits like it was meant to be there. Upper clamp is from 67-69 Mustang or Cougar Lower clamps can be fabricated or modify some from 67-70 Mustang with 24" radiator. Make them so the bottom of the radiator just barely clears the frame. Rubber clamp inserts are available through Mustang parts vendors, or you can just use some strips of heater hose or insulation.

If your car has air conditioning, the outlet tube won't clear the wider radiator. You will need a condenser that has the driver side fittings pointing straight down. Good news is there are some aftermarket units available for around $100 that are larger than the stock original and will fit perfect. Use an inline drier and route the hoses down below the front valance to hide the drier. New hoses,custom made for your car are less expensive than you would think. I had all my hoses made from scratch for under $100. Voltage regulator must be moved about 2" towards the fender

This shows where to cut the core support. This is best done with a nibbler but just about anything that cuts will work.

Battery tray is modified using the brace from
under the 65-66 tray and the top shelf part
from a 67-70 tray.  This will allow the wider
radiator to fit and also allows use of the
superior 67-70 battery clamping system.  
You can use the long studs on both sides of
the battery or do as I did and use a bolt into
the radiator core support for the front side.  
That is a simple flat peice of steel across the
top.  I used some thin rubber under the steel
so it could not slide.
The Proxima battery with rounded corners is
much easier to install.  Square batteries
require the radiator top clamp to be
loosened and the radiator slid to the side a
bit in order to get the battery in the tray.  
Hoses need not be disconnected.

You can see from this picture why the shorter battery tray is needed