Flex-A-Lite Custom Radiator Install
Ensure your engine swap keeps its cool with a special-order radiator solution from Flex-a-lite
From the January, 2013 issue of Modified Mustangs & Fords
By Mark Houlahan
Photography by Mark Houlahan
Even though our radiator was built from our specs to fit, there is still a fair amount of mock up work to do to finalize everything.
If you have a 1968 Mustang with the typical small- or big-block Ford engine offering between the framerails, you can source a direct-fit bolt-in radiator from one of a dozen or more different sources. A few days later, a big brown truck pulls up to your driveway and drops off your shiny new thermal transfer unit—it will probably take you less time to bolt it into your Mustang than it will to get it out of the shipping box. However, things change when you start deviating from stock. The most basic of upgrades, like a serpentine pulley setup, for instance, might relocate the water pump inlet from one side of the block to the other. Uh-oh, your stock radiator no longer works. A solution might be as simple as a custom lower radiator hose. There are a few "custom" radiators on the market for the most popular upgrades like '87-'93 5.0L Mustang engine swaps, but when you really start “going wild,” your best option is going to be ordering a custom radiator to work with your choice of engine and other major mods.
In the case of our project 1968 Mustang fastback, Generation Gap, we not only have a 4.6L Three-Valve modular engine under the hood, but we no longer have the OE strut rod mounting brackets welded in place either (which are used to mount the bottom brackets for the larger big-block radiator setup). We wanted an OE fit to our radiator that would allow us to use our stock modular engine cooling hoses, fit the '68 Mustang's radiator opening, and of course, have plenty of cooling capacity while using an electric fan—there's no provision for an engine-driven fan with 4.6L Three-Valve Mustang engine. We've used direct-fit products from Flex-a-lite before and have been extremely pleased with their hardware, fit, and cooling ability, so they were on our short list of companies to touch base with. When we found out they have a custom order program to build a radiator exactly to your project's specs, that sealed the deal for us.
We got on the phone to Flex-a-lite's David Heutmaker to discuss our needs. After taking a few measurements, David recommended Flex-a-lite's 52180R universal radiator as a base for Flex-a-lite's custom shop to build from with our needs (inlet/outlet sizing and location, and so on). As you'll see in the photos, David's recommendation was spot on.
Flex-a-lite's radiators all begin with a two-row, all-aluminum core—down flow and cross flow, as well as a dual-pass cross flow, are all options. Side tanks are built using the company's patented Flex-a-fit T-channels that not only help dissipate heat by increasing surface area (both inside and outside the tank walls), but allow custom mounting solutions that do not require welding brackets in place. The T-channels also allow custom mounting of additional accessories like overflow tanks, cooler mounting rails, and more. Best of all, Flex-a-lite's radiators are all proudly made in the USA and are welded by hand for great looks and top quality, fit, and finish. Turnaround time on a custom radiator is a couple of weeks, plus shipping to your location, but the end result is a radiator that fits your one-off application like a fine Italian leather driving glove!
|Cooling System Part Numbers Used
||$247.94 (4116-6 without fan, $55.98)
|Accessory Bracket kit
|180 Fan Switch
|20ft of -6 PTFE hose
|-6 AN 45 Fittings
|Total Cooling System
||$1,384.66 ($1,192.70 with 4116-6 cooler)
1. Flex-a-lite made sure we...
1. Flex-a-lite made sure we had everything we’d need to keep our engine and transmission cool. We have our custom-built radiator based off of its 52180R part number with a Flex-a-lite 15-inch Black Magic Xtreme S-blade electric fan, universal mounting brackets, a fan controller with wiring, an accessory rail kit, an external remote transmission cooler, and its exclusive Gator Clamps for retaining coolers and hoses.
2. Our engine bay is pretty...
2. Our engine bay is pretty full now that the 4.6L Three-Valve is in place, and we’ve been working on the wiring in our spare time (what little we have). One place we have copious amounts of room is the radiator mounting and core support area. We took measurements of our core support opening, width between the framerails, and more and filled out Flex-a-lite’s four-page, custom order sheet.
3. We didn't want our new...
3. We didn't want our new aluminum radiator sitting directly on the lip of the core support, so we fashioned some simple shims/spacers out of cardboard until we had about a half-inch gap configured and taped them into place for the radiator to sit on while we mocked up the mounting brackets.
4. Before our initial test...
4. Before our initial test fit, we fitted one of Flex-a-lite’s sacrificial zinc anode kits in the drain port of the radiator. This little guy will help prevent corrosion with our aluminum based cooling system.
5. Flex-a-lite recommends...
5. Flex-a-lite recommends the widest core you can fit in your OE radiator opening to maximize cooling efficiency. The widest core we could use was 22 inches; however the overall size becomes 27� inches with the Flex-a-fit tanks, putting us over our framerail measurements by just a hair. The solution—we had Flex-a-lite mill off the bottom 3 inches of the fins for clearance.
6. The universal mounting...
6. The universal mounting brackets included with all special order and universal radiators offer mounting slots for the Flex-a-fit channels and for your core support. While we’re not averse to grabbing the drill, we were pleasantly surprised to find out the mounting bracket slot spacing was identical (within a few hundredths of an inch) to these square holes stamped in our core support!
7. The mounting brackets were...
7. The mounting brackets were attached with the included hardware, though we did use some steel spacers we made up from small tubing along with longer mounting bolts for the upper holes to ensure the radiator was parallel to the core support opening, and that the radiator didn’t touch/rub the core support. We only used one T-bolt per side for this mock up.
8. With the radiator held...
8. With the radiator held in place temporarily using the minimum of hardware, the upper and lower hoses and engine inlet hose and air filter were installed to check for fit and clearance. Other than the stock upper radiator hose needing a few inches trimmed from its outlet, everything fit checked fine.
9. To finalize the radiator...
9. To finalize the radiator side bracket mounting, we felt it was best to pull the radiator from the car and finish the installation of the brackets on the workbench. Starting with some painters tape, we marked the location of the bracket and used a grease pencil to mark the remaining T-bolt locations.
10. The T-bolts simply slide...
10. The T-bolts simply slide down the Flex-a-fit track like so, allowing for endless mounting options. Once we had the four T-bolts in place (per side), the radiator mounting bracket was relocated with the help of our tape guide and secured with the included nylon locking nuts.
11. Once we had the four T-bolts...
11. Once we had the four T-bolts in place (per side), the radiator mounting bracket was relocated with the help of our tape guide and secured with the included nylon locking nuts.
12. Flex-a-lite’s accessory...
12. Flex-a-lite’s accessory rail kit utilizes the Flex-a-fit fins to allow easy installation of accessories like cooling fans, oil coolers, and the like. Here, we’ve attached its 22-inch bracket kit, PN 32122, to our radiator in preparation for our external transmission oil cooler.
13. We discussed our oil cooler...
13. We discussed our oil cooler needs with the techs at Performance Automatic, as well as Flex-a-lite and all agreed that this 16,000 GVW rating TransLife cooler from Flex-a-lite would keep our 5R55S five-speed automatic cool. We installed the cooler to the accessory rails using Flex-a-lite’s Gator Clamps, an easy to use mounting solution that sandwiches the cooler’s tubes.
14. With our mounting brackets...
14. With our mounting brackets and transmission oil cooler installed our custom radiator could be fitted back to our Mustang for good. After bolting the radiator back up to our core support, final inlet/outlet hose fitment was made. Our lower hose, shown here, fit perfectly with no trimming.
15. While our upper hose fit...
15. While our upper hose fit without trimming, it did sit back at an angle, touching the front of the engine. We chose to trim about 3 inches off of the hose end to clean the routing up a bit and make the upper hose parallel with the radiator, as you can see here. With the engine’s filter and inlet tube back in place our one last concern was the gap at the top of the radiator.
16. Knowing that for the radiator...
16. Knowing that for the radiator to do its job you have to ensure the air passes through the radiator core for heat transfer to occur (instead of over or around it), we made this simple sealing dam with a strip of aluminum and some pinch-on foam seal.
17. A few minutes with a drill...
17. A few minutes with a drill and a pair of 1⁄8-inch aluminum rivets and our radiator core support block-off project is a success, ensuring all of our incoming air goes through the core and not bleeds over the top.
18. When you order a complete...
18. When you order a complete cooling solution (radiator, electric fan, and universal brackets) Flex-a-lite specs its standard cooling fan controller with the kit. The controller handles the fan’s power requirements with onboard relays and inputs for manual override and A/C functions, and includes all wiring and terminals.
19. The fan controller’s temperature...
19. The fan controller’s temperature probe is positioned through the radiator core to read coolant temperature. You want the probe as close to the radiator inlet hose as possible, as seen here. The fan controller needs to be mounted close enough to the radiator for the temperature probe to reach. We found it amazingly simple to just position the controller on the radiator’s mounting bracket. However, we will not be using the included controller for this particular project.
20. We've used the Flex-a-lite...
20. We've used the Flex-a-lite fan controllers before and they are rugged devices that allow control of the fan when the A/C is in use or by manual override, but since our 4.6L Three-Valve is controlled by Ford Racing’s Control Pack electronics package all we simply have to do is connect the fan power lead to the fan and let the computer and the onboard relay control the fan via the engine coolant temperature sensor on the engine!
21. We ordered our Flex-a-lite...
21. We ordered our Flex-a-lite TransLife transmission oil cooler with optional AN -6 fittings because we didn’t like the idea of plain rubber hose for transmission lines. A call to Summit Racing for 20 feet of PTFE lined AN -6 hose (the PTFE can take high heat/pressures better than plain rubber hose) and 45-degree AN -6 fittings allowed us to quickly plumb our trans cooler. The aluminum fitting on the upper cooler line is an inline thermal switch from Derale we picked up at Summit Racing to control the small cooler fan.