by Jim Morrison 3/23/91
This report is on the installation of the Mangum radiator core available from Northside Radiators, 1313 N, Heidelbach Avenue, Evansville, IN 47711, (812-423- 7177). This core has been much publicized in previous TElAE newsletters and CAT shop notes. It was highly recommended by those who tried it with reported reductions in water temperature of 10 deg to 30 deg. But first, let me bring you up to date on what led me to make this purchase. When I bought my Tiger five years ago, it had a 289 with high lift cam, headers, Torker intake mainfold, 10:1 compression ratio, Mallory dual point, etc. and the original, stock radiator. I immediately had overheating problems, so on went a seven blade flex fan, new 160 deg thermostat, new coolant, new radiator cap, but no change. I then pulled the radiator and took it to a local radiator shop to be flow tested. The flow test showed blockage in the tubes. As a brand new Tiger owner, I was not aware of the extremes one sometimes must go through to keep a Tiger cool and thought the problem could be fixed by simply “redding out” the original core. The radiator shop could not rod out the old core due to the severity of the blockage and recommended a new core.
I had a new core installed that was slightly thicker than the stock radiator, but the overheating problem continued. In desperation, I removed the heads to find some badly blown head gaskets. Replacing them fixed things up to make the car drivable. It has never run as cool as I would like, but what Tiger does? After moving to Hunstville, AL. I had a small leak in the radiator. While getting it fixed, the radiator man informed me that my replacement core “was about the lowest quality core on the market”. I have always wondered what a quality core would do for the operating temperature. This brings things up to a few weeks ago. The car was running about 195deg to 200 deg on the highway on hot days. While not too bad, the temperature would creep up fast at stop lights or just around town.
The thought of having a poor quality core being part of my problem, combined with all the good results I heard about the Mangum core, prompted me to make the plunge and ship the radiator to Evansville. I selected the two and three eights inch thick core and asked that they not paint the radiator so that I could paint it as I desired. I received the re-cored radiator back in about ten days. Shipped COD at a total cost of about $240. The workmanship looked good and it was unpainted as I had asked. Now on to the installation. The brackets on the new radiator are mounted in such a way so as to put the extra core thickness forward of the plane of the brackets (in this way the fan-to radiator clearance remains the same as with the stock core thickness and no modifications to the fan shroud are necessary). This necessitates the removal of some of the bulkhead sheetmetal to make room for the core to protrude forward. This was easily done with a metal blade in a jig saw. The big test was driving it on a hot day. Much to my disappointment, the car ran no cooler than before. My conclusion from this is that the radiator efficiency may not be the limiting factor in the operating temperature of my car and/or the “low quality core” does all that the quality core can do. My oil cooler sits directly in front of the radiator and I wondered if it might be blocking too much air from getting to the radiator, so I removed the oil cooler. This actually lowered the water temperature by about five degrees! Well, my radiator saga is over. I am a poorer, but wiser Tiger owner who knows that he has done all reasonable things (short of sheetmetal mods) to get the beast to run cool and maybe some of you can benefit from my experience. (ed note: A non-flex 6 or 7 blade high pitch fan blade would have complemented Jim’s radiator and may have resolved the overheating problem)