[AMC-List] How I identified a bad radiator and choice for replacement in my 70 AMX road racer

[hal.lynch@xxxxxxx]

Hi guys,

I am going through an interesting issue with my 70 AMX road racer and thought I'd share the experience so far and request any input before I proceed.

Back in 1999 I removed my Allison NASCAR engine to refresh and store in favor of a mild 401 that I had built by Ron Waters at WSC.  The engine is a copy of his very successful road race engines.  I copied his extensive road race knowledge to build a second 'mule' motor for my car that I will use for street use, driver training and chassis setup for the AMX.  It basically has been blueprinted, balanced, ported and plumbed for dry sump oiling.  Outside of that it uses all the same accessories of my NASCAR engine.

Once I installed this engine in my car back in late 2003 I immediately had a problem with water temperature creep, where the water temp would just keep rising as it idled.  I shut it down once it reached 210 and scratched my head..  How could a brand new engine running proven accessories that supported a NASCAR engine and never ran hot at all now fail me?

Long story short, I found pretty quickly saw that the radiator was not getting hot, removed it hand sure enough it was plugged.  Now this was a custom 7 core radiator built in 1985 by now defunct Webster Radiator in NY .  It was made on 7 cores of 3/8 tube in cross flow pattern and literally didn't have 500 miles on it as I primarily showed the car off a trailer.

I had the radiator 'rodded' to clean it out and merrily proceeded to reinstall it.  Fast forward through a move to Northern IL I never proceeded with the further testing till this spring.  Pull the car off the jacks  this spring and start it up to test the cooling system and same thing happens, but much very slowly.  The engine can idle fine but as soon as I add any heat by driving it or reving it it can't dissapate the heat generated.  This time, however, the radiator was seemingly getting hot.  Take the radiator out again and over to a shop and have it flow tested.  Told it was fine and reinstalled.  Start the car and it still has water temp creep.  I decided to enlist a second pair of eyes and have a race engine builder watch the car warm up with me and a friend of his was watching and recommended using an infrared heat gun to measure the engine and radiator temp as she warms up.  As dwe do we see that the engine warms up fi ne with no apparent hot spots.  The top few inc!
 hes of 
the radiator are engine temp but as you test the lower rows of the radiator the temp drops radically.  (i.e top inlet 170 degrees and bottom of the radiator 100 degrees).  We believe that only a few rows of this monster radiator are working and that the tiny 3/8 tubing may have accelerated its clogging.  I learned that today radiator technology has changed dramatically from the eighties.  New radiators use 1 inch to one and a half inch tubing to cool with fewer rows.  

So I'm tossing this radiator TFO (the f--- out) and looking to purchase a new aluminum radiator.  So far my best choice is an aluminum Griffin radiator using NASCAR standard size of 27.5 long and 15.5 high, Ford style inlets and outlets.  Three rows 1.25 inch tubing rated for up to 600 hp.  Priced at $270.

So,  does anyone have any input on the size and shape of a aluminum radiator for a 70 AMX or other AMX radiator support of this size?  Hope the radiator technology issue of core tubing size is of value to everyone running around with a older radiator.  

Hal
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