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TR2/3/3A TR-3A radiator cap

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M

midnight

Senior Member
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I just installed a wizar aluminum radiator - the well for the radiator cap is 3/4" deep Vs the stock radiator at 1" - what effect will result by running the 1" cap on the 3/4" well - the static spring load is 25% greater - me concern is the heater core - I have ran a 7# cap on my rebuilt stock radiator with out any problems - note, I did rebuild the heater core - midnight
 
FWIW one of our local club members tried that accidentally. His heater was fine, but the upper radiator hose blew up like a balloon and then popped. Twice.

I don't know why, but I'm guessing the cap was holding a lot more than just 25% more pressure. Maybe the spring reached coil bind, or the cap just didn't have enough travel.
 
You can get four or seven pound caps in 3/4" reach without a problem. You local FLAPS should have them for less then ten bucks.
 
Thanks - I was concerned when Wizard Radiator told me there was no problem - I will find a cap for a 3/4" well - thanks - midnight
 
martx-5 said:
You can get four or seven pound caps in 3/4" reach without a problem. You local FLAPS should have them for less then ten bucks.
Click to expand...

I'm not so sure. Besides needing 4 lb pressure and 3/4" depth, the ID of the neck for the Wizard rad measures 1/75", and this is oddball. Most domestic rad caps measure 2 3/16". I had to order mine from Wizard at $20.00.
 
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