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Where can I find a small 7 lb radiator cap?

3K views 4 replies 4 participants last post by  trees 
#1 ·
I'm working on a 1936 Chevy truck. I have a 327 small block in it.
I gave a radiator shop and had a high efficient core. In order to keep the original grill look and use the original cap they blocked off the filler and installed a smaller cap in the back where the hood would hide it. The lowest pressure cap I can find is 13 lbs, which caused the tanks to expand and crack. The question is where can I find a small 7 lb radiator cap that will work with a recovery tank?
 
#4 ·
If you're talking about the smaller metric size cap, I ran into a
similiar problem in finding one in a lower pressure.
They just aren't available; smallest I found was 13#.

I finally cut off about 3/4 of the bottom spring coil, using
needle nose pliers and a small Dremel cut-off wheel.
This lowered the spring pressure approximately by half,
which I figured gave about 5-7 lbs for the modified cap.
(I compared it by 'feel' to a 7 lb large cap I already had.)

Works fine.... :thumbup:
 
#5 ·
I found one at a NAPA store several years ago. I used it on an original 36 PU radiator that had been modified with a filler neck in the top tank that would receive a pressure cap. Interestingly, the cap was from a Western Star over the road tractor. Some of the small town NAPA store persons know how to find things without the computer!!!

Trees
 
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