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Old 08-12-2013, 10:27 AM   #1
fomocoloco
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Default 4 pound rad cap

went to NAPA today for a 4 pound cap for my new radiator. they can't supply one. anyone have a part number? car is stock 36.
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Old 08-12-2013, 11:06 AM   #2
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Default Re: 4 pound rad cap

Ford part #48-8100 but according to the parts book pressure caps did not start until '38 part number 41A-8100. Don't know if that one would work on your '36.
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Old 08-12-2013, 11:16 AM   #3
wspiker
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Default Re: 4 pound rad cap

I got mine from Bob Drake Reproductions.
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Old 08-12-2013, 11:24 AM   #4
cmbrucew
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Default Re: 4 pound rad cap

Fomoco

I have a Napa 4# pressure cap on my 41. Part number 33017.

Bruce

Works good
Lasts long time
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Old 08-12-2013, 11:25 AM   #5
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Default Re: 4 pound rad cap

CARQUEST #33002 worked on my '50.
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Old 08-12-2013, 11:49 AM   #6
37 Coupe
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Default Re: 4 pound rad cap

None of the above 4 lb caps are going to work if you don't have the radiator or the overflow in the neck to hold the pressure. I am not sure about the 36 passenger car radiator . The 4 lb cap works on my 37 Ford but mayby because my radiator is the later 38-39 standard 81A replacement,I think the 39-40 Deluxe had the overflow configured that would not allow a 4 lb cap to seal. You may need to attain the pressure by installing Skips valve on the overflow tube.
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Old 08-12-2013, 12:58 PM   #7
fomocoloco
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Default Re: 4 pound rad cap

Quote:
Originally Posted by 37 Coupe View Post
None of the above 4 lb caps are going to work if you don't have the radiator or the overflow in the neck to hold the pressure. I am not sure about the 36 passenger car radiator . The 4 lb cap works on my 37 Ford but mayby because my radiator is the later 38-39 standard 81A replacement,I think the 39-40 Deluxe had the overflow configured that would not allow a 4 lb cap to seal. You may need to attain the pressure by installing Skips valve on the overflow tube.
i'm using skip's 3lb valve and 7lb cap. working so far.
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Old 08-12-2013, 03:15 PM   #8
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Default Re: 4 pound rad cap

As far as I know my radiator is stock.When I had it rodded out, the radiator guy said that it has an overflow tube and he was pointing to the tube that runs down the front.He said any old cap will do.Even a gas cap(you could get one of those tonight).Mine is not a pressurized system so a pressure cap is not necessary.Yours may be the same.
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Old 08-12-2013, 04:25 PM   #9
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Default Re: 4 pound rad cap

A stock '36 Ford radiator is not pressurized, and will buckle if a pressure cap is used unless it has been modified internally by soldering on an angle brace on the underside of the large area at the top of the top tank. Those who do have a pressure cap without such a brace will notice an oil-canning effect under heat/cool cycles which will, over time, break the solder joints that hold the top tank together. 4 pounds woulnd be the maximum for this tank in any case, and for any tank of the same era.

To fomoloco and others who run skip's 3 lb valve, no matter what cap is used in conjunction with this valve, the pressre is limited by the lower pressure valve. This is, of course, if the overflow tube is not within the fill neck, which would then be controlled by the higher pressure cap.
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