Radiator cap

[Ian NZ]

On my 1932 Ford V8 you can just about turn the radiator cap past the stop in fact there is a mark on the stop to show this has happened. It looks as if the stop has been pushed upwards sometime. I have pulled the stop down a certain amount to stop the radiator cap turning right around, what I would like to know how far should I pull the stop down to make the radiator cap connect with it It is about a 45d angle at the moment, refer to picture in mirror, of photo.

[DavidG]

It's the two slots 180 degrees apart at the top of the filler neck that determine the extent of the rotation on the cap, and not that in your photo further down into the filler neck. On early radiators the two slots were the same width such as in your photo, but in response to a tendency of some owners/dealers/gas station attendants to install the cap backwards, one of the slots was reduced in width and one the tabs on the underside of the cap was also reduced in width to prevent the caps from being installed backwards (the high point of the peaked center was intended to be at the back when the cap was in the installed position).

[G.M.]

What I think you need is a new gasket made out of the 1/8"
red rubber material from your hardware store. Drill the rivet
out and replace it with a 1/4-20 slotted round head screw, lock
washer and nut. Put a little loc-tite on the threads. This will
tighten the cap and keep it from blowing coolant out. G.M.

[Ian NZ]

I was referring to the stop under the filler neck which stops the cap from turning around and around.

[DavidG]

The slope of filler neck metal adjacent to the slots progressively restricts the tightening of the cap. There is no other stop, at least on the 30+ '32s that I've owned (of both Canadian and U.S. manufacture). If you can rotate your cap completely then either the cap gasket or the filler neck on the radiator is faulty. It also suggests that your radiator would likely leak from underneath the cap.

[Ian NZ]

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My 1932 Ford V8 has the original Canadian or radiator in it with the Early wide slots in the neck, which has been recored, and has a stop on it about 3/16 inch wide as per photo which I have made up a tool and I have bent it down as per photo to about a 45D angle so the lugs on the cap can move down the taper on the neck until it hits the stop and the cap then lines up with the hood trim. These stops are hard to see. If you can turn the radiator cap around & around by hand with the correct gasket thickness the stop must be broken off because it would be tricky to line it up with hood trim it also depends on the thickness of the gasket too because if the gasket is too thin the cap will go underneath the stop and go around.