Re: 60-66 Radiator Over flow tank
 

Does anyone know if there is a certain cap that needs to be used on our radiators when an overflow reservoir is installed? I have a 13# cap with a lever on it (to release pressure it think). Im wondering if the pressure is too high for my cooling system?

I have a 4 core copper Harrison with the Ford overflow / wiper fluid combo (like '64 Shortbox). Seems that the coolant in the radiator disappears yet there will still be coolant left in the reservoir. Its as if the cap doesn't let the cooling system pull the coolant back into the radiator when everything cools off.

Never seems to run hot. 190 consistently. Can get 210 when towing and over 100* ambient but never boils. Running a 19" mechanical fan with the heavy duty Hayden clutch.

Re: 60-66 Radiator Over flow tank
 

Yes the cap needs a gasket around the perimeter of the cap. Look #33 on the diagram above from Rocknrod. Any cap from whatever year they started installing overflow tanks on up will work.

Re: 60-66 Radiator Over flow tank
 

Got it. Thanks Yankee. Ill try and get a lower pressure cap (less than 13# anyway) and one with an upper gasket around the top of the filler.

Re: 60-66 Radiator Over flow tank
 

I don't think you will find a modern cap with the gasket and a 13lb rating. I would go to a 16lb anyway. It will help keep the coolant in the radiator instead of easily overflowing into the reservoir. It won't hurt the system.

I used to use a 20lb cap in my SBC Chevy for circle track racing. We couldn't use antifreeze so a high pressure cap was the only way to keep it from puking.