Radiator cap pressure?

[Stumper]

What is the correct radiator cap pressure for a 62 big block without A/C? I have seen some say 16 psi for all and others say 13psi without a/c?
What is the downside to running a 13psi cap?

 

[diesel_lv]

The lower the psi, the lower the boiling point. That said, some older cars, not the engines, cannot hold 16psi in the heater core. I tested my system on my '67 and had no problem w 16psi so that is what I run.

 

[Michael_]

Mine also says 16 psi.
1969 dodge charger r/t 440hp with a/c that is.

 

[casey henson]

I tend to air on the light side on anything that is old anymore. For me I like to run 7psi and coolant recovery bottles. not just overflow catch cans. I have never really used a high pressure to raise the boiling point. I run 160 or 180 stats or sometimes no stat at all with a restrictor washer in place of the thermostat. On my 400 right now I am running a 7psi cap,180 thermostat and recovery bottle.

 

[Ranger16]

The difference between a 13 and a 16 PSI cap is simply the max pressure at which the cap will vent. Either one is probably below the actual operating pressure.

Likewise, the boiling point of either is also well below your cars actual running temperature. The difference between the two at 50% coolant/water is less than 10°.

I'm pretty sure all radiators as well as heater cores are tested at well above these pressures.

All that said, I'd opt for the 16 psi cap.

 

[Cranky]

I'm the same way.....run the lowest cap pressure possible. Higher pressures stress hoses, heater core and radiator. Many have called me stooopid for that but after 35+ years of doing that, it's been proven I'm not stooopid. If you have a good radiator and it cools your engine, there's no reason to run high pressure caps.

 

[MoparLeo]

And have the cap and the cooling system pressure checked. New doesn't always mean it is good..

 

[Stumper]

my radiator is a 68’ 22” and works fine. I’ve been running a 16’ cap but get some seeping at heater hose and freeze plugs. Been thinking of trying a 13 lb to see the impact on the wet spots - and cooling.

 

[PlymCrazy]

Of all the vehicles my dad had growing up from early 50’s to late 70’s Mopars, Fords, GMs he had, I’m estimating he had close to 40 different cars and trucks. One of my chores was to check the fluids in the cars when they came home daily. From straight 6’s to V6’s, SB to BB I only ever saw (1) or (2) caps that were 7psi installed. Most commonly I saw 13, 15 or 16 psi radiator caps on the rest.