pressurized cap on a flathead?

My aftermarket radiator came with a 9.0lb cap.can i run that with stock 24 stud water pumps?

 

The water pumps aren't normally where you'll see a problem with leakage, usually it's the head bolts/studs. I have 2 caps, one is a 7lb. for summer and the other is no pressure for the cooler months. Less pressure seems to be better with a flathead so use as little as necessary to get the job done or you may see some leaking.
Rich

 

It more depends on your radiator , the top tank is the first to let go if its the early style large top tank. As yours is aftermarket it will be fine . We run 13lb on a 36 truck radiator. Though we run new drake pumps , no leaks for the last 3000 miles.

 

7lb works fine, i run a aftermarket rad and the 7lb cap does the job

 

14lb cap with a blown flathead, runs cool on the road and is good in traffic too, although sometimes I have to turn on the fan.

The higher the lb pressure on a cap the higher the boiling point. Which really should be a good thing with a flathead! But it all depends on the radiator and cooling systems capabilities.

Conversely I run a 7lb cap on my original 55 olds radiator with 455 motor and it runs too cold, I'm struggling to get it to show 1/4 on the temp gauge that's with 1/3 radiator covered.

 

On my last couple of FH powered deuces I ran Walker radiators with 7 lb caps.