What pressure rad cap?

-

65Valiant310

Well-Known Member
Joined
Jan 18, 2006
Messages
822
Reaction score
4
65 valiant radiator- 3 core 19 inch wide...got it repaired due to a small top tank leak
The shop insisted i should use a 7lb cap since my previous cap was 14
does this sound right?
i tried out the 7lb and it cools fine just wanted alls opinion
thanks
 
hmm...i ran a 14 for years before it started leaking
and pushed the car in hot az temps-road trip and didnt skip a beat
 
The higher the psi rating, the higher the temp will go w/o boiling. But, your system has to be "up to snuff".
 
65 valiant radiator- 3 core 19 inch wide...got it repaired due to a small top tank leak
The shop insisted i should use a 7lb cap since my previous cap was 14
does this sound right?
i tried out the 7lb and it cools fine just wanted alls opinion
thanks
I think 13 was standard. Ditto the 7lb bandaid for bad rad.
 
That is interesting, as ive been reading a lot about how 50s to mid 60s radiators were built to use a 7lb cap,
The higher rated caps affect gaskets/plugs on ur engine as well...not just the radiator!
 
Many of the chevys used 7lb caps, I would ventrue to guess that your radiator guy might be a brand x guy.

Or he was not sure if his fix would last under greater pressure, although I'm sure he did what he was supposed to do.

I run a 13 lb cap, but my radiator is brand new.
 
That is interesting, as ive been reading a lot about how 50s to mid 60s radiators were built to use a 7lb cap,
The higher rated caps affect gaskets/plugs on ur engine as well...not just the radiator!
Was running a 7 lb before our recore. Switched caps with our other dart for 13. Now running 13 on new core and 7 on rad with small leak.
There are several schools of thought on the issue of more pressure = cooler running temps, etc.. You can run either but the 7lb will relieve pressure alot sooner than 13, so...... Use em how you need em!
Main thing though is to be sure you run a cap for an overflow system if you have an overflow bottle. Otherwise you will have hose collapse, overheat issues etc...
10-4!
 
Higher psi cap will raise the boiling point of your coolant. If it isn't boiling the coolant with the 7 psi cap on it then leave it. If it is then raise the pressure of the cap. I run a 16 psi cap. Pretty sure that's what it came with.
 
65Valiant310. All my research on radiator caps tells me higher pressure does
not help run cooler. It just raises the boiling point approx 3 deg. per pound.
i.e. 10 lb cap = 30 deg. rise = 212+30 = approx 242 deg. to boil. My 51 Nash
street rod never has run hot and I have a 4 lb. cap. My 65 Valiant with a
built 360 runs a 13 lb. cap as per the spec. for the truck rad. in it.
 
-
Back
Top