[DeTomaso] Capacity of overflow tank

[JDeRyke at aol.com]

In a message dated 5/2/13 7:32:47 AM, demongusta at me.com writes:

> You might want to pressure test the Hall cap   - the only reason I 
> mention it is because it is supposed to be 16 lbs. - mine was 9. So I went to the 
> old Stant standby. Been playing around with 16, 18, and 21 - 25 lb. caps. 
> What's the downside of a cap with too much pressure, other than raising the 
> boiling point?
> 
Most non-custom-built radiators simply won't take pressures above 20 psi 
without ballooning or swelling the tubes, which cuts air flow   & destroys the 
cooling. NASCAR uses custom welded rads that can (usually) take 30 psi but 
that's not what you see for sale in the catalogues. Check to see what your 
rad was pressure-checked at by the mfgr, then subtract 10% for ageing unless 
it was new this year. 
And the pressure rating of a rad cap is very dependent on the height of the 
surge tank neck; original Euro- necks are taller for use with Euro caps, 
giving less compression on shorter U.S. cap springs- thus they hold lower 
pressures than rated. You can double up on the rubber gasket thickness to gain 
some pressure back, but usually its better to simply replace the tank neck. 
The bottoms of stock tank necks are often rough, causing pressure leaks & 
further decreasing the sealing & pressures it will hold. FWIW- J Deryke