One reason there is so much confusion about these two valves, is that most all the vendors don't know what they are..
...and call them the wrong thing.
The round valve is a hold off valve. Holds off the front brakes untill around 40 PSI (I think
) so car will not nose dive.
The other valve of the fram rail is a press reg valve.
John Z posted some good info some time ago on the correct nomenclature and function on the 69 Brake valves. Later I will search for it . It seems the CRG message board is down right now.
Mike
