Good Evening.
I have a question about radiator caps.
Gilbert my 77 S3 2 1/4 petrol, has a square, flat topped radiator, with overflow bottle, which i believe is a S2 one?
What pressure cap should I be running. it has a 4 (psi ?) on it, as does another radiator I have of the same description above, fitted to 75 S3
10 for S2, 9 for S3, i have read, but would it matter the radiator type fitted ?
The reason for asking is, if i half fill the overflow bottle, it blows put to about 10/20mm first time i stop and thats where it likes to be.
wonder if cap is to low ?
Thanks


whitehillbilly