Griffin radiator is 10 min’s from my front door. I wanted my radiator custom built here in the USA but had a horrible experience with Griffin. I knew of Ron Davis radiators built quality so I called with some questions, they said that they would get back to me with a quote and answers. The following day late Ron Davis called with their quote and answers, one was the standard bung size 5/8” 18.
However, I already knew the answer, because the day before I was chatting with a friend who was running a Serck Motorsport radiator in his Bugeye. I told him about my experience with Griffin, his answer was go to the mother land and get something that will fit perfect. Early the following morning I was on the phone to the UK speaking with Roy at Serck Motorsport
https://www.serckservicesmotorsport.co.uk/p0/austin-healey/187508.htm who is the sales and production manger.
The same questions were poise to Roy and a very quick response “Oh” that’s easy it’s ½” BSP. I knew right then who was going to build my radiator; they gave me an exact quote with precise answers. What was so impressive was everyone here in the USA wanted payment up front, Roy said they only take payment after customer was satisfied.
The Whitworth 55° angle remains commonly used today worldwide in form of the 15
British standard pipe threads , which are commonly used in water supply, cooling, pneumatics, and hydraulic systems.