Our new-to-us DeFever 49 RPH

[SteveK]

Are the antisiphons mounted at sea level or higher?
what backflow prevention does the exhaust have?

 

[KnotYet]

Are the antisiphons mounted at sea level or higher?
what backflow prevention does the exhaust have?

For the last 40 years the anti-siphon valves have been about 2-3 ft above sea level.
This boat has travelled from here to Alaska and down to southern Mexico on these engines.
Based on that, it would seem that exhaust backflow hasn't been an issue for this installation.