I have a bronze scoop intake for my wash down pump. When installing do I need to use bronze screws or are stainless ok? I hate to buy a box since I only need four...
It is usually not a good idea to mix dissimilar metals in water. Saltwater is worse than fresh water since saltwater is more electrically conductive.
How bad an idea depends on how far apart the metals are on the galvanic series and how long they will be immersed in water.
If they are seldom in an electrolyte (water) it hardly matters.
If in water, especially salt water, then the metals' relative position on the galvanic series indicates the potential for corrosion of the metal that is lower in the series.
Here is a link to the galvanic series https://en.m.wikipedia.org/wiki/Galvanic_series#Galvanic_series_.28most_noble_at_top.29
Notice that stainless steels are at the top of useful metals. It is not a good idea to connect stainless to other metals.
Stainless and silicon bronze tend to play nice together.
Look how low aluminum is. Why do outboard manufacturers connect stainless steel to cast aluminum? Me thinks it is planned obsolescence.
You learn something useless everyday.