So
I've got two crusader 454 engines out of a boat that was on fire and half sunk. The oil coolers are gone presumably melted and one carby got hot enough to start melting. Dizzys, wires coolant hoses and one rad cap were also destroyed. Unbelievable the flame arrestors did not burn and look similar to a brad new units. I'm new to boats, doing the rebuilds for my brother, my question is, do flame retarders contain a filter element or are they just these thin metal slits to stop backfire and provide some filtration? I suppose boat engines don't need as much protection as automotive from dust but surely they have some filtration?
was thinking of reusing them

No real filtration.
There are built of plates or screens.

no filter element usually. Just a wire mesh or screen for spark/flame prevention purposes.

I see. Well I'll tell you they are made out of some good steel, the fins haven't even warped Nd they are thin. Probably why they want close to 400aud for a new one.
Another question,
These came with velvet drive 10-18-106 borgs the engines are lh/rh spun. Are these worth doing? I need to find a cheap crusader parts supplier because these will need all new accessories.

I will create a new thread detailing the build