Took my exhaust manifolds off today to replace my port engine starter and noticed some rust spots in the exhaust ports of the head. I pulled all the plugs and they are dark tan with no signs of rust. Twin 509 500 HP
Boat ran great last year. Could it be condensation on cool down or slight reversion? EMI exhaust with short ss risers and silent choice. My cam is a crane 551/534 lift 226/234 duration and a 112 LSA. I know the 112 LSA is borderline with short ss risers but that's how it was built years ago.

Thanks

its Okay, Id say condensation from sitting over the winter

...Boat is garage kept but does get down to 30 degrees at times. Thanks for your reply

How bad? This is what reversion looks like



Thats the top of the port

I would say 75% less than that...rust spots not together and no errosion

rust spots in the exhaust port almost always a result of reversion.try turning your idle speed up a little if you can.also don,t idle in gear long if you can help it.

sometimes a small amount of reversion won,t make rust,just white spots in the port.

Doubtful with the exhaust your using but I'd ck for cracks in them also as long as you have off. They all seem to be that way on that bank or just one. Also you ck other side?

I'll post some pics tomorrow..Last summer I turned down the idle to help save the cone clutch (Bravo1). I was getting a loud clunk while shifting into gear. After lowering the idle clunk sound reduced..
Fix one problem Gain another...As I said previously the plugs are perfect. 3 years ago I had a head rust out on several ports. The plugs all had rust on them sitting over night. This time no rust

An option you might consider is to the leave your idle low for shifting only and then move the RPM up when in gear.