Have a 496 Mag that has a stock Mercruiser flame arrestor on it. It has a lot of, what appers to be, salt and sand in it. I have gone through 2 bottles of carb cleaner and numerous blasts of compressed air. However what is in there wants to stay. So the question is, should I just replace with the factory flame arrestor or should I go with a K & N setup? Is there another filter/arrestor I should consider? The motor is bone stock.

The stock is very robust. The stock has far better performance than the K&N. I tested both and the stock was 1-2 mph faster.

I replaced the stock with the K&N filter; I saw the opposite with a 2mph gain. It looks better as well.

We've tested K&N air filters on stock and built up 496's and we've never seen any improvement in power levels and in a few cases a little less power. The stock flame arrestor has a bell shaped interior mouth and I think that makes for better air flow. It's not a filter though just a flame arrestor so if you are running in a dirty enviroment or such a K&N could help with dirt control a little better than the stock arrestor. My call is save your money and spend it on things that work better.

Best Regards,
Ray @ Raylar

The stock Flame arrestor has salt and sand caked in deep. I spent 2 cans of carb cleaner on it and still areas of blockage. The reason I had asked the question is the K & N set up is a fraction of what a new Flame arrestor is...

Check eBay they are about $15 for used OEM flam arrestors in good condition.

I Run Kn On The Dyno They Work Good . There Was No Lost In Hp Over Stock . Who Wants Sand In There Motor??????not Meare You Raceing Your Boat????if Not Go With The K/n It Is A Better Filter In My Opion

Just take hot water and Joy dish soap and soak it. It should come clean the screen in it is stainless so the salt shouldn't be corroding it.

I have been soaking it for over 24 hrs now. Taking it out twice and blowing it out with 100psi compressed air. It has gotten a little cleaner, but there is still quite a bit of salt in there. I will continue to soak it and spray it out twice a day.

On another note, I have run the boat with the K&N and have run it without anything at all. So far the results are the same, so the K&N may show slight HP drop on a dyno, I'd say real world conditions there is really no adverse effects. I would still prefer to have the stock flame arrestor on as the Wayne County Sherrifs will try and use anything for a reason to issue a citation. Even though the K&N is "marrine approved" a Sherrif would most likely give me a ticket (if I get pulled over) and then to fight it in court would be a pain in the ass.........

Where the hell did all that salt come from???
If you've got that much salt water in your engine compartment and the bilge so the belt is tossing it up to the flame arrestor, the flame arrestor is a minor problem versus the corrosion from salt and the damage the salt water getting ingested into the engine is going to do!
Whats the real culprit here?

Best Regards,
Ray @ Raylar