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Random Quote: In theory, practice and theory are the same, but in practice they are diffrent. (Larry McVoy)
My boat has twin Crusader Carbed 454's. Would it be beneficial to seafoam the engines? Wasn't sure if it was neccasary for the big blocks?...and what would the steps be to decarb them if you think I should?
Some new cars that don't use a tier1 fuel develop deposits on the valves and combustion chamber. They do require some intensive cleaning. Boat engines, which run under more load, seem to run cleaner. 2 strokes tend to get deposits from the oil, which is usually not an issue on 4 strokes.
The best and easiest way to decarb your BB's is to use water. Remove you flame arrestors, fire up the engines and get them up to temp. Fill a spray bottle with water. Spray and nice steady mist of water into the carbs with the engine running. You may have to bump up the idle a little. The water will do an amazing job of cleaning your combustion chambers, valve stems, exhaust, etc. You can spray a pretty good amount....it wont hurt anything. I have heard different theories of how it works but the two most often discussed are that the water cool shatters the hot carbon. The other involves a chemical reaction. I have done this on several high performance boat engines and a couple high performance motorcycle engines. The amount of carbon that will come out the exhaust is amazing. Leave the engine run for awhile when your done to evaporate any water. I always did this prior to an oil change as well.
I know some will think this is a crazy idea. Do a little searching around the web and you will find it is a very old method used by mechanics. When an engine blows a head gasket and leaks water into the combustion chamber, you can always tell because that piston top will look like new when viewed through the spark plug hole. The only danger would be a hydro-lock condition if you literally poured water into the carb and even then it would be difficult to do. Hydro-locks occur in engines that get a cylinder full of water when they are not running and them someone tries to start it. Water injection systems are also common in high performance circles and are used to fight detonation and cool the intake charge. Those engines always look squeaky clean when torn down.
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i would try the sea foam treatment,3/4 gallon gas, can of sea foam, i did my boat and my 1941? ford 2n tractor ,what a difference, i had a valve that was sticking, (on tractor)now all better, worth the few bucks it cost, it cannot hurt, my 2 cents good luck
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I do my F351 once a season or so. Follow the directions on the can. Mine is carbed so I can dump it directly into the Holley. Smokes like a mother for a bit and then runs like a chainsaw on meth. All that smoke tells me that it's burning something out of that carb/intake system.
I also run it in my gas tank a few times a season.
In the Auto repair trade we used to use water with a little atf added for some lube and it worked good. Most people use Top Engine Cleaner, GM made the original version but there are several copies out now but they don't work as well. Follow instructions on can, we do fuel injected motors by sucking thru a vacuum hose. Boats don't have vacuum lines so you would probably be better off using the Seafoam. Still waiting to see how E-10 is going to effect carbon buildup, auto's have been having alot of problems with carbon buildup in EGR systems. Some MFR have actually been releasing bulletins suggesting certain fuel brands that lesson buildup.
Water does work for cleaning combustion chambers. Some 4 strokes build up gunk under the head of the valve which water doesn't seem to help. It's most common on engines with bad valve guides/seals that suck oil down the stem.
We used to a top end clean on our road race car. The biggest bang for the buck was cleaning the valves. Some engines can build up so much combustion chamber deposit that the piston will actually hit the head in extreme cases. This raises compression ratio, and makes pre-ignition/detonation more likely.
The water cleaning is quick, cheap, and worth the couple minutes time. Try it.
wow thanks guys! Such a wealth of knowledge! The water sounds like a good idea, and easy. So I just need to take the flame arrestor off, warm up the engine, bring it up to high idle (1000-1200 RPM) and then mist the carb intakes? Am I missing something or is it that easy?!
Take her for a run afterward to burn off any water that may get past your rings and blow out any dislodged carbon. You will be amazed what comes out the exhuast.
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