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silent choice and power

Old 09-07-2017, 02:59 PM
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Default silent choice and power

Just picked up an older Fountain 27 single with no engine, looking to build a cruiser any suggestions, I have a mercury silent choice and a 502 and a 540 both have 9.5 compresion.Would like to use the silent choice. Is this possible,? of course i would like to go as fast as possible. Suggestions on cam and exhaust
thanks
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Old 09-07-2017, 06:53 PM
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You can run either engine through silent choice, BUT you are limited by the exhaust to a fairly conservative cam grind. Water has to be mixed with the exhaust flow before the silent choice diverters. That limits the length of dry exhaust length. The closer to the valve the water hits exhaust gas, the less cam overlap you can run because of reversion. A 27 Fountain is a very respectable boat. You did say you want a cruiser. As opposed to wanting to maximize top speed. You can't have both. I assume you already have a Spousal unit and she gets some input into the finished product. When the exhaust is too loud I find I get fingernail marks in my arm since I can't hear her yelling SLOW DOWN!!!
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Old 09-08-2017, 10:46 AM
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low speed only, they were never designed to be closed under power
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Old 09-08-2017, 12:25 PM
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Originally Posted by dereknkathy
You can run either engine through silent choice, BUT you are limited by the exhaust to a fairly conservative cam grind. Water has to be mixed with the exhaust flow before the silent choice diverters. That limits the length of dry exhaust length. The closer to the valve the water hits exhaust gas, the less cam overlap you can run because of reversion. A 27 Fountain is a very respectable boat. You did say you want a cruiser. As opposed to wanting to maximize top speed. You can't have both. I assume you already have a Spousal unit and she gets some input into the finished product. When the exhaust is too loud I find I get fingernail marks in my arm since I can't hear her yelling SLOW DOWN!!!
With you here , Got fast and loud boats Cant come in and out of marinas early or late it pisses everbody off. only need quieter then.
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Old 09-08-2017, 12:44 PM
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But unfortunately the silent choice design limits the exhaust even in open mode. But stuff is what it is...
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