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Tinkerer 01-17-2002 07:59 PM

silent choice flappers
I have Lightning silent choice headers that I run almost dry. Every year I lose about 2 of the SS silent choice valve flappers. They break in half and blow out. Has anyone else had this problem. When this happens all the cooling water for the exhaust goes to the side without the flapper because of less backpressure this in turn burns up the connector hose. So I want to solve this problem.

formula31 01-17-2002 09:35 PM

Totally confused about your question. Most all diverters have a stainless steel diverter plate. Are you burning this? Or are you taking about the backflo preventers in the tips or outside like the salisburg flappers? If you are breaking the ss valve plates in half, it is probably due to your cam creating a reverse pulse at idle that is opening and closing the plate with each cycle. Im am not familiar with Lightnings setup. The air cylinder or solenoid has to hold the plate open.

Tinkerer 01-17-2002 09:42 PM

They are the diverter SS plates that are breaking in half and they dont move at idle when they are closed or open. I think it might be the big cam though.

formula31 01-17-2002 10:03 PM

If the plate are bouncing they will break, I built my own and the plates are thick but I still used an overcam spring to hold them either open or closed. I can send you a pic when I get hoem of what I did.

Tinkerer 01-17-2002 10:45 PM

I run my boat with the exhaust closed mostly. I am using the pnematic cylinders that don't allow the plates to move when they are closed.

formula31 01-18-2002 10:16 AM

That might be the answer. I dont think the silent choice was intended to be used a lot above idle. Could be wrong on that but thats what I seem to remember.

bobl 01-18-2002 10:40 AM

I think the problem is the flappers are getting too hot. You must have sufficient water to cool them or they will break.

Advantage_Rob 01-18-2002 10:57 AM

I lose lots of them too always have since day one on stock 502efi's w/silent choiceI wheck them pretty often and you can feel them and they stary to get hard and deform, then soon they are gone, There purpose is to stop water from going up into the exhaust and hydro locking your motor while stopped with the motors off in rough water conditions.

formula31 01-18-2002 03:23 PM

ROB, I think he was referring to the stainless diverter valves, not the rubber backflow flappers.

Mike Shaak 01-20-2002 09:01 AM

:eek: Silent chioce is not to be used above 3,000rpm's

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