I have 502 x whipples and stainless marine exhaust x CMI switchable tips.

Question is should I have flappers inside the pipe somewhere? They are straight pipes and if I look up them when the tip is open I can see all the way up to the bend by the riser. I am concerned about reversion or when just plain stopping having water ruch up there. What should I do I cannot put flappers on the outside as it would interfere with the tips.

I would contact Teagues they may have an internal flapper that can be installed.

The cheapest way to go is to put them at the end of your tips, about 40 bucks

No reason to question wether or not you need backflow flappers. The cost of a hydrolocked engine is virtual destruction compared to the cost of the insurance (not fool-proof) flappers.

As an alternative I would also check CMI for the new internal to the pipe tip duckbill flappers that they made up for Mercury on their new 525HP engine released in Miami. Call CMI in Wisconsin and ask for Tom Beson. He'll know what you are asking about. They fit in and you don't even know they are there.

Mark

Funny....I just saw Teaque talking about those last night on Speed channel!!! Yes he sells them !!!

Does anyone know if someone makes an external flapper for angle cut tips ?

Our Checkmate was designed not to require flappers. One of the first things I noticed about the boat before we bought it was that it did not have any flappers. I did some research and talked to the fatory and found out that the factory installed spacers between the risers and the exhaust manifold which resulted in a greater slope from the tips to the motor. The factory said that they saw no need for flappers and they have never heard of any reversion problems with this setup. The boat is 14 years old and has not had any problems yet. If you do get flappers, don't get the rubber ones. Depending on how much hp you have, you may keep blowing them out. You can send your tips to the manufacturer and have stainless ones welded in. However, the stainless ones sometimes rattle at lower rpm's.

Before the question if flappers are needed, We need to know where the water is injected into the pipe? right after the header? or is the pipe dry?

Unless you are running dry headers the rubber external flappers work well and don't burn off. I run my headers almost dry. I burn up internal flappers almost instantly but it doesn't damsge the external type.