View Full Version : can internal flappers be added to original exhaust

02-02-2011, 12:46 PM
I have the old 1966 interceptor manifolds with straight exhaust through the transom on my Ski Sporter. It sounds so nice with that 289 in there, but I am always worried about water getting sucked back into the engine. When I slow down from planing, I always "bump" the throttle up a bit to stay in front of the water surge behind the boat. When launching or docked, I always wedge some silly toy rubber balls in the openings, but I would like to install some type of real flapper internal to the original exhaust set up.

I have tried to clamp some rubber flappers on the outside and as the motor came up to more than an idle leaving the dock, they both blew off and sank.

Is there a flapper that can be slipped inside or a way to modify my existing setup? I would like to keep the original exhaust trim rings for the right look. And another followup question is will it change the sound of the exhaust much?

02-02-2011, 12:59 PM
I had these tack welded inside my exhaust tips - http://www.eddiemarine.com/store/cart.php?m=product_detail&p=11431&c=59

They rattle a little a idle speeds but otherwise I am happy with them - I don't remember paying that much though, but its been several years

02-02-2011, 04:46 PM
There are exhaust pipe through hull flanges that are designed to accept the hose clamped rubber flappers. The flange has a raized LIP or Ridge, around the end of the exhaust that prevents the flapper from blowing off once it's clamped on. :) DJ

02-03-2011, 08:39 AM
Sometimes you can put an internal flap in. It will depend on how much space you have inside the run and where you put it. There are also some that are already in a ss tube that you would just slide into your exhaust hose between the tip & the riser, however I dont believe you will have the room for that one, and I also think your diameter is likely to be smaller than the normal sizes they are offered in. Worst case you could replace the tips to a new stainless tip with a flapper already in it if adding one to your existing set up is too much grief or not possible.. ;) Jamie / Lakeside

02-03-2011, 11:49 AM
just go back the the rubber flappers..when you install them use laquare thinner and wipe the outside of the tip and the inside of the rubber flapper..then take a thin coat of 5200 and glue them on then clamp them just uptil you see the rubber start to squeeze wipe off the access 5200 and let them set up..the only way they will come off is to cut them off..

Bobby D
02-03-2011, 12:09 PM
+1 on rubber flappers never had any problems with them.

02-03-2011, 12:51 PM
Has anyone tried these...

02-04-2011, 08:25 AM
Has anyone tried these...

Yep, thats similar to the kind you would put in the exhaust hose. The problem is those are only compatible with certain 4" tips..

My thought is he will likely have to either replace the tip to a newer slightly different style, OR modify the one he has, Or like fixall mentioned in essence glue it to the tip before clamping using 5200.. :) Jamie / Lakeide

02-04-2011, 11:00 AM
Thanks guys...it's not number one on my list of things to do (so many things on the list), but all the ideas help. At some point I will use one of these options or just fabricate my own for the smaller diameter.

02-13-2011, 01:08 PM
I am from the school of if it isnt broke dont fix it. I have had my 16 with the interceptor power since the early 80s with no flappers and have never had water in the exhaust through the tips. I know your family has had yours have since it was new in 66 with no flappers. I feel there is no need to have them to prevent inversion with the interceptor manifolds. I think the external flappers will take away from the original look also. Just my opinion, but also a different opinion from what you have got so far.

02-13-2011, 01:16 PM
Good point...:)

Being in QA, I have a problem with trying to anticipate every potential issue or problem and want to pre-solve it. Maybe I should stick to the basic issues before I worry about this one.

My dad used to say..."that is a great solution to a problem that isn't there"