water problem
 

I have a 1990 27ft pachange 454 and have a revertion problem only when I'm at an idle. I run a river between two lakes that takes an hour each way to get through and only suck water back into the engine when I idle in the no wake zone. My cam duration is 218 - 224 so I don't think thats the problem. I have a stock exhaust which is the two water filled mufflers on each side of the boat. I really need some help on this one ,It's getting expensive.:(

Do you have flaps on your exhaust tips? If not, get some.

Are you running an automotive cam? What's the lobe centerline?


Darrell.

water problem
 

Well Darrell, I always keep all my paper work for anything I buy for my boat in a file except this invoice I guess. I will need to look some more. I do know it is a automotive cam with a duration of 218-224.

Has the reversion always occured after the cam swap?


Darrell.

I installed the cam last year and did not have any problem,but I did not run the river last year so I was not idleing for long periods of time.

Make sure you have the rubber flaps inside the wxhaust tips at the exit.

As far as the exhaust flaps go my outlets are out of the water about 6-8 inchs when I'm moving at idle so I don't think water is getting in that way.

This took my motor out. Swapped to dry exhaust so I will never have to worry again. The new headers and pipes were a bit expesive but if I had done this before it would have been a bargain compared to the rebuild and new heads. Dry pipes are REAL loud so if you area will not allow or you don't want to deal with the noise you can put the clamp on mufflers on the back. Good luck

You should really look at the exhaust muffler installation. Is it possible that the riser outlets are equal or lower than the muffler inlets when the boat is sitting in the water? If so, water can be backing right up the exhaust hose into the riser. There is not enough exhaust pressure to push the water out of the muffler, so it just accumulates back up the hose into the riser. The riser outlets should be at least 2'+ higher than the inlet to the mufflers.

Good Luck!

How about a riser gasket, an 88 would need new ones for sure. If it is stock there should not be a problem, I had 88 454s and the riser gasket leaked and took out a cam lobe. Is the oil like milk?

The riser has a valley on top that directs the water directly over the exhaust outlet so I'm adding a two inch extension to the end of that valley so the water will flow that much further past the outlet and hopefully it will not suck the water back in the exhaust.I will also check that my riser is 2" above my out let. Thanks to all for your help