what is reversion ?

[jimmmyb]

is reversion when you have basset water injected headers, and you leave water on at idle. i don't know what reversion is
jimmy b

[Jungle Boy]

The best I can do for an explaination is, when your pump is taking in so much water that the nozzle/pump can not expell it fast enough, so it is coming back out the intake grate. This will cause vibration thru the drive train. The vibration can be bad enough to break the ring gear, crank or harmonic balancer. If you have reversion, you should close in the back of your grate about 1/4" inch at a time until it is solved. The grate I deal with a steal for aluminum jet boats and are fairly easy to modify. Lake boats are unknown to me, but it should follow the same principal.

[Rat Raft]

I think the type of reversion Jimmy was asking about is exhaust reversion. When the exhaust valve is closing the intake valve is already opening. The longer the duration and closer the centerline the cam has, the more time both valves are open at the same time. At low rpm some exhaust is sucked back into the cylinder. This is what gives performance cams their distintive lope. Of course if you have water in the headers some of this is also going into the cylinder. Some of it excapes past the rings and causes water in the oil. As the rpm comes up there is less time for all of this to happen and the exhaust gases are being pushed out at a much higher speed. This causes a vacumn effect in the cylinder and helps pull the intake charge in. The bigger the cam the higher the rpm this happens.
This is a simpflied verson of what goes on but I hope it helpes

[riodog]

JimmyB, when Mr. Basset (sr)came up with his "T" valve for the water injected headers it worked great if the cam timing had very little "overlap", i.e., the intake valve and the exhaust valve were not open at the same time for very long, (we're talking same cylinder). With camshafts with a lot of overlap(for higher rpm applications), with the intake valve open AND the exhaust valve open, AND the piston on the downward stroke it creats a vacuum in the cylinder and can suck water back into the cylinder that normally would be blown out the back of the headers. This occurs at low (1500) rpm when there's not enough exhaust from the rest of the cylinders to keep the water going out the exhaust. That is why most FKB (fairly knowledgable boaters), remove the ball and spring from the inside of the "T" valve and utilize a manual "watervalve" to control the flow of water to the headers. Coming off "plane", or when bringing rpm's down around 1800-1500 the water valve is turned off to prevent this occurance.
But then again, I never claimed to know anything so I don't if I'd believe me or not.
the dog

[Hallett of a Dream]

Rio???
On this valve (Gate Valve) which I have, are you saying that everytime you slow down or stop, you need to reach back there and turn it off to keep water from entering?

[Oldsquirt]

Hallett, the answer to your question is NO! When this mod is made, a new valve is added between engine and "T" valve for headers.The new valve is located by driver's seat. Lines are run up to the driver's seat and back to the "T". It allows manual control of header water only.

[flat broke]

If you want to be really slick, You could hook up a MSD RPM switch to activate/deactivate a solenoid feeding the injection lines. I set a mock system up for a buddy of mine's boat, testing it with my chevelle, and a garden hose and it worked great. I would also install a dead mans valve (1/4 turn unit) right in front of the solenoid in case of a system failure so you would still have control of the injection flow. I can give you part numbers etc if you are interested.
Chris

[ponponracing]

To understand reversion, you have to know camshaft overlap. Overlap is the period of time during wich intake and exhaust valves are opened at the same time. The reason of that is that the column of burned gas going out at high rpm is so effective that it help sucking new gas in cylinders when exhaust and intake valves are opened.
But at idle or at low rpm, that column doesn't exist and exhaust and intake valves are still opened at the same time. So, instead of exhaust gas column sucking new gas by the opened intake valve, it's rather exhaust gas that are sucked back in cylinders when piston goes down during suction stroke. That's why big cam engines are so shaky at idle speed: burnt gas come back in cylinders.
This is called reversion. The problem with a boat motor is that exhaust gas are mixed with water when they are sucked back in the engine.
And motors don't like water in cylinders.

[Hallett of a Dream]

Please post those part numbers, or email them to me. My gate valve and hoses are all set up in the engine area, I guess I could extend them into the drivers area, but what about leaks or too much pressure blowing a line? How much pressure should be going to the injectors? I could set one valve in back to reduce pressure and then another in the drivers space to stop the flow.

[wrightnow]

There are many ways of dong this and most work well, so this is just another way of controlling the water to the headers.
From the thermostat housing I run one line to the basset check valve and then to the headers (leaving the ball and spring in). The other line from the thermostat goes to a valve and then out the boat. This valve will control how much pressure is sent to the headers. The more the valve is open the less water will be sent to the headers. I run the boat at about 2800RPM and then adjust the valve so water just start to come out the header.
This works for me since I don?t want to bother with the valve, set it once and leave it alone.