I have a stock 7.4MPI and I have taken the exhaust through the hull. I have experienced a hydraulic lock and I would like to either get higher risers or place a spacing block between the risers and the exhaust manifolds. Anyone have experience with this modification?

I would not recommend playing around with the stock Merc. exhaust. The system is just not worth spending money on. You have to bite the bullet and go for aftermarket exhaust. It will be money well spent. You wont be sorry.

How is a stock 7.4 suffering from reversion? I thought you had to have a hot cam and/or big HP to invoke reversion...

???

D. Ocean
Pompano Beach, FLA

From what I have been told the spacers under the risers just open the door up for more possible leaks...because of the additional use of more gaskets.....Fred

He didn't say it was a reversion problem.
Baronbob, what happened? Was it reversion, or did water back up through the pipes when you throttled back? Or something else? You did a through hull conversion? Did you put flappers on the pipes?
The problem will determine what the soloution needs to be.

Do a Stainless Marine Hi-Torque system w/ built in 3 inch risers( 3 inches taller than stock). You'll have no more leaky riser gaskets,take alot of weight out of the back of the boat and add a little power to the motor.

When I did my conversion to thru-hull I went with Stainless Marine and had them custom make the risers. The standard risers caused the exhaust to exit right into my swim platform. Also I was a little worried about reversion so I had a set made 6 inches taller. They worked great.....Talk to Brownie at Stainless and he can set you up.
BH