Motor Height

[jacklake2003]

Regarding motor height.... I'm getting ready to mount my Mercury 850 (manual trim, [20" shaft]) on my Viper. Is there a good rule of thumb for height? I'm thinking about the anti-cav plate about an inch above the bottom of the pad. Sound OK? It won't have a jack plate either, so I'll use a hardwood block to raise the motor up on the transom (if needed) and then bolt the motor to the transom. I know I'm not exactly creating a high-speed Viper here, but it's what I have. What do you all think?

[buddhaboy]

do you have a low water pick up? you can pick up a 5 inch set back jackplate for about 150$ is well worth it

[jacklake2003]

No, I don't have a LWP. However, I did consider getting a jackplate to make any adjustments/future engine changes easier. I'm just trying not to spend a whole lot of money on this project. It may be worth $150 though.

[buddhaboy]

well worth it. one inch above sounds good with your set up, but trials will be the only way to tell . what prop are you planning on running?

[jacklake2003]

Well, currently I have probably the worst possible prop for it. It's a factory 3 blade (can't remember the pitch, but WAY to small). My parents had it on a bowrider in the 90s and it had an amazing hole shot! Not really sure what I'm going to use. I guess I'll start with it and try different ones from there. I think I rememeber reading that the 850's (it's a mid/late 70s) had a lower gear then most which makes my small prop even worse!

[hydrostream76]

do you have a water pressure gauge ?
i would recommend u get one if you want to raise it high or you may cook your motor

[buddhaboy]

I was using a small hub prop on my 150 johnson and it was horrible!!!!! Bad cavition and blow out . changed it up and it was a different boat. the motor your putting on, what hp? With out a jake plate and at least a five inch set back i would set your motor to its highest setting and work your way down, but it could be good. before i changed my motor up i was running a yamaha 115 v4 without a jackplate and setback mounted to the transom and i ran on the hightest setting and the boat felt great just could not get more than 65 mph . you should for sure invest in a 24-26 pitch prop to start out maybe a 19 if your pulling anyone. good luck let me know what happens . Jason

[jacklake2003]

Jason it's just an 85hp, so I don't expect too much. Not only that, there is no vertical adjustment on the motor. That being said, based on comments here and thinking about it more, I ordered a manual jackplate yesterday. It wasn't much money and I think it will be well worth the investment. Thanks all,
Chris

[buddhaboy]

nice now you just need a good prop. is it a 20 or 25 inch shaft?

[jacklake2003]

It's a 20"