Can anyone share the procedure for changing the angle on the adjustable Stellings extension boxes? Mine are factory original on boat from 1999 and I"m looking to raise my drives. Thanks.

It could be pretty much a major re-rig depending on how much you want to change the drive height. When you move the box much (more than 1") you may/could/will likely have the drive shaft at too much an angle. Others may have suggestions on the max angle. If the angle is more than a few degrees, you would/may have change the engine heights or move the current the engine mount positions to get the appropriate drive shaft angle. If you change the engine mount positions, in almost all cases you are likely going to have rework your tail pipe configurations, hoses, etc. IMO, the best solution may be to switch to the IMCO -2 lowers and leave the boxes where they are.

Thanks for the info. I've never had them apart but was hopimg there was a ujoint and we could just move the box to the next hole. If it requires changing engine height, couplers, etc its really not practical for me to adjust.

It really depends on what hole they are installed with now. They have 3 holes.
You also have to watch the shaft/ujoint angle if you raise it.

You say you've never had them apart???? You are supposed to grease the zerts every 25-50hrs.
You can see which hole they mounted on by taking the side covers off.

Ive only put about 50 hours on it the last 3 years since we had the motors out. I think my emgine guy greased them when we pulled the motors back then. Is top hole neutral middle hole -1 and bottom -2? What I'm trying to understand is if everything from the boxes back has to come off to change to the next hole or if it can be done with drives on. Thanks

Joe,
Based on my experience raising our Stellings boxes, for each 1" you raise your prop shaft height you can expect about an additional + 2 MPH. This project can be a lot of work for a small gain. Maybe you should consider doing what most boaters do....just lie about your top speed ��

Did I say 82? I meant 92 Lol...
But seriously, I'd really like to get some air under the hull I think the boxes may be hurting rather than helping at this point if they are in the neutral position. I will be pulling the plates to check next week when I get some free time.

The boxes in the stock location help on a 353. They add about 2mph over a 353 w/o boxes.
A friend of mine had a 353 with 500's and Stellings boxes and it ran a solid 82mph.
Raising the boxes will give less response to trim due to less leverage. 353's run pretty flat, but they are supposed to with the stepped hull.

IMO, it is not worth the experiment to raise them, even if you can.

Thanks for your advise. If it's going to be a major project with questionable returns you are probably right. I keep hearing Formula raised the X at some point in early 2000's. It sounds like they were also supposed to raise the X on all boats with boxes to compensate but I'm not sure if they did for 99 models (my boat was built in 98). How would I tell?

Joe,
Just measure how far the center of your prop-shafts today below the bottom of the boat. This will allow us to give you an idea what you can likely achieve in increased speed and still allow you get on plane with 3-4 people on the boat. If you want to have 6 people onboard with some beverages, you would likely be better off staying where you are.