Anyone repowered with a newer drive? (AQ 100 to AQ 270)

Hello. I'm a new member, currently working with one of your existing members on a resto/mod project with a 1966 Runabout 16ft. It has a B18 with an AQ 100 outdrive, soon to be replaced with a B20 and hopefully a newer AQ 270 ET. I'll provide a link to the drive identification chart I used at the bottom of this post. My question is: with the differences in size and shape of the outdrive mounting flange, exactly how much glass work is going to be required to get the flange to mount flush on the transom? I'm hoping somebody here has done this modification before and can give me some tips on making this less of a problem for us. The top of the existing flange sits perfectly into a raised radius that will surely have to be changed to adapt for the larger flange on the newer unit. I don't remember the measurements off the top of my head, but they can be obtained again if needed.

We aren't concerned with the longer, newer style steering arm or the electric tilt motor and shaft being in the way of the existing steering cable set up inside the engine compartment, that can be moved by way of adapting the cable bracket or making a new one.

The identification chart I used was here:
http://www.marinepartsexpress.com/vp_engine_finder.htm

I can get pictures if needed, but it may take a little time as the boat is at another location. Also, sorry if my terminology is skewed or just plain wrong, I don't know what everything is called yet. Also, Jim, if you are reading, I've been told you are quite the bank of 'Dyne knowledge.

Thanks,
Joe (lastRebel)

 

Hi Joe,

I don't have any experience with the Volvos. I would call the folks at Marine Parts Express. (The web site you referred to) They advertise some conversion kits, but not specifically the one you need.

They can probably steer you in the right direction. The mods will be worth it because the 270 has a good reputation and you get the electric trim which is important. I think the 270 is rated for 270 hp. If the gear ratio is much different from the 100, you will need a different pitch prop.

Make sure the transom is very well sealed if you have to cut it!!!

Welcome to the forum.

jim

 

Nice to meet you.

Thanks for the welcome, Jim. The hardest part of this conversion would be re-working the area around the existing outdrive mounting flange to accept the new one. I was hoping somebody here has already converted from their old AQ100 to a newer drive unit so I could get some tips on how they re-formed their angles and radii. As far as sealing the transom, I'm considering using wood forms and Seacast to fill any unnecessary voids left after the new cuts are made. The only void I can foresee would be from the "bump" on top of the old transom where the manual tilt latch sits and the hole just beneath this where the hydraulic tilt cylinder passes through. Using the rough measurements we got the other night, I honestly don't think this area will be exposed anyway. I would still like to fill it anyway to ensure a solid, tight seal and to better solidify the transom and hull under the new outdrive mount.

Something I found odd; the transom doesn't appear to be attached to the back side of the hull, but rather very slightly spaced from it and held in place by the sides and floor of the hull. From what I've learned from other boats, the transom is usually "skinned" with fiberglass, both from the hull side, and on the inside of the engine compartment, making a solid mounting point in all directions. If the pulley side (front) of the engine is pulled up and down, the floor flexes slightly, and the engine has the ability to move up and down by a small amount. Are these boats just that light, or does something sound offish about this?

Thanks,
Joe

 

CORRECTION

I have a correction: The new unit we'll be installing is actually an AQ275, not an AQ270.

 

I am hoping that the company that I suggested that you call will be able to give you a template to lay on the transom to make the new cutout and mounting holes. I think that is your best bet.

Does the transom flex when you move the engine?

jim

 

Thanks. I plan on calling them sometime this coming week to see about getting a template. We could actually make a template from heavy posterboard, basing it on the new outdrive's flange, if need be. I'm with the boat right now, and it turns out that the transom boards are touching the hull down along the middle of the back of the boat... they are only gapped near the ends of the board. The transom is very solid, and doesn't flex when the engine is moved. It's actually the hull flexing. Apparently, I didn't realize how hard he was trying to move the engine. I guess I was jumping the gun a bit.

I suppose I'm just not used to the design of this boat. Do you know about how the upper and lower halves of the hull were put together?

I'll try to get some pictures of the transom area and the newer drive unit on here tonight.

Thanks,
Joe

 

Joe,

There is a member that has restored a 17 which is similar. I would PM him and ask that question. I think he posted under Hydrodyne boats. He is not hard to find. I have never seen one up close. The 18 ski boats are heavy duty.

Some of the members do not check the forum that often in the winter due to the inactivity.

My boat is a converted I/O and I added some re-enforcements in the transom area which are probably not necessary. My transom is tied to the deck now.

You could easily tie the transom to the deck if you feel it is necessary.

jim

 

Ok, thanks Jim. It may not be a bad idea to glass the transom to the deck. After discussing it, I think we've decided to stick with the original drive. They are just too different for what we'd like to get into at the moment. Going up in flange size isn't a problem, but if he just plain and simple doesn't like the new unit or wants to go back for whatever reason, going down in size would be a bit of a problem.

Thanks,
Joe

 

You might want to keep your options open in case the old drive is no good.

jim

 

That's a good point, too. The existing drive should be fine, as the boat was bought from a friend, but we'll still hold on to the new drive anyway... especially since the boat I'm looking at buying has this type of drive on it.