It doesn't look like you'd need to cut your floor at all for those cast aluminum mounts. But if other people are using the mounts similar to yours without any problems...

He will have to cut the floor away if he switches to the glenwood style mounts. There's a floor that that runs from the lifting strake and butts to the stringer. That will have to be removed, or an acess hole cut into it, to have access to the bolts holding the feet in. Normally this area has the floor on top of the stiringer, or none at all. Never to the center of the stringer. Kinda strange. 

bingo

You can see that the pan is very close to the intake, about 7/16". The problem was the intake had to be set abit high to be flush with the keel.

Engine removed again so I could drill the intake for the through bolts for the loader.

Nice photos and it'll help me when I do the repairs while my engine is getting rebuilt.  My bolts going through the stringers are carriage bolt that have been sucked up so far that they are almost buried in the wood.  Those will get pulled, plugged and glassed over.  Then I'll put aluminum backing plates so this won't happen again.

Do you have any good suggestions as to how to make sure I get any oil removed from the wood without replacing the stringers before I glass them in?   Nice work!  Greg

They make stringer washers to keep the bolts from getting "sucked in" I think you can even get powder coated ones to add to bling factor

Too bad the previous owner didn't use some sort of washer but not one on the stringers.  So now I get to deal with making it right.  What else is new. 

In my opinion the best way to fix your problem would be to get some flat 1/4" thick by 4" wide and span it the length of the motor + maybe 4" past each side . Drill it and then use the stringer washers . Similar to a rail kit . It disributes the weight of the motor across a larger span on the stringer . Alot of times people fix shit with a band aid and here we are fixing a band aid . This all only assuming your stringers aren't rotten on the inside .

Great thread too Jim . Very informative and a great lesson .

-beerjet-

Well, I can go get some 1/4" x 4" x 8' aluminum plate and that will give the 3' needed to span the motor mounts plus 4" in each end.  I'll post some motor mount photos in a few minutes.

I bet that is a factory install on the carriage bolts. I have seen that quite a few times.

The best way to handle this is to, drill out the rotted wood and install a hard wood dowel. It is important to make sure you do not have any black or soft wood remaining after drilling. You will then grind out a divet that is aproximatly 1/2" - 3/4" larger than the dowel hole. This way you can lay two layers of fiber glass cloth to help secure the repair. Now to install the dowels you will want to make up some resin and completely saturate the dowel and install, you should have to tap the dowel in with a hammer. Now the new engine mount bolts need to have a long shoulder that extendes the width of the stringer and the foot of the mount with the stringer washer in place. This way the slight movement of the engine does not cause a sawing action from the threads, causing oval holes. Bergeron Marine has some very nice stringer washers, that come in many different diameters and colors. I use the real large diameter washers on the thin stringer boats or on the high HP applications. After you do the repair it should last two of your life times as the one that we are discusing has lasted probably 25 years already. Remember this is not a race boat, it is a lake/river hot rod.

Here are a few pics of the dowels installed and one of the bilge prior to work.

Here are a few more pics;