Help installing Merc 454 in a 71 donzi 18

[kz1h5y]

I'm looking to install an 89 Merc 454 in my 71 donzi 18 and I have questions on proper engine mounting. What is the best method of properly mounting the engine to the stringers? I was thinking about wrapping the main stringers in the engine, including the cross support stinger just in front of where the engine mounts with 1/4" aluminum and using 45 degree brackets to tie it all in making a strong torqe box. Next, I was going to figure out a way to place the engine mounts directly on center of the stringers. If someone has done this before I would really appreciate some pointers, or just let me know if I'm heading in the right direction. This is a first for me! Thanks for any advice.

-Ross

[Mckillop]

How are you planning on getting the motor in the boat? I would imagaine you would have to pull the rear deck to stuff it in there. And even then, going to be a TIGHT squeeze if you can pull it off?

[mrfixxall]

I'm looking to install an 89 Merc 454 in my 71 donzi 18 and I have questions on proper engine mounting. What is the best method of properly mounting the engine to the stringers? I was thinking about wrapping the main stringers in the engine, including the cross support stinger just in front of where the engine mounts with 1/4" aluminum and using 45 degree brackets to tie it all in making a strong torqe box. Next, I was going to figure out a way to place the engine mounts directly on center of the stringers. If someone has done this before I would really appreciate some pointers, or just let me know if I'm heading in the right direction. This is a first for me! Thanks for any advice.

-Ross


First,which drive are you using? your plan of attack sounds rite so far,,make the engine as light as possible and i hope your going to use alunimum exhaust manifolds :)

[MOP]

We have several BB 18's on the board, outside of the BB sound IMO there is no advantage over a worked SB. in fact poorer handling plus no quick throttle downs as they take water over the stern.

[Rodger]

in fact poorer handling plus no quick throttle downs as they take water over the stern.

Yep, a few times I got wet sitting in the rear seat of a factory equiped 18' with a 454/TRS and cast iron Merc manifolds. The sensation wasn't too bad... on a hot sunny day.

[kz1h5y]

How are you planning on getting the motor in the boat? I would imagaine you would have to pull the rear deck to stuff it in there. And even then, going to be a TIGHT squeeze if you can pull it off?

My boat has a barrel back. The based on the opening measurements and the dimensions of the engine without the manifolds attached I should have 1 inch of play from bow to stern......so it should be interesting!! I may have to attatch the Bell housing to the engine while in the boat.

[kz1h5y]

First,which drive are you using? your plan of attack sounds rite so far,,make the engine as light as possible and i hope your going to use alunimum exhaust manifolds :)

I have a complete 1996 DPX-C transom and drive including all the exact steering goodies that I'm attempting to fit in. The initial measurements look like it will work with a little luck. According to Volvo the Drive weighs 130 lbs. So I'm only adding about 25 lbs. compared to the 105 lbs the 270 weighs. The change from the 351W to the 454 is my biggest concern. I am going with aluminum manifolds or headers.... all depending on what fits best.