Engine Box Modification Questions?

[Vince Luciani]

Hello everyone,

Thanks for the responses to my earlier repowering questions. The information is very helpful.

I’ve got another question. Does the rear bulkhead nead to be relocated or do the engine boxes/covers need to be enlarged to fit the Cummins 6BTA engine. I’ve been looking at various pictures of Bertram 31 repowers and it looks like I’ve seen them done both ways. For example, on JK’s “Seanile”, I believe the boxes have been lengthened. On Tony Athens website, there are photos of a Bertram 31 repower which show that the bulkhead has been “bumped out” in the engine area. However, in the pictures of John Jackson’s boat that John has sent me, it appears that the boxes have not been lengthened.

I’m guessing that a lot depends on how close to or how far from the bulkhead is that you mount the engines. I think I remember reading that as close to the front bulkhead as possible is best?

Can anyone shed some light on this topic. I’m trying to plan out my project as best I can. Thanks again.

Vince Luciani

[In Memory of Vicroy]

Vince - on AJ the boxes and bulkhead are original and the 6BTAs fit fine. The front of the engines are about 3 or 4 inches from the bulkhead and the belt cover needs to stay off. My 250s have the top mounted aftercooler and with one inch Soundown in the boxes, the top of the aftercooler rubs the underside of the Soundown.

UV

[In Memory Walter K]

I have a 64 Sportsfisherman with the old style 2 piece engine boxes and the engines fit, but as Uncle Vic, the belt shields were removed. I see no reason to move a bulkhead or elongate the covers. Walter

[Cross]

My 72 FBC was repowered this summer with 330 QSB's. The engine placement (inches from the bulkhead) required the fiberglass deck to be pushed aft about 2 inches. This movement of the deck required the boxes to lengthen by the same amount. John McCallum at Taylor's Boatworks in Morehead City, NC made the change. You can not tell a change was made. I do not know if there is a difference in the overall length of the 6BTA's vs. 5.9 QSB's.

[In Memory of Vicroy]

Cross - how do you like the QSBs? Give us some performance numbers. If the old 6BTA 250s ever go out on AJ that's what I want to put back in. Quiet?

UV

[Capt. Mike Holmes]

Capt. Pat and everyone else - practically - thinks these boats do best with more weight aft. When I did my repower, I mounted the 6BT's far enough back that I have about 10 inches between the harmonic balancer and the cabin bulkhead. This is a huge help in getting to belts, etc. on the front of the engine. Had to move the boxes back some, but instead of modifying them, I added a hatch in front, allowing quick access to the front of the engine to look at belts, water pumps (mine are on the crankshaft pulley), check and add oil, etc. I have a 1962 express, with the big heavy boxes with front and rear hatches, so it's a different situation than with a flybridge cruiser, sportfisherman, or Bahia Mar. By the way. my engines and trannies (Twin Disc 5011A, 2:1) lined up much better with the big struts from High Tide when the engines were moved back.

[John Jackson]

I have a feeling that I am going to have to somehow modify my port engine box to fit the port engine exhaust elbow on the 270B It's going to be close. I have looked at about five boats with 270bs, 250s or 330s and they all seem to fit in the space. I'm almost at the point where I will know for sure. I will let you know and send pictures.