Motor mounts/stringer spacing?

[Conquistador_del_mar]

What type BBC motor mounts do you guys suggest installing for a Bravo installation? Also, what spacing between the stringers would be best if placing them over the strakes is not an issue? I think the stinger spacing will be partly determined by the engine mounts. Typically, I have seen 24" - 26" stringer spacing. Thanks in advance. Bill

[gcarter]

Bill, have you seen this?
http://www.donzi.net/forums/showthread.php?t=58107
It's all driven by the strake spacing.
On the "newer" wider strake and stringer spacing, the mounts go inside the stringers.

[Conquistador_del_mar]

Bill, have you seen this?
http://www.donzi.net/forums/showthread.php?t=58107
It's all driven by the strake spacing.
On the "newer" wider strake and stringer spacing, the mounts go inside the stringers.

George, I had read that thread with some very good information, but I need some suggestions on what someone thinks are the best engine mounts for BBC with the Bravo installation and the resulting stringer spacing. I am leaning towards the L bracket bolted to the stringer with the adjustable height mount bolted to the top of the L bracket, but I wanted to see if there are other suggestions. For instance, I don't see how someone can tweak the alignment using the racing engine mount type that extends between the stringers, but I am open to suggestions. Thanks, Bill

[mrfixxall]

George, I had read that thread with some very good information, but I need some suggestions on what someone thinks are the best engine mounts for BBC with the Bravo installation and the resulting stringer spacing. I am leaning towards the L bracket bolted to the stringer with the adjustable height mount bolted to the top of the L bracket, but I wanted to see if there are other suggestions. For instance, I don't see how someone can tweak the alignment using the racing engine mount type that extends between the stringers, but I am open to suggestions. Thanks, Bill


Bill, i have a few if you need them,im switching the formula over to race mounts..

[Just Say N20]

Not to hijack the thread, but I have what appear to be "custom fabricated" engine mounts through-bolted to the stringers in my 16 (Volvo SBC).

IF I have to replace the stringers, do I want to re-use these mounts?

If I reuse them, how the heck to I position them correctly to insure the engine is aligned properly?

My inquiring, inexperienced mind wants to know. :confused:

[BigGrizzly]

Delmar, My mounts go over the stringer via a 4 inch angle and is bolted to the angle. My stringer is 1980 spacing which was common to almost all boats at the time, I think 26 inches.

[MOP]

My stringers are 25-1/2" on center an almost 2" thick, the stringers were doubled when they were done over. The doubling was done to the inner side dimension, it is a SB but the mounts are in the exact same place for a BB. As you see I used 1/2" aluminum angle set in 5200 with no backer plates, I felt with the stringer beef and extra layup they will never go anywhere being twice as strong as stock. Some worry about stringer flex that can be eliminated with gussets, I added 3 and another bulkhead forward of the engine mounts and two aft of the mounts. Two gussets are under tha battery mounts. A ton of over kill for my 383 mouse but who know someone might want to stuff some serious power in one day and will have zero sweat with the structural stuff.

[Just Say N20]

MOP,
Tonight a friend and I removed the 4 gussets that were added most likely when Marshall replaced the engine/drive. All 4 of them were broken free at the outboard/pointed end.

We drilled some 4.5" holes through the inner fiberglass surface of the stringers to see the wood condition. Tapping with a hammer showed most of the starboard stringer was delaminated (wood separated from the glass) on the outside, and solid on the inside.
The port stringer sounded solid through out except for one small spot.

However (pictures to follow) the wood was black and soaked everywhere we accessed.
I was thinking that I would pre-make a stringer/gusset unit for each side that would drop in outside the existing stringers and sister them together.

I'm still trying to figure out the engine mounts. I was thinking I might try and get a cradle type that mounted between the stringers. However I am certainly open to suggestions.

My stringers are 8" high and 24" apart inside to inside. The fuel pump barely cleared the starboard stringer, missing by less than 1/4".

[Conquistador_del_mar]

Delmar, My mounts go over the stringer via a 4 inch angle and is bolted to the angle. My stringer is 1980 spacing which was common to almost all boats at the time, I think 26 inches.

Randy,
Are yours like MOP's below your post? I talked to George a little this afternoon, and he made it sound like you had a plate that went between the stringers? Thanks for the spacing - that seems to be a standard. Bill


My stringers are 25-1/2" on center an almost 2" thick, the stringers were doubled when they were done over. The doubling was done to the inner side dimension, it is a SB but the mounts are in the exact same place for a BB. As you see I used 3/8 aluminum angle set in 5200 with no backer plates, I felt with the stringer beef and extra layup they will never go anywhere being twice as strong as stock. Some worry about stringer flex that can be eliminated with gussets, I added 3 and another bulkhead forward of the engine mounts and two aft of the mounts. Two gussets are under tha battery mounts. A ton of over kill for my 383 mouse but who know someone might want to stuff some serious power in one day and will have zero sweat with the structural stuff.

I am thinking about doing mine like yours. Talk about strong with those extra gussets and bulkhead! I will be adding some extra strength, but I haven't figured it all out just yet. I should probably wait until I have the engine, but I wanted to get the engine compartment built up and gelcoated. Thanks, Bill

[gcarter]

I talked to George a little this afternoon, and he made it sound like you had a plate that went between the stringers? Bill
Bill, sorry for the confusion!!!!!
What I meant was Randy's stringers are sandwiched between plates on the inside of the stringers and the stock mount angles on the outside of the stringers.

[MOP]

Our Donzi's are one of the greatest designs ever conceived but built to NMMA standards about the same as any other out there, they have some faults but all are easily correctable. Just about every Donzi bilge I have seen the gussets are coming loose to one degree or another. As noted above they start to separate from the hull at the outer tips, this is due to the hull flexing upwards obviouly needing more beef. If you run hard or add more power beefing things up is very important. Ted (Mr. X) went to great lengths to beef his hull for the Ilmor transplant, George and several others have also done so. As some know most of my hull upgrade work was done by the head glass guy from Hustler boats, his first comment on looking mine over was never put any big power in there. That comment came from some one who knows what it takes to keep a 100+MPH hulls together. It has been noted that the 22's of the 80's were the best built, that is true to a point. They have a weakness in the fact they have little to no support it the tub/deck to hull. When I first got mine it would crackle loudly under the back seat, that was due to the glass holding the battery box to the hull had torn away it was suppose to support the seat, tub/deck. Anyone that owns an 80's boat should look into beefing that area up! In the link below you can see what I found, look at the battery box bottom that is all that was supporting the aft part. Note the added support hull to deck struts by my gas fill hose I beefed that area to an extreme, I added hull to deck struts and built a very strong platform to support the seat area. Many have noted the tabbing from the hull to the tub was torn away, I did not have that issue as mine had no tabbing tub to hull!. In the link below look by my tank fill hose you can see the hull to deck struts I added to support the hull to deck that is only half what was done. I need to shoot a couple more photos. http://www.donzi.net/forums/showthread.php?t=58107

[MDonziM]

Bill,


this is what I did this year w/ my 22. The brackets are 1/2 alum which would be overkill w/ an 18. I used the standard merc. eng mounts.

[Conquistador_del_mar]

Thank you, guys. I will be beefing up the engine stingers when I install them, and I will show the end result. I was trying to see if anyone had other suggestions on motor mounts or spacing of the stringers, but it looks like I will use the conventional approach. Bill

[Conquistador_del_mar]

Bill,


this is what I did this year w/ my 22. The brackets are 1/2 alum which would be overkill w/ an 18. I used the standard merc. eng mounts.

That is a nice looking set of mounting pads. Thanks for the idea. What is your stringer spacing? Bill

[gcarter]

That is a nice looking set of mounting pads. Thanks for the idea. What is your stringer spacing? Bill

Bill, Marshall has the later styled boat w/the wider spacing (28"+/-).

[MOP]

There is another problem looming on the horizon with some later Donzi's. When you pull the cover off to access the engine mount hardware it is some wet and slimy under the engine room shelves/floors. Trapped moisture will lead to issues down the road, I think we have already had a few turn up with issues I know one was a Blackhawk. Not sure if Donzi addressed it in the newer ones, but ventilation must be provided to those two cavities!