Not another Mustang restoration thread.

Hollywood wrote: How come boats with horizontal cracks at the water line also have a separated floor? No floor to hull bond = bad Strong floor to hull bond = bad? Light floor to hull bond = good?

Stress concentrations on flexible surfaces bad - how you avoid/cure them can be many ways - including removing the flex of the flexible surface.

The horizontal stress cracking I have on the passenger side of my ski nautique was certainly at the wettest area of the floor/foam and had disbond of the floor at that location. Was there an impact or flaw that caused the cracking, Disbonded the floor, let in water and caused the rot or was there rot/wet foam that froze, expanded, and pulled the floor away from the hull causing the stress cracking.

If I had to guess I would say the latter scenario was more likely as there was no cracking of the glass anywhere just separation, but I can't rule out a bad floor to hull bond from the factory.

Relatively rigid well bonded foam in the floor changes things quite a bit...

John

My keen x ray vision seems to think there's a Pertronix module cleverly hiding under the distributor cap.............or maybe it's the red and black wires telling me that

Could you put an orange oil filter on the engine to go along with the Pertronix module so Pete will be clutching his heart and mumbling something about "the big one"     

Eh, the chrome engine bits look great, as do the polished hull hardware... paint the rest.

This is what ours looked like 10 years ago. I bet they don't look like that now...

John, I could be wrong but I think placement of the front mounts is dependent on shaft length once the distance between strut and prop are set rather than a set distance from the factory.

I've been down this road with the promo when we swapped the 318 for the 340 and installed a new ARE shaft. New shaft was intentionally shorter but we still ended up moving everything back 3" in order to get an optimal measurement between the strut and prop.

I'd say it's better to test fit what you have to ensure everything works together. My thought would be to install the shaft (with coupler and prop) then drop in the engine and slide forward or backwards based on distance hanging off the strut.

You can shim higher, but not lower. Make sure your stringers/cradle aren't too tall. Do a test fit after your framing is glassed in to make sure you're within the tolerances to align. Install your strut, shaft log and shaft/coupling and make sure it'll line up with the new stringers/cradle.

#2 will obviously require a test fit of the shaft to make sure you are aligning the strut to the log.

4 and 5 are swapped.

2” x 2” x 1/2” angle? Now you’ve lost me.

#2 will obviously require a test fit of the shaft to make sure you are aligning the strut to the log.
I understand the need to align the log to the strut prior to engine alignment.

4 and 5 are swapped.
I am confused by this. My thought is that the front mount must be secured to the stringer prior to alignment, but the lateral alignment adjustment should be left loose to slide the engine for alignment, and the rear mounts should be loose to slide the wedges for elevation adjustment. If the front mounts are not secured to the stringer there would be no lateral stability. As you know the H/M mounts allow for several inches of lateral adjustment.
Is my thinking seriously flawed?

2” x 2” x 1/2” angle? Now you’ve lost me.
I plan on through bolting 2' X 2" X 1/2" thick aluminum angle stock to the stringer since Coosa does not hold lag bolts well. This will raise the height of the stringer 1/2" in the engine mounting area which is about 3' on each stringer.

I don't think I've ever seen 2 x 2 x 1/2.

I've seen 3/8 thick but not 1/2

How about a picture of this stuff?

I share kens skepticism on that size angle being available. Even if it were, it would leave you with only 1.5” inside height. Center the through bolt in that 1.5” and you’re within 3/4” of the top of the stringer (then subtract bolt radius). Awfully close to the top. I’d go a lot taller (at least 4” but I’d aim for 6”).

I also don’t love the idea of drilling and tapping the angles for the mount bolts. Why not scallop the stringer and through bolt the mounts/wedges similar to the way it was done in the 80’s?

If you’re trying to determine engine placement, I would do a gross alignment check first (engine floats until you’re happy with its location), then lock it down, then proceed with the fine alignment using your adjustment features.

TRBenj wrote: I share kens skepticism on that size angle being available. Even if it were, it would leave you with only 1.5” inside height. Center the through bolt in that 1.5” and you’re within 3/4” of the top of the stringer (then subtract bolt radius). Awfully close to the top. I’d go a lot taller (at least 4” but I’d aim for 6”). I also don’t love the idea of drilling and tapping the angles for the mount bolts. Why not scallop the stringer and through bolt the mounts/wedges similar to the way it was done in the 80’s? If you’re trying to determine engine placement, I would do a gross alignment check first (engine floats until you’re happy with its location), then lock it down, then proceed with the fine alignment using your adjustment features.

I could go with 3 X 2 X 1/4. What is the concern about drilling and tapping the mounting holes? I am not familiar with the 80s mounting method. I believe having a channel about 3" long will provide plenty of room for multiple through bolts to secure them.
1/4" aluminum angle stock

8122pbrainard wrote: John, I agree with Ti'ms concern. If you do move forward with your current plan, I do recommend going with the 3/8 plus using fine thread bolts into the angle. This will give you more threads in the relatively soft aluminum. His other concern of getting the through bolting low enough in the stringer can be overcome with using a 2x3 angle with the 3 leg down.

Brain fade. Yes, I agree. I am typing 1/4 when I mean 1/2. The 3/8 is available and my fabricator can get or make 1/2" Don't know why I was saying 1/4 and referring to bringing the height up 1/2.

Thanks for the suggestions. I like the method of scalloping the stringers and using nuts to secure the engine mounting bolts. I will order the 3/8 3 X 2 angle and plan on doing it that way unless someone has other input.
It's nice having an engeering team with decades of experience willing to help a guy out. This thing just might turn out ok.
You guys are truly the best!

A little progress tonight. I shaped/fitted one primary stringer and got the second one cut out and ready for shaping./fitting. I am considering making 2 small passages between the stringers and the floor to allow water to drain to the bilge. The originals had 2 holes each side for that in the area where the exhaust hose lays. Without foam some water may collect there. Is this a good idea? I am also considering not installing the original floor pan. It has some damage around the pylon where the PO enlarged the hole slightly for an extended boom support. The trim ring almost covers it but not quite. There is also significant wear where the front of the motor cover rests.. I have more than enough storm gray Nautilex left over from another project to do the floor. If I don't like it the Nautilex it should work as an underlayment for the pan.
Work resumes tomorrow.
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