I am wondering about my hull shape speed wise

Tabs effectively do just that (change hull shape). A hook is drag both above and below the target speed range. Hell, it's drag all the time, but within the speed range it's usefulness can tolerated.

 

717,
Changeable hull shape?
There is a kayak that does that now. Increases and decreases rocker significantly.

 

Neat, I am thinking a hull that could morph from displacement to planing.
Change the deadrise at the stern.
Maybe could use a folded wing like tab on the bottom.

Robots can transform into cars, trucks and planes, so I think it is possible.

 

It would appear that years ago both engines would only get to 3500 . Now the STBD engine gets to 3000, then the STBD engine is not reaching full hp to turn the prop that fast.

Target the STBD engine.

If the design rpm was supposed to be 4000, way back when, then the props were wrong then and perhaps with more weight, less horsepower, especially from the Stbd engine, this over prop situation has become more pronounced.
You could see if someone would lend you some less pitched props and check the performance.

The bow up, stern down issue is due to the fact that you cannot generate enough speed to get over the hump due to some or all of the following

1) stbd engine is not producing the same hp as the port engine
2) you have had a weight gain
3) you are incorrectly propped

 

Barry,
You've gotta be right.
Not enough oomph.

 

yes, likely the HP was down on the starboard engine.

I have replaced the fuel pump, which actually failed on me, left me with dead motor.

I pulled distributor and repaired the advance weight bushings, they were plastic and were actually missing which would prevent the full mechanical advance of the ignition timing from being realized.

I tried to time the engine with a light, but my light is broken apparently, the brightness is gone. I think I can rent that from AZ for free.
Timing is supposed to be set at 10* BTDC on IH 392 Palmer marinized motors.
The flywheel faces bow, the crank nose drives the trans and timing is done on cylinder #1, not cylinder #8.
On the flywheel is stamped the marks. It is a tough place to see correctly. I may have last time had to remove the batteries which sit between the motors to do that.

Found this, you can statically set the timing. One thing though, you must not back the engine to the timing mark since exists play in the gearing, you must rotate in the same direction to make sure the play is taken up in the gears, otherwise, it will be off several degrees. If you turn it too far as in past the mark, back up the crank an inch or two and move it to the mark again.
http://www.mgexp.com/phorum/read.php?1,2330372

And a light bulb. But as I was thinking of this, a spark coil fires when the voltage goes away due to field collapse, so it would be bulb turns on, keep twisting till bulb goes out.
http://mgaguru.com/mgtech/ignition/ig205.htm

If so, then a volt meter will work. An MG, the distributor turns CCW, so for distributors that turn CW, reverse their distributor twist instructions.

Adding in this.
The miss at 2000 rpm is gone. The change was I gapped spark plugs to 0.040 up 10 thousands from 0.030.
I got it statically timed and it starts and runs well in the slip.
I cant test it yet, the other motor I have an AN8 hose end swivel cracked oil fitting I need to replace. Got the part today.

And I aligned engine, I found prop shaft was rubbing on the shaft log, but don't know If I already mentioned that. Other engine is ok.
Last time we took it out, it was hot, so some friction may have worn the inside of the shaft log. Next haulout I may have to build it up with copper and silver brazing. Shaft log is bronze.

 

Did some more investigating, and I think the starboard prop shaft is bent.
I was watching and feeling the running engine today.
At 1200 rpm, the engine is smooth, the prop shaft is smooth.
At 1500 rpm, the engine is smooth, the prop shaft seems to be slightly not smooth.
At 2000 rpm, the engine in the rear is moving around shaking, the prop shaft is not smooth running, it is also visibly bouncing around. Lot's of vibration going on.

I remembered a few year ago, I hit a rock or something hard in the water with that starboard prop, big enough that at the haulout, one edge was curled and I straightened the blade edge. So maybe it got bent, the prop and the prop shaft.

I suppose next haulout, I need to pull the shaft and prop and have them checked.

 

Well, more info. The engine has shifted since I aligned it.
I noticed last time out a lot of shaking going on, so I rechecked the coupling and it is off by .015". That I suppose is a lot!

I may have to redrill the rear adjustment holes for the rear mounts, maybe use better lag bolts, like SS. The holes are too far one way. For the coupling to align, I have to push the rear mounts all the way to the extreme end of the slot, and one of the holes years ago I drilled crooked, which does not help keep it in place. That actually goes back a long ways to years ago when I had the bottom off, when I remounted the strut, it was a little bit off the mark I think.:!:

So maybe shaft is not bent at all. At idle in gear, it sure looks to run true.

How much vibration would 0.015" out of line would be experienced? To align , I have to shift rear of starboard motor to starboard.

When I redrill, I will epoxy in a wood dowel to fill the hole. The new hole wont even touch the old hole.

 

Updating this thread. I have started taking apart the starboard engine.
The heads look good, all exhaust valves are clean tan.
The cylinders look really nice, no gouges or lines you could feel.
Top of some pistons show a little pitting on the edges, likely from detonation event in the past. The pistons are .030 oversize.

Someone had mentioned detonation event could have damaged the rings or ring lands which could keep the rings from moving which could explain the oil burning- compression loss at high rpm. So glad to see smooth cylinder walls.

In a couple days, I will post some pics.

I am hoping I can just put in new rings and valve seals to get this motor running good.

 

Ok, some pictures

Hauling it up out of bilge. this worked out very well. Cylinders got tiny amount of surface rust from humidity. It came right off when pushing out the pistons.



Draining the oil, I left it lifted to do that, then dropped pan after.

 

The main bearings are worn, some showing copper.
The rod bearings don't look too bad.
I will replace all bearings, rings, seals.

I cc measured the heads and pistons. I ground the exhaust port for better flow.
IH 392 are in need of some exhaust port help, mostly the bowl area.
Intakes I left alone, don't want to disturb the torque output rpm.

My history with this engine, 10 years or so ago, I shaved heads .050 to boost CR from 8:1
However it pinged mercilessly regardless of retarding the spark. So i doubled up the head gaskets.

This time I learned that combustion chamber sharp edges, and these had plenty, can cause that. So I ground the knife sharp edges on the head chamber edge. I also unshrouded the intake valve.

The values for the cylinders, I measured using a syringe and clear plastic plate are
Combustion chamber 80.75cc
Piston relief D cup 8cc (Definitely!, not 13cc)
Bore 4.155
Stroke 3.656
Head gasket 0.45
piston deck height .035 in the cylinder hole?? Not measured yet it seemed large. What is typical?
Using this calculator, cr is 8.6, which it seems should work ok on 87 octane regular gasoline.
https://www.rbracing-rsr.com/compstaticcalc.html

So what do you think can I run it using just one head gasket, not two head gaskets?

 

Strike a light ! That engine block balanced precariously on a relatively flimsy ladder is a bit of a worry.

 

Stripped to a short block, it's not all that heavy, maybe 300 pounds at most. The ladder is probably rated below this, but with a reasonable safety margin built in, it'll hold.

 

yes, it holds my weight too at 200 lbs. The weight is spread equally across both ends of the beam.

I have done all the calculations.
My original failed goal 10 years ago was to experiment with higher compression by shaving the heads .050 to make it more efficient and more power. So at this moment, I decided to try and understand what went wrong, and how it could be fixed ti use this head more like my original intention.

I have run through all the SCR and DCR calculators. And measured the cc's of head, gasket, cylinders etc...

Using a single head gasket with shaved head of 0.,050
Chamber is 80.75 cc
Gasket is 14.4 cc
piston height in the hole is .035, so 7.77 cc
cylinder is 812.34 cc (.030 overbore, 4.155 x 3.656)

Total cc is 915.26cc
SCR is 915.26/102.92 =8.893
DCR = 8.62:1, way to high for 87 octane gas, which is why it detonated so badly.
http://www.wallaceracing.com/dynamic-cr.php

So I doubled up gasket
Chamber is 80.75 cc
Gasket is 28.8 cc
piston height in the hole is .035, so 7.77 cc
cylinder is 812.34 cc (.030 overbore, 4.155 x 3.656)

Total cc is 929.66cc
SCR is 929.66/117.32 =7.924
DCR = 7.69:1 , ok for 87 octane gas, which is why it no longer detonates at all.



So now to get more of what I wanted before, idea is to change the camshaft, use a single gasket.
Going through calculations again, the SCR is 9.5 and DCR = 9.2, way too high compression for 87 octane.

To get it not ping, camshaft needs changing. OEM camshaft, the ABDC is about 25*
I found one with ABDC of 68*, then the DCR is 7.35:1, lower than what I have now for the DCR.
I will keep looking for more camshaft ideas, etc...

The cylinder cranking pressure also has been matching with what it should have around 140 to 150 psi.

 

Engine is back together and runs very good in the slip.
It is setup without major mods to the CR. I did port the heads, mostly the exhaust ports.
Have several run videos in the album.

https://photos.google.com/share/AF1...?key=NVZlQTNmblNxOXJUd1JHT3dMUDRCR0EtQ2ZmeGxR