Engine Alignment H-27

[HN]

1978 H-27:The plywood blocking for the shaft strut became soft due to ice damage over the winter. I repaced the blocking, new screws, washers, nylon locking nuts and sealant. (The shaft was still coupled to the engine). After this operation the shaft is more difficult to turn. I assume that the shaft and engine are now out of alignment. 18 months ago I replace the shaft so I know the coupling will come apart. The documentation that came with the boat says to "separate the coupling, move the shaft back to clear pilot in center....Establish the shaft on the center of the log until it touches top of log". Question #1: What do they mean "to clear pilot in center"?Question #2: Any better description on how to "center the log" would be helpful.I'm pretty handy when it comes to this type of thing, but is this a job best left to the boat yard mechanic. I'm from the era when we actually used feeler gauges on the car points so a .003" measurement isn't a problem.Thanks out there.....

 

[Steve W]

try this

I just did my first engine/coupling alignment on my Newort 28 and it is very easy, just plan on being patient and thorough. Seperate the coupling and pull the coupling halves apart completely. Then move the coupling back toward the transmission and center it to the transmission side of the coupling, but don't let them touch. You may have to prop up the prop shaft side to keep it from drooping, so they visually match. Check the gap at 12,3,6,& 9 o'clock. The objective is for the gap to be within tolerance, probably .0040, all the way around the coupling. After taking the measurements, adjust your motor mounts to bring the gaps within tolerance. I know this is a poor description of how to do it, but once you start, it is really easy. I solved a vibration problem with just a simple turn of the wrench, once I knew where the aligment was off. Good luck!

 

[Doug]

Centering the Shaft

The first attempt I made to align the shaft on my 89 H30, I didn't center it in the shaft log. And I didn't correct my problem.I had a knocking at certain RPM's and wouldn't think of going over 2800rpm due to the banging. I slid the shaft back enough to clear the pilot. That's the extruding part on the shaft flange that fits into the transmission flange coupler. The trick is push down on the shaft to the lowest point and take a measurement - pull up on the shaft and take that measurement - then half it - that is where the middle of the shaft log is. Do the same side to side. You can cut two angled pieces of wood to wedge the shaft in position - I took an old rubber bedliner from a pickup truck and cut several blocks about 1 1/2" sq. to shim a block of wood under the shaft. When you have it centered - adjust the engine up, down, over however you need to align the flange edges. Then slide the coupling together and do your fine adjustment with the feeler gauge. I marked the nuts on the engine mount so I had a reference of how much I moved them and where the starting point was. The result was I needed to raise the shaft 3/16" and it made all the difference. I was thrilled when the knocking noise was gone! And didn't have to pay $500 to have the boat pulled out of the water.DougS/V Brenda Gail

 

[Tom M.]

engine allignment

First of all, the shaft, has no adjustments, per say, just linier, the engine has the four mounts, so you must disconnect the engine/trannie, at the coupling on the shaft, and disengage it, meaning seperate the two a little, and let the whole thing sit for a day, then you can turn by hand the shaft to feel if there's any unneccessary, resistance, then when you release the engine and allow it to engage, both coupling flanges should mate up, now you must use a feeler gage around the coupling flange perimeter, to properly tilt, raise, align this gap as colse as you can adjust it, by use of the four mounts, .002" feeler, then start drawing your bolts up evenly: 12o'clock, then 6, 3 o'clock then 9 etc always checking the gap, for any minor misalignment, until they are tight, now if the pilot diameter, is not in line, you couldn't get to this point at all, now "to clear the pilot," you did that, when you disengaged the coupling, it's a male shallow plug, and a female shallow counter bore recess built into the couplings.