View Full Version : aligning the $#@%! shaft...

Thaddeus J. Van Gilder
05-30-2003, 08:31 AM
Have any of you installed a new engine, and had it so far off that it takes days to get the thing even close?

my new engine is as far south as the mounts will allow (in the frount), and it is still to high.
I have to remove 1/2 inch of engine stringer, and I hope that's enough.

I am going from a 1950 or so air cooled 7 hp (1,000 plus pound) Enfield diesel, to a 250 lb 1978 12 HP yanmar.

This has to be the worst job imagineable. I would rather scrape the bottom paint 8 times and eat all the paint chips, without a powerwashing!!!!


05-30-2003, 08:35 AM
Sounds like it's too late for this, but maybe not... if you can easily remove the engine you may want to build an engine fit template--all you need are accurate placements of the feet and shaft. It's a lot easier to fiddle with support adjustments using a 40 pound template than a 250 pound engine. My old yard used them with great success; ideally by the time you drop in the engine you are pretty sure it will already fit.

05-30-2003, 08:41 AM
Thad, sorry to hear about your grief. Erik's idea does make things a lot easier. I've been there, but I had the oportunity to 'suspend' the 550lbs of cast iron in place before the engine beds were there so I could take measurements & make the engine beds come as close as I could. (I still had a good bit of fitting to do.)

Thomas Garber
05-30-2003, 08:50 AM

I feel for your pain. I went through similar problems putting a Yanmar in my sailboat. Hours with me head in the bilge, trying to get my template aligned. If you get totally stuck, you might look into alternative engine mounts. I used this guys website as a guide http://www.triton381.com/restorationhome.htm Good Luck!

05-30-2003, 10:47 AM
Thad: I am not too familiar with the wee Yanmars, but on many bigger engines the mounting feet can be unbolted from the block, flipped over, and re-attached. This drops the engine about 3"-4". Might be worth having a peek at how the mounts are fastened to the block. You might also considering having custom mounts fabricated by a good welding shop before you go hacking at your boat's innerds.

Thaddeus J. Van Gilder
05-30-2003, 11:26 AM
Oh my god! I knew I wasn't drinking enough, I can flip over that front plate thing!!!!!

ken mcclure
05-30-2003, 11:58 AM
Originally posted by Thaddeus J. Van Gilder:
...that front plate thing...I hate it when these conversations devolve into technical jargon....

05-30-2003, 08:03 PM
Thad - one suggestion I would make is not to use the traditional double flange coupling arrangement. If you substitute a commercial roller chain coupling or even one of the roller chain and molded wrap around polymer insert types, they are much more tolerant of both angular and radial position variations than the bolted flange type.

Stop by a power transmission company and get yourself a Browning/Lovejoy catalog or equal and you will find them. And the polymer type do not need any lubrication.

Bob Price

Peter Malcolm Jardine
05-30-2003, 08:49 PM
Just my experience... I have rarely found that the existing or factory engine mounts lend themselves to A)adjustment B)removal C)repairs or overhauls. My CC mounts are the best I have seen only because they are easily accessible. My dad just replaced the mounts for his perkins by fabricating up new ones with bigger easier less complicated adjustments in stainless plate and threaded rod. Thad, I know you have an analytical mind... look at it and determine where the problem is and fix that problem by either modifying or changing the existing adjustments/bed etc.

05-31-2003, 12:03 AM
Thaddeus: Sure it's not one of the more joyful jobs. Whichever you do, change the mounts or plane off the bed, end up with the engine or transmission coupling a bit lower than the shaft coupling. Then it's easy to add oak shims between the mounts and the bed to bring the couplings in line. When you get close, you can use brass shim stock that comes apart in thin layers. A stout roll bar will easily lift at each mount, levering on the bed, one at a time, for installing the shims. You will want to realign (fine tune) after launching.

A bit of salsa picante helps get the paint chips down. Cheers.

[ 05-31-2003, 01:13 AM: Message edited by: Bayboat ]

High C
05-31-2003, 11:37 PM
Thaddeus, I have what may be the same engine in one of my boats, the Yanmar YSM12, circa 1979. If it's the same engine, with one horizontal cylinder, I suggest once you get your alignment problem solved, that you do everything you can to bolt that sucker as firmly to the engine beds as possible. This engine is not smooth running, and due to its horizontal cylinder, it shakes side to side on its feet rather dramatically in the lower half of its RPM range. It's a bugger on mounts. They tend to wearout faster than normal, and the nuts and bolts in the mounts tend to work loose. Use the longest, fattest lag screws you can put into those beds, use double nuts on top of the mounts, and loc tite on the threads, lots of it.

Mine has been behaving itself for a couple years now since I redid the mounts. And I just avoid running under about 2000 RPM (guessing by ear, no tach). It's pretty smooth above that, and tolerable at dead slow idle, but dances the hoola if I try to run it slow.

Edited to add: Mine has the flexible rubber mounts, BTW. I don't know if a "hard mount" bolted firm to the engine beds would help tame this engine, or if it would exaserbate the problem. It's worth looking into.

Good Luck!

[ 06-01-2003, 05:52 PM: Message edited by: High C ]

06-01-2003, 11:15 PM
Thad, I've been Re aligning my 1958 Greaymarine, about 450#, on original builders bed. Cutless on a strut and the rear Parasgon bearing. I let this get so far out of hand the strut web busted. The engine is definitly in a different place than it was 45 years ago. Alignment on top of the beds is/was with lags, on oak chocks with shims. For what it's worth, last time I had this little jewel out for a valve job, the replacement shims were purpleheart, the oak, and later teak chocks, compressed over time, requiring periodic shim adjustment, got it within 0.002, and then later, had to mess with it some more, to get it back. I also replaced the lags with through bolts, stainless allthread with the lower nuts, washered and either at the underside of the bed(s)
or set in pockets cut out, so didn't need to drill such deep holes. This being a gas engine, not too much vibration/jumping around. Never tried it but the chain coupling idea sounds like it might be a winner in your application, had experience with these many years ago on ships,
vertical electric driven pumps, filled with grease encased in a housing, many thousand hours, and no trouble remembered. Also local Yanmar and I suppose other Engine dealers/sellers who do installations have, the aforementioned alignment jigs available for their own purpose, but lend to engine purchase customers. Hope some of this ight help, cbob

Dayton Eckerson
06-03-2003, 02:46 PM
I installed a new 4 cylinder Yanmar in my boat last year, and yes, getting proper alignment is a bear. Here are a few things you might try/avoid:
1. The flexible Yanmar mounts that came with the engine were too tall and long for our installation. We used some smaller after-market mounts. Though they were less flexible than the Yanmar mounts, they have worked out fine.
2. If you use the Yanmar mounts, you must be careful to use the front mounts in front and the rear mounts in the rear. Although they look the same, they are designed with diffent levels of flexibility and are not interchangable.
3. If you need to lower your new engine below the existing engine beds, you can sometimes flip them over and use them upside down, i.e., mount them so they look like an "L" when viewed from the front. Alternatively, you can have new beds made up pretty easily using angle iron. For added strength, use one long piece for each side and have a welder weld in a "hypotenuse" every foot or so.
4. When doing the final alignment, put a drop light in the bilge under the coupling so you'll be able to see the light shining through the two coupling faces. This method can get you 98% of the way there without continually using feeler gauges.
5. Take your time. Perfect is close enough. Redo the alignment a week after you launch to account for any shifting from the hull taking up. Good Luck!!!

Thaddeus J. Van Gilder
06-04-2003, 06:47 AM
The hull is pretty tight...she has been in the water since last August.
I tried to flip over the front engine mount mounts on the engine, and unfortuneately I can only flip over the back ones...the front ones are not flippable. So I am back to removing some of the engine stringer.


06-04-2003, 05:10 PM
Ah yes, we have just finished aligning our 350 GM small block in our 23 ft mahogany runabout (new construction). what we did was install and align it last autumn and let it sit over the winter with the shaft not attached, then trailered it for about 100 miles to bounce and settle and all, and it was out by a fraction of an inch after all that. had to shave the front motor beds. all is within 0.003" now we will use a straigt coupler. wish us luck, mitchell in CT