Engine Alignment
 

Hi team. Quick question: Is there any need to ever change the height of the rear MerCruiser engine mount? Specifically, has anybody ever had to put shims in between the motor bellhousing ears and transom plate receiving holes? I have worked on 3 boats in a row now where no matter how the front mounts were adjusted, the drive would not go on (Alpha 1 Gen 1, and older). The drive would only go on smoothly if the motor was lifted very slightly with a hoist. I'm scared this is putting stress on the gimbal bearing and drive shaft. The boats are mid 80's and older using Chevy 350's (Merc 260's). Seems like metal to metal with a fiber washer in between, so I don't uinderstand what is changing.

At this point I am open to guesses, suggestions, and past experience please! Thanks for the words. I'm happy to chime in when I can.

Clint

Re: Engine Alignment
 

Engine alignment is extremely important. You need to re-drill the brackets or replace them if the holes are too close to where they need to be. Not guessing, past experience.

What is changing? Perhaps nothing. Many boats never are aligned right from day one. Are the motor mount race mounts or standard mounts? Are the stringers detiorated causing the brackets to move? If you have to lift the motor you got a problem that needs to be fixed.

Re: Engine Alignment
 

Thanks, but I don't understand your response. A typical MerCruiser setup has the rear motor mount as two vertical holes (horizontal ears with holes in them) which sit atop each other (bellhousing and inner transom plate). There is no adjustment that I can see. To raise the engine rear, spacers or washers would have to be inserted in between the bellhousing ears and the inner transom plate ears. See:

http://216.37.204.206/Shorts/mercrui...=113&A=39&B=24

for a reference. Drilling would not do anything, or maybe I'm missing something? The fronts seem fine. This problem is at the rear only as I have tried every front height adjustment possible. I don't mean to sound snotty, my writing just sounds that way. I totally appreciate anybodys help on this.

Re: Engine Alignment
 

do you have front and rear motor mounts? Prevous post refers to the motor mounts not the picture you provided.

Re: Engine Alignment
 

Look at the inner transom mount plate, you may be able to loosen it and "realign" it there is a slight amount of clearance in the through holes, this could be where some of the missalignment has come from. But I agree that the boat may not have been set up correcly from the start. My o2

Dave

Re: Engine Alignment
 

I think they are (or were) doing crummy jobs of alignment at MerCruiser from the factory. My Chevy 5.7L mounts same as most other production, bellhousing mount in the rear with two ears, and the a mount on each side of the engine near the front. The two side mounts are adjustable in height, which has not fixed the problem at any setting. Thanks again, and keep the ideas pouring in. I'll try all of them!

Clint

Re: Engine Alignment
 

On the page you linked to, item 14 is a spacer that goes on top of the gimbal housing pad, and the flywheel housing sits on top of that. # 14 is a special double wound lock washer. There normally is a fiber washer that fits around the OD of #14. Spacer #12 sits on top of the flywheel housing

Re: Engine Alignment
 

Oh, BTW- do you have a big boat? to make up for your screen-name? :eek: J/K, you know. :drink:

Re: Engine Alignment
 

I too have an Alpha 1Gen1. I just had the rear motor mounts in the rear replaced. Merc. Has a new way of doing it now. They still use the fiber washers but instead of the double wound lock washer they use a flat washer. I had to have the rubber mounts pressed out of those ears and different ones put in. The Mech. said the old ones let the engine move around too much.

Re: Engine Alignment
 

Mercruiser doesn't align the engines. That is the responsibility of the builder. If the drive won't slide on, then the alignment is totally fubar. Get the alignment tool and check it. The transom assembly holes are drilled oversized for this purpose. Loosen it and you can slide it around a little bit. A rubber mallet works good for this.

Re: Engine Alignment
 

I had the same problem this year when I re-installed my 502. When the "tool" was slid into the coupler it seemed that the rear of the engine was a little bit low. Last year when I checked the alignment it seemed a little low as well but not as much. I ended up making shims out of 1/8" sheet stock and used a hole saw to make the shims fit around the spring. It brought the engine up to perfect alignment. I also adjusted the front mounts a little, too. After I ran it on the lake for the first time I pulled the drive and re-checked the alignment. It was as near perfect as I have ever seen. I have heard of others using shims to get the rear alignment correct. Maybe the inner transom plate moves down a little over time. I don't know for sure if that is what happened but, I do know that without the shims in the rear the tool did not feel right. Good luck.

Re: Engine Alignment
 

The loose holes or slots in the inner plate are just to account for different thickness boat transoms. The inner plate is held in vertical alignment with the outer housing by the center tube from the outer housing going into the inner plate. The rear of the engine is supposed to be a fixed height with no adjustment. I have heard of the mounts breaking down and letting the engine sag in the rear. What you may need to do is align the gimbal bearing first to get the tool to hit the coupler in the center. Then try raising or lowering the front of the engine until the tool will slide all the way in.

Checking the alignment on an Alpha or Bravo is also easier with the "ITS" Bravo alignment tool. It should work with any Bravo or Alpha. It has a removable slide for the gimbal bearing to allow use with or without the ITS extension box. If you remove the slide part of the tool you should be able to slip the tool all the way into the coupler and you should then have gap between diameter of the bar and the gimbal bearing. You can then raise or lower the front of the engine until the bar seems centered in the gimbal bearing. It's much easier than trying to look at grease on the end of a standard alignment tool to tell which way the engine alignment has to move.

Good Luck!

Re: Engine Alignment
 

Thanks. I'm pretty sure I'm going to have to shim it up. I tried every gimbal alignment and front (side) motor mount adjustment possible, and yet the drive only slide on easily when the engine is lifted 2 clicks with a come-a-long. With this many not fitting right, I think the alignment was not right when they tooled up the inner transom plate or the bellhousing.

Clint

Re: Engine Alignment
 

Name is SmallPP because my boat is small compared to all the big money boats everybody else here has. 17' Formula, 1983. Bought it for $1000 on eBay, outdrive came in many milk crates. Was my first outdrive rebuild (Alpha1, Gen1) and it went perfect. Solid and silent as a rock. Current power is factory MerCruiser/GM 4.3L V6 4 barrel Q-Junk (works well actually). It is the only one I have seen with a 4.3L V6 in it. Runs almost 55 stock. Most others have 470 or 3.0L 4 cylinder. I have built up a late model GM Vortec 5.7 to install using Dennis Moore's recommendations on heads (Vortec), cam (Crane something, I forgot the number), roller rocker arms, and Edelbrock Air Gap Vortec intake. I also purchased his aluminum exhaust manifolds, but I'm a bit scared of reversion with them (just because of a larger camshaft than stock).

Would love to buy a Formula 242 with twin 350's. One just sold on eBay for $9000. Was going to buy Cuda's in Florida, but I dragged my butt too long and it sold. I see he misses it already, which tells me they are fun boats.

Re: Engine Alignment
 

I am beginning to wonder if you have the parts assembled correct. The fiber washer is glued on top of the ear on the inner plate. The spiral wound washer is also on top of the inner plate, below the motor mount. The spacer and the larger washer are above the motor mount. Also are you sure that the gimbal bearing is aligned before you try to align the engine? I have installed dozens of Bravo transoms and engines without much trouble unless I was working with plate mounts that were out of alignment.

Re: Engine Alignment
 

I had this attachment made up so that I was absotutely sure that the engines were in alignment.

If the plate doesn't fit flush with the drive opening as shown the engine alignment is off.

The rear mounts can sag and by lowering the front mount the alignment tool will still go in.

I had one engine that for the last few years was just a little off.
I spent 3 hours this year getting it just right.

Re: Engine Alignment
 

You can also use a digital protractor and compare the transom angle to the front of the crank pulley. It should be a 13 deg difference. When I checked one this way I found that the best angle is actually just shy at 12.7 degrees. I noticed that half a degree more or less wouldn't let the tool go in.

I am not sure what you's mean when you say adjust the gimble bearing. Mine just goes inta the housing till it stops against the housing. There is no adjustment. I am having the same problems with the rear mount. 1989 4.3

are you checking the engine aligment with the rear bolts torqued to factory specs??

I actually had the same problem last year with my 2003 fourwinns and a 4.3l mpi, it blew out my coupler and when the tech replaced the engine and did the alignment it was out by almost 3 degrees enough for the front of the engine to be 2 inches higher in the bilge! hence why the coupler blew on a almost brand new boat (about 200hours on it) and it was like that from factory. So proof it does happen.

Old thread, but anyways.... When I bought my boat, it only had 120 hrs. Both couplers where shot. The front mounts where off so much that when I tighten the bolts, the rear of the motor would lift off the rear mount throwing the alignment off. Only way both my drives where installed fom the dealer/factory/rigger/whoever, was the drives where installed, then the mounts where tighted. I had to to install 1/4" spacers at the bottom bolts, then taper to nothing at the top bolts. A fugged up install, and they did it on both motors!