Qs for those who've updated their Merc-1 outdrive to Alpha 1

[barato2]

i've been sawing on my transom
all the live long day
i've been sawing on my transom
just to pass the time away

i'm about to enlarge the hole in transom for the Alpha 1 and, to be honest, the idea of taking a saw to my transom scares the carp out of me.

i have good pics and tracings (from inside and outside) of the hole in donorboat transom.

1. any pitfalls i should watch out for, or stuff i need to be aware of?

2. what did you use to cut out the hole? transom is thick but barely do-able for jigsaw, i don't think sawzall is accurate enough?

3. the inner cutout for the alpha 1 has recesses on each side for steering arm clearance. how did you do those? big carbide burr on a die grinder, or what?

thanks!

 

[mkast]

Re: Qs for those who've updated their Merc-1 outdrive to Alpha 1

Are you familiar with what is called the "X" dimension?

 

[barato2]

Re: Qs for those who've updated their Merc-1 outdrive to Alpha 1

never heard the term. but it sounds like either something from an old Star Trek episode, or else where my flashlights, tire gauges, tape measures and individual socks go to hide from me.

 

[KellyC]

Re: Qs for those who've updated their Merc-1 outdrive to Alpha 1

Well I was under the impression that the pre alpha's were the same as the alpha's as for the hole. Now I am wondering what needs to be done as well. WELL CARP MAN

 

[QC]

Re: Qs for those who've updated their Merc-1 outdrive to Alpha 1

never heard the term. but it sounds like either something from an old Star Trek episode, or else where my flashlights, tire gauges, tape measures and individual socks go to hide from me.

LOL I am going to move this to the Mercruiser section. You'll get a tutorial on X dimension and a more focused response on your question there. Good luck!!! I guess that's good luck for the project, and finding your socks there

 

[Bondo]

Re: Qs for those who've updated their Merc-1 outdrive to Alpha 1

Qs for those who've updated their Merc-1 outdrive to Alpha 1

Ayuh,... With the exception of drilling 2 more 5/8" holes,...
The transom cut-out for the Mod. 1, 'n the Alpha 1, 'n the Alpha 1, Gen.II, are All the Same....

The Gen.II has the 2 extra holes at the top...
Some of the really Old Mod. 1s have the hole spacing abit off, but the key-hole is the same....

 

[Don S]

Re: Qs for those who've updated their Merc-1 outdrive to Alpha 1

The location of the cutout for the drive is deterimined by transom angle. The X dimension is the centerline of the crankshaft. It has to be located in the proper place so the outdrives cavitation plate sits in the right place. Like putting an outboard at the proper height.
Problem is you are going THROUGH the transom with a big hole, you cut it wrong, then you redo the transom.
Having said that, what model transom shield, engine are you using. Including year if you know it.
If you can find a serial number on the transom shield, that would be fantastic.

 

[barato2]

Re: Qs for those who've updated their Merc-1 outdrive to Alpha 1

Don, not sure what part the "transom shield" is. is this part of the outdrive/gimbal housing, or are you talking about the boat itself? the good news is that since boat is tin, transom replacement is not too horrid if i screw up....pretty commonly required chore when restoring old Starcrafts.

boat is a 1964 Starchief originally equipped with Mercruiser 120 and Merc-1 outdrive, now with the extra added attraction of one jug so rusted & seized that it looks like a pot of menudo cooking with the head off. drivetrain going in is a Mercruiser 3.0LX and alpha-1 outdrive, pulled from a 1993 Galaxy ski boat with 600 hrs of fresh water use and great compression & oil pressure.

so it looks like i should ideally re-hang the Merc-1 temporarily and measure how far below bottom of hull the prop centerline is, then shoot for same distance on new outdrive? i may not do this since the old gimbal housing is already out of boat. or should i get new motor onto mounts before doing gimbal housing? is the distance in Q roughly the same between the Merc-1 and the alpha 1? i may try instead hanging the new gimbal housing to see if it mates with existing holes (i know Bondo is rarely wrong and he's answered a # of my other Qs over the years) and compare the distance on the two ODs from input driveshaft to prop centerline. i'll do some homework on this and come back with the results.

thanks for taking the time to answer. this will possibly be the last boat i buy and i want to get this right.

 

[Bondo]

Re: Qs for those who've updated their Merc-1 outdrive to Alpha 1

and compare the distance on the two ODs from input driveshaft to prop centerline.

Ayuh,... The holes are still in the hull, Right,...

Line the new assembley up to the bottom holes of the old, 'n the X dimension will be exactly where it was when ya started....

 

[KellyC]

Re: Qs for those who've updated their Merc-1 outdrive to Alpha 1

Bond-o and Don S thank you very much for the information that you both provided. I was actually in a little bit of a panic for a bit when I heard that the 2 outdrives were not the same. But from the sounds of it they are close enough to do the job and just have to drill some new top holes if I understand this all correctly. Thanks again guys.

 

[Don S]

Re: Qs for those who've updated their Merc-1 outdrive to Alpha 1

not sure what part the "transom shield" is.

Just so we know what each other is saying, here are a couple of pictures. It almost sounds like what you are calling an outdrive is actually everything on the back of the boat.

 

[achris]

Re: Qs for those who've updated their Merc-1 outdrive to Alpha 1

Barato2,

Don's an old Volvo man from way back and hasn't updated his terminologies to include Mercruiser nomenclature. What he's calling 'Transom shield' is, in Merc parlance, the gimbal housing.

Bondo hasn't changed an early MC1 out for a while and has forgotten that when Merc introduced the gimbal ring mounted trim senders, the cutout increased in width, a little. Something like 1/2". Also 2 of the mounting stud holes need to be filled and redrilled. I can't remember whether they go up or down, but it's only by about an inch.

As for the 'X' dimension, as long as you use the bottom mounting holes that will be the same for both gimbal housings....

The angled cutouts at the top for the steering arm are created by using a hole saw and running it in at 45 degrees.

HTH.

Chris......

 

[KellyC]

Re: Qs for those who've updated their Merc-1 outdrive to Alpha 1

You are right in that I was talking about everything on the back of the boat Don S. I have all the old gimble bearing assy out as of now. I am looking at a boat with a I6 and an alpha 1 gen 1 on it to replace what I currently have as it is pretty much shot. Thanks again for your help here.

achris thanks for the replay that you added as well, it will be a lot of help when this does come together. I got my 22 ft islander very cheap and that is why I am doing this. The engine is even good but was thinking that the I6 would be better for this boat and the newer outdrive as well. Thanks again.

 

[jasoutside]

Re: Qs for those who've updated their Merc-1 outdrive to Alpha 1

I'm thinking Chris is right on the keyhole being just a little bigger than the MC1/pre Alpha. Seems like I have seen other guys have to deal with that.

For my keyhole cutout I actually used a spec paper copy of a Volvo cutout (same as the Alpha). It was one that Don had posted back in the day, I found it when I was doing a bit of research last year (thanks again Don). I can't quite find the link at the moment - I bet Don might be able to post a link real quick.

You can just take a copy of that and blow it up to the correct size. On mine I used it in combination with my scrapped out glasser transom, laid it out the lines on my transom, and cut away. That would be just about the same process for your transom too, for the most part. (except you won't need to deal with the X Dimension like I had to)

For the angle hole cuts...

I actually cut those first as there is still material available for the bit to grab onto. I then just used a hand file to clean it up.

I hope that all makes sense!

 

[Don S]

Re: Qs for those who've updated their Merc-1 outdrive to Alpha 1

here is the cutout template for the Volvo drive.

http://www.4shared.com/document/tCGrNJY4/SX_Transom_shield_cutout_templ.html?dirPwdVerified=818cbd4e

What you really need to do is go to your local Mercruiser dealer and have him order you a paper template for the Alpha drive. Less than 5 bucks and you can do it right.

 

[jasoutside]

Re: Qs for those who've updated their Merc-1 outdrive to Alpha 1

I think I remember one of my local dealers less than willing to talk about that paper copy (he really wanted to talk to me about a new driveline at $6500) and the other being a bit confused about what I was asking for and ultimately wanting like $30 for it, bummer.

At any rate...

barato/kelly - I believe you both are taking those Alpha 1's out of old hulls, right? If you are there is your template right there, eh!

Cheers

 

[Bondo]

Re: Qs for those who've updated their Merc-1 outdrive to Alpha 1

I am looking at a boat with a I6 and an alpha 1 gen 1 on it to replace what I currently have

Ayuh,... The I-6 was Never used with the Alpha 1 drive,....
It's just a newer vintage/ model of the Mod. 1 drive....

Still a Pre-Alpha though...

 

[barato2]

Re: Qs for those who've updated their Merc-1 outdrive to Alpha 1

OK, i went out last night and measured* and test fitted, and i think i have some answers.
1. short version is YES, you will definitely need to cut out more material at bottom of keyhole. it looks like it will need to be cut downward another inch or so and widened at bottom, to clear protrusions on the Alpha 1 near where the TnT lines pass through gimbal housing.

2. distance from the centerline of driveshaft to centerline of prop axis is 21.75" on the Merc-1 outdrive leg; on the Alpha 1, it's 22.5". so it sounds like you'd need to move things up 3/4" if you want to keep the prop at exactly same distance below bottom of hull

3. of the 8 studs that hold gimbal housing to transom, the lower four studs on gimbal housing line up perfectly with the transom holes from the Merc-1; the four upper ones will need to be redrilled. the four central studs around the driveshaft area are same spacing as to width on both new and old gimbal housings, but the vertical spacing between them is about 9/16" more on the Alpha 1. so it seems if you aligned new gimbal housing on upper pair of these 4 central transom holes, it would mean you'd have to redrill the 3 other pairs of holes, but this would move the gimbal housing up enough that your prop centerline would be within 3/16" of where the old one was. SO....

4. the Q becomes whether to line up the new gimbal housing up on the lower four transom holes (which i suspect is correct), or on the third pair of holes as you go up (which looks like it would keep prop height about the same). i think to get this answer, i need to measure the distance from each set of bolt holes to where the driveshaft centerline would be (forgot to do this last night). i'll do this tonight or this weekend and report back.

* CAVEAT: these measurements were done with the very accurate eyeball-and-tape-measure method so don't go bettin your first-born on them, and check my #s before you cut or drill

i did trace the templates from donor hull onto desk-calendar cardboard. so it sounds like there's another $5-30 i saved by buying a complete donor boat....

Chris, thanks for the hole saw idea! altho it looks like i may not have to cut it any bigger at the top near steering arm area.

on the I6, remember that it's essentially the 4 cyl with 2 extra cylinders....or, more accurately, Chevy made the Chevy II four used for the Mercruiser block by lopping two cylinders off their old Stovebolt six. so the bellhousing bolt patterns should be the same. just think about whether you want to eat up more of your limited cockpit floor with bigger doghouse.

 

[achris]

Re: Qs for those who've updated their Merc-1 outdrive to Alpha 1

OK, i went out last night and measured* and test fitted, and i think i have some answers.
1. short version is YES, you will definitely need to cut out more material at bottom of keyhole. it looks like it will need to be cut downward another inch or so and widened at bottom, to clear protrusions on the Alpha 1 near where the TnT lines pass through gimbal housing.

2. distance from the centerline of driveshaft to centerline of prop axis is 21.75" on the Merc-1 outdrive leg; on the Alpha 1, it's 22.5". so it sounds like you'd need to move things up 3/4" if you want to keep the prop at exactly same distance below bottom of hull

3. of the 8 studs that hold gimbal housing to transom, the lower four studs on gimbal housing line up perfectly with the transom holes from the Merc-1; the four upper ones will need to be redrilled. the four central studs around the driveshaft area are same spacing as to width on both new and old gimbal housings, but the vertical spacing between them is about 9/16" more on the Alpha 1. so it seems if you aligned new gimbal housing on upper pair of these 4 central transom holes, it would mean you'd have to redrill the 3 other pairs of holes, but this would move the gimbal housing up enough that your prop centerline would be within 3/16" of where the old one was. SO....

4. the Q becomes whether to line up the new gimbal housing up on the lower four transom holes (which i suspect is correct), or on the third pair of holes as you go up (which looks like it would keep prop height about the same). i think to get this answer, i need to measure the distance from each set of bolt holes to where the driveshaft centerline would be (forgot to do this last night). i'll do this tonight or this weekend and report back.

* CAVEAT: these measurements were done with the very accurate eyeball-and-tape-measure method so don't go bettin your first-born on them, and check my #s before you cut or drill

i did trace the templates from donor hull onto desk-calendar cardboard. so it sounds like there's another $5-30 i saved by buying a complete donor boat....

Chris, thanks for the hole saw idea! altho it looks like i may not have to cut it any bigger at the top near steering arm area.

on the I6, remember that it's essentially the 4 cyl with 2 extra cylinders....or, more accurately, Chevy made the Chevy II four used for the Mercruiser block by lopping two cylinders off their old Stovebolt six. so the bellhousing bolt patterns should be the same. just think about whether you want to eat up more of your limited cockpit floor with bigger doghouse.

OK.. don't go cutting the BOTTOM of the keyhole to 'deepen' it. Use the bottom pair of mounting studs as your reference point. You'll need to fill the pair of holes in the transom that were the third ones up and redrill them. If you have a pair of studs at the very top, you'll also need to drill holes for them. You shouldn't need to change anything about the steering arm clearance cutouts. If it was done right for the early one, it will be right for the Alpha. You may need to 'flatten out' the bottom of the keyhole to accommodate the Alpha gimbal housing. It's slightly 'beefier' in that area and some of the old cutouts were not generous there.. The bottom of the cutout should be pretty close to parallel with the bottom of the hull. If it's square to the transom, the housing will hang up on it when you try to fit it.

A couple of suggestions. Use a new seal on the gimbal housing, and I put a very thin smear of silicon sealant on the outside of the hull. I also change the mild steel nyloc nuts and washers supplied for the mounting studs to stainless steel. It's easy to do now, and when you need to pull it off again, the nuts will just come straight off instead of you spending days with a cold chisel and knocking you knuckles and hands about....

Good luck,

Chris........

A picture speaks a thousand words...

 

[barato2]

Re: Qs for those who've updated their Merc-1 outdrive to Alpha 1

Chris, thanks for input, and for taking the time to write all that and label/post the pic.

your photo nicely illustrates what i was trying to describe. and very good point on keeping my cutout parallel to bottom of hull.

i do still think i'll need to cut the keyhole slightly bigger, but i was going to drill the stud holes first and THEN see if i can get away with existing cutout. this is definitely a "measure five times, cut once" item.

all seals and bellows are being replaced, but i will use some 4200 on the main seal between gimbal housing and transom. yah, i love stainless (and the Ace Hardware man loves ME when i show up at cash register with a bunch of it....) and that's a very good point on the nuts as this boat will be mostly saltwater boat....and yeah, i know i need to then use anti-seize to prevent dissimilar-metal galling between the mild-steel studs and stainless nuts.