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conversion parts for 350 chevy using the 351 trans

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Category: General Correct Craft Discussion
Forum Name: General Discussion
Forum Discription: Anything Correct Craft
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=51937
Printed Date: May-02-2025 at 11:27pm


Topic: conversion parts for 350 chevy using the 351 trans
Posted By: rippbj
Subject: conversion parts for 350 chevy using the 351 trans
Date Posted: April-30-2025 at 9:51am
Hi,
     I have a Mercruiser 350 chevy engine and a 1989 Ski Nautique with a blown engine.  Does anyone have any conversion parts or source to marry the 350 with the 351 Windsor transmission?  Thanks!


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Brad Ripp
Pearl River, LA
88 Barefoot Nautique



Replies:
Posted By: KENO
Date Posted: April-30-2025 at 7:27pm
Is this a Mercruiser from an inboard-outboard that you're working with?

The biggest thing you'll need is a bellhousing to mate the Chevy engine to your 1989 PCM Model 40A transmission.

There are plenty of them out there new or used, (same mounting bolt pattern as a Borg Warner 71c,) but........you need to know what this Mercruiser engine has for a flywheel. It'll be either 168 teeth (14 inch diameter) or 153 teeth (about 12 3/4 inch diameter

Your starter location also comes into play. You might have a bottom mounted front entry starter (just like the automotive location) or a top mount rear entry starter on your engine.

With that info you can come up with a bellhousing that'll work. Some of the bellhousings will work with either starter and some only work with one style or the other.

It won't matter if the bellhousing is from a Mercruiser 350 inboard, A PCM Chevy, an Indmar Chevy or a handful of other brands as long as it will adapt the engine to an inboard style transmission

You'll also need a damper plate to bolt to the flywheel, but the good news is that the one on your Ford  now for the PCM 40A transmission will also fit the Chevy flywheel. There are multiple mounting holes that can be used. 

If yours isn't in good shape, now would be the time to replace it. The only way to get one for the 40A is thru PCM and it gets kinda pricey.

There are plenty of inboards that used Mercruiser inboard engines in the 80's and 90's so parts should be relatively easy to find.

I'll guess that your starter is in the automotive location but won't guess which flywheel you have  Wink

 



Posted By: TRBenj
Date Posted: May-01-2025 at 10:04am
You’ll also need the conversion mounts that PCM sells in order to relocate the Chevy mounts to the Ford footprint (SkiDIM sells them). Not all boats require these but the 89 with the tabbed engine cradle will.


Posted By: rippbj
Date Posted: May-01-2025 at 10:16am
Keno,
    Thank you for the reply!  The Mercruiser came out of an inboard boat.  I'll measure the flywheel and reply and then see what is next.
Thanks!
Brad



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Brad Ripp
Pearl River, LA
88 Barefoot Nautique


Posted By: rippbj
Date Posted: May-01-2025 at 10:18am
Thanks!  I had emailed SkiDM and Jody Seal replied with those mount part numbers.   I've used them several times before and they go above and beyond! Thanks for the reply and info!
Brad



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Brad Ripp
Pearl River, LA
88 Barefoot Nautique


Posted By: Fl Inboards
Date Posted: May-02-2025 at 12:31pm
Glad you found the site. like we discussed your proposition is like a puzzle. you just have to find all the right pieces. the 89 was the first year of the power plus 80A transmission so your engine frame is going to be configured for that transmission. installing a left hand velvet drive can be done but the boat wont act right and re-engineering the engine frame is over thinking. i am sure you can find a used 80a and the reduction mounts . add the adapter engine mounts and your a go.. ill go first i have a used 40a, a GM bell housing (Indmar)(top or bottom mount starter) and a 40 damper plate (new) $850.00 plus shipping. you will need reduction mounts, a cooler and a set of oil lines..
i know of a few other 40A used units for sale also . a fella who frequents this site north of Montgomery has a few 40A also (Zulke)


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Hobby Boats can be expensive when the hobbyist is limited on their own skill and expertise.




1993 Shamrock "fat" 20. 2008 Nautique 196 5.0


Posted By: rippbj
Date Posted: May-02-2025 at 1:01pm
Thank you for the reply.  From the previous posts, I'm not quite sure I know what I need yet.  It sounds like someone is saying that if I have a Mercruiser inboard engine, that it will fit the existing transmission in the 1989 Ski Nautique?  Or did I misunderstand that?  I'm going to post pics of my engine to his reply.  If it winds up that I need what you are offering, that's a good possibility!  

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Brad Ripp
Pearl River, LA
88 Barefoot Nautique


Posted By: wayoutthere
Date Posted: May-02-2025 at 3:38pm
You need to post good pictures of your existing engine and transmission then post pictures of the engine you want to install.
Establishing photo, get the whole engine and trans that is in the boat, then move in and get all other pertinant photos related to your questions. Do the same for the engine you want to instal.

These guys will get you straightened out and back on the water.
Good luck with yoir project


Posted By: rippbj
Date Posted: May-02-2025 at 3:56pm
Here are pictures of the Mercruiser going in and the existing transmission in the boat.  What do I need to marry these or will they bolt together as is?  Thank you!
Brad
 


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Brad Ripp
Pearl River, LA
88 Barefoot Nautique


Posted By: KENO
Date Posted: May-02-2025 at 4:29pm
Now if you had said a few more things in your first post, this would have been a whole lot easier. Wink

Looks to me like you have the Mercruiser engine, complete with it's starter  and flywheel and bellhousing.

So....you don't have to look for much of anything to mate the PCM 40A to the Mercruiser bellhousing.

The bolt pattern on the Mercruiser bellhousing and the PCM bellhousing on you Ford are the same on the flange that the transmission bolts to.

Just so you understand.....You don't need a new bellhousing.

You do need to take the bellhousing off of both engines and take the damper plate off of the Ford and install it on the Chevy flywheel. It'll bolt on.  You don't even have to remove the flywheel.

If you want to reuse the used PCM  damper plate or buy a new one, that's up to you.

Then you put the Mercruiser bellhousing back on the Chevy.

And then......you install the PCM 40A on the bellhousing.

You may have to mix and match mounting bolts and studs from the PCM bellhousing and the Mercruiser bellhousing

Now you have an engine and transmission all hooked to each other, ready to install into the boat.

What you do with engine mounts already got mentioned

You'll have to figure your exhaust setup to go from the 2 Mercruiser exhaust manifolds to one 4 inch outlet at the transom

You'll also have to go from 1 inch ID hose at the hull intake to 1 1/4 inch hose before you get to the raw water pump. Probably easiest to go 1 inch to the transmission cooler and then after the cooler outlet use a 1 to 1 1/4 barbed fitting to have 1 1/4 inch hose to the raw water pump.

Mounting the bracket for the shift linkage may be straightforward or may take a little creativity. 

If you have them both out of the boat and do the work, it'll be easier mating them together and then put the engine and transmission in the boat together.




Posted By: wayoutthere
Date Posted: May-02-2025 at 5:18pm
See ! Pictures, always post pictures.

Heres a link to point you towards the 2 into 1 exhaust Keno mentioned.

https://www.correctcraftfan.com/forum/forum_posts.asp?TID=51888&title=hull-hugger-muffler

Could someone fix the link thank you


Posted By: rippbj
Date Posted: May-02-2025 at 5:27pm
Thanks!  The link worked.



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Brad Ripp
Pearl River, LA
88 Barefoot Nautique


Posted By: rippbj
Date Posted: May-02-2025 at 5:28pm
Thanks!



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Brad Ripp
Pearl River, LA
88 Barefoot Nautique


Posted By: rippbj
Date Posted: May-02-2025 at 5:29pm
Thanks

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Brad Ripp
Pearl River, LA
88 Barefoot Nautique



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