Diving into 5.7 replacement

skargo

skargo

Banned
Joined
Sep 14, 2008
Messages
4,640
Got my GM Performance long block engine in hand, and will start the swap probably Monday. I hope it's ready to splash by Friday :eek:

Any tips are appreciated, as this is my first boat repower.

It's a 1978 Wellcraft Nova 5.7 with an Alpha one Gen one.

Thanks, happy boating!
 
D

dubs283

Vice Admiral
Joined
Jul 27, 2005
Messages
5,091
Re: Diving into 5.7 replacement

place the new long block next to the old bobtail and start swapping parts, cleaning gasket surfaces of course

install new tune-up parts - plugs, wires, cap, rotor, points, filters, etc...

good time to rebuild the carb and if the starter or alternator look gross have them done too

run the new engine on the floor before install to avoid having to pull it again for any issues
 
Don S

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Diving into 5.7 replacement

Pick out a color (Black for Merc.) get some Rustolem paint and paint often. Paint the pan daily along with the timing cover. Keep the timing tab visible. Unless you have closed cooling, take the time to replace ALL of the cooling system core plugs with brass plugs. Gasket are NOT reusable, even for the distributor.
Pay attention to details. When you think you might be forgetting something. You probably are.
Clean and paint the bilge area.
Check everything that is hard to get to with the engine in the boat. Pumps, steering, trim hoses, etc.
New rear mounts, the only way to get to them is with the engine out.
Coupler, just like the motor mounts. How do the splines look.
Run the engine "on the floor" before even thinking about installing it in the boat.
That's a start.

One more thing. New engine = new manifolds and risers.
 
skargo

skargo

Banned
Joined
Sep 14, 2008
Messages
4,640
Re: Diving into 5.7 replacement

New waterpump, check.
Bronze freeze plugs, check(overkill since I have closed cooling.
New manifolds and risers check.
I should replace the rear mounts? I will look into that!
New gaskets check.
New paint check.
We will run it on the stand tomorrow or Sunday, check.
Replacing pretty much all lines and hoses, and will be checking on everything that is accessible when engine is out.

Thanks guys.
 
Don S

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Diving into 5.7 replacement

Bronze freeze plugs, check(overkill since I have closed cooling.
Click to expand...
No need with closed cooling. You didn't mention you had it.
 
mnypitboat

mnypitboat

Lieutenant Junior Grade
Joined
May 31, 2010
Messages
1,091
Re: Diving into 5.7 replacement

You will need an alignment tool to get the outdrive back in. Even if it is a like for like swap, trust me, the mounts are not machined into the blocks in the exacty same place. Replace your Gimbal bearing and all the bellows while you have it all out. Cheap insurance. Otherwise it is pretty straighforward with the advice you already recieved above. Very easy when compared to a modern car engine swap. We had the engine out and back in in about 1 hour. I used parts from another parts engine when I did mine, so it was sitting on the floor ready to drop in, alternator, p/s, etc etc already installed on new engine.

We did not have an alignment tool and I just brought it to a local shop and he installed the outdrive and lined it all up for me, installed my gimbal bearing and bellows all for $100. I figured I would never be doing this again, why buy the tool when this guy was gonna do it so cheap. I went to St Augustine for the weekend while he worked on it. I figured that was a much better use of my time.
 
skargo

skargo

Banned
Joined
Sep 14, 2008
Messages
4,640
Re: Diving into 5.7 replacement

Ummm, filthiest bilge contest entrant? :redface:

268800_10150676696670652_554955651_19291750_7300485_n.jpg
 
J

Jay Gadsby

Cadet
Joined
Jun 26, 2010
Messages
22
Re: Diving into 5.7 replacement

Everything mentioned above= good advice. Take your time, ensure you use the proper torque specs and sequences. I didnt have any issue installing my Alpha One without a tool and it went right in (installed by myself with no helpers in under an hour). Good luck with it all! And be sure to keep an eye on bolts after you run it for the first couple times. Heat cycles can be tricky, especially on a new engine. Learned that the hard way :)
 
45Auto

45Auto

Commander
Joined
May 31, 2002
Messages
2,842
Re: Diving into 5.7 replacement

I didnt have any issue installing my Alpha One without a tool and it went right in (installed by myself with no helpers in under an hour).
Click to expand...

You don't need the alignment tool to install the outdrive. They are usually pretty easy to install even if the alignment is way off.

If you don't align the outdrive, you run a good risk of stripping your coupler in the not-too-distant future, then you get to pull the engine to replace the coupler.

And if you don't align your new one, you get to pull the engine again and again every so often till you get smart enough to use an alignment tool! :)
 
mnypitboat

mnypitboat

Lieutenant Junior Grade
Joined
May 31, 2010
Messages
1,091
Re: Diving into 5.7 replacement

45Auto said:
You don't need the alignment tool to install the outdrive. They are usually pretty easy to install even if the alignment is way off.

If you don't align the outdrive, you run a good risk of stripping your coupler in the not-too-distant future, then you get to pull the engine to replace the coupler.

And if you don't align your new one, you get to pull the engine again and again every so often till you get smart enough to use an alignment tool! :)
Click to expand...

My gimbal bearing seized up while I had the engine out, so that is probably why it didnt go right in. But as you said, if its not aligned, you will cause other issues. Like I said, even though it is small block for small block, the mounting points never seem to be in the same place. My engine sits about 1.5" lower now than it did before. Which created another issue,. I couldnt get my water seperator off when I went to change it at the beginning of the season. I had to lift the engine up some, and install a shorter seperator, which should be fince since I replace it 3 times a year.
 
AZSenza

AZSenza

Chief Petty Officer
Joined
Mar 11, 2008
Messages
521
Re: Diving into 5.7 replacement

What engine did you get, the 330Hp? I'll be in the market soon and thats the one I'm looking at along with an aluminum intake for weight reduction (fresh water only) along with aluminum manifolds and risers.
 
skargo

skargo

Banned
Joined
Sep 14, 2008
Messages
4,640
Re: Diving into 5.7 replacement

AZSenza said:
What engine did you get, the 330Hp? I'll be in the market soon and thats the one I'm looking at along with an aluminum intake for weight reduction (fresh water only) along with aluminum manifolds and risers.
Click to expand...
Nope, just the standard truck engine, basically the same thing that was in there(Mercruiser 260), and it is in and sounds good. I am splashing it tomorrow. Need to get the timing right.

270857_10150686975195652_554955651_19345029_6470000_n.jpg


260377_10150686977070652_554955651_19345050_3694211_n.jpg
 
You must log in or register to reply here.
Top