4.3L Mercruiser Milkshake

[nola mike]

I asked him if it included a module and this was his response…

It had a Mallory points and condenser distributor that I swapped the points out for a Pertronix Electronics ignition kit in. Way more reliable than any Thunderbolt module and if it were ever to fail I can put the points back in and be boating in 10 minutes. I’ll throw in the distributor at no charge.

Sorry for all the questions haha, this whole project has been a big learning curve for me. Would this mean I have everything needed for the ignition side then?

If it includes the pertronix kit then yes.

 

[dubs283]

Dunno why anyone would ditch a solid thunderbolt ignition for a pertronix but people do weird things

Seeing as how tbolt ignition modules are becoming unicorns may be acceptable to take the offered ignition system

 

[Lukey220]

Well everyone the problem was located.. Engine swap time

 

[Rick Stephens]

Yowser.

 

[nola mike]

Is that just rusted through?

 

[Lukey220]

Is that just rusted through?

That’s what it looked like to me! Probably rusted itself thin and it’s first start up in 10 ish years blew the hole open I assume.

 

[tpenfield]

Scales of rust flaking off the cylinder side walls reducing its thickness and eventually the pressure inside the cylinder breaks the weakened area.

First example that I've seen happen, but it certainly can & does. that is one of the reasons why raw water cooled engines in salt water have a limited life span . . . probably 15 years or so.

 

[Lou C]

Interesting. Does look like rust thru rather than freeze damage because the cast iron there looks very thin. My original short block has 20 seasons in salt water on it maybe more but I have been filling the engine with AF with corrosion inhibitors since I’ve owned it for winterization. Wonder how much longer it’ll go lol?
Heads were replaced in 2017 so if I could pick up a reman short block like this one I could just transfer them over…

 

[Lukey220]

Going Wednesday to pick up that 350! Should be a fun boat when it’s all said and done. Still hoping to splash it this year. Has taken me a year and a half so far working weekends to restore this thing so getting antsy!

 

[Lukey220]

Going Wednesday to pick up that 350! Should be a fun boat when it’s all said and done. Still hoping to splash it this year. Has taken me a year and a half so far working weekends to restore this thing so getting antsy!

 

[Scott06]

Looks good. If they engines are similar vintage the coupler should swap over no issue. I did a 4.3=>5.0 swap was able to use most of the peripherals off the 4.3 with exception of exhaust, needed manifolds, riser elbows and down turn elbows to match up with wye pipe. You will need to go up in prop pitch probably 4" or maybe get a different ratio drive . Either way a nice upgrade

 

[Lukey220]

Looks good. If they engines are similar vintage the coupler should swap over no issue. I did a 4.3=>5.0 swap was able to use most of the peripherals off the 4.3 with exception of exhaust, needed manifolds, riser elbows and down turn elbows to match up with wye pipe. You will need to go up in prop pitch probably 4" or maybe get a different ratio drive . Either way a nice upgrade

Appreciate it! The motors are the same year so hoping coupler will be reusable! How big of an upgrade did you find the 5.0 over 4.3?

 

[Scott06]

Appreciate it! The motors are the same year so hoping coupler will be reusable! How big of an upgrade did you find the 5.0 over 4.3?

I bought a handyman's special (sea Ray 200 sport) with a known cracked engine block so I never ran the boat with the 4.3.

I did some calcs basically lb of boat/hp and realized that it would be the same as my old boat (17 ft /3.0 which was lacking) so I put back in the equivalent of the largest engine offered in the boat (5.0/260 hp). If I had to do it again I would just have done a 5.7 and had another 30-40 hp. Bottom line it works great.

What boat are you doing this in ?

 

[Lukey220]

I bought a handyman's special (sea Ray 200 sport) with a known cracked engine block so I never ran the boat with the 4.3.

I did some calcs basically lb of boat/hp and realized that it would be the same as my old boat (17 ft /3.0 which was lacking) so I put back in the equivalent of the largest engine offered in the boat (5.0/260 hp). If I had to do it again I would just have done a 5.7 and had another 30-40 hp. Bottom line it works great.

What boat are you doing this in ?

It’s a 18 ft 1989 Doral Bowrider. Converting it to a fish and ski layout with more of a bias towards fishing. Should haul ass with the 5.7 haha.

 

[Scott Danforth]

Going Wednesday to pick up that 350! Should be a fun boat when it’s all said and done. Still hoping to splash it this year. Has taken me a year and a half so far working weekends to restore this thing so getting antsy!

the V8 looks to be a 1984 or older motor.

what year was the V6?

 

[Lukey220]

I believe 88 but would have to double check when I’m home. He said came out of his 89 boat so just assumed it was an 89 motor. Big changes from 84 to 88/89?

Edit : I’m an idiot and mixed up ads I was looking at… it is indeed an 84.
What issues am I looking at here?

 

[Scott06]

the V8 looks to be a 1984 or older motor.

what year was the V6?

Two piece rear main seal = need a diff coupler

 

[Lou C]

Just another quick question for anyone who knows.. will a Mercruiser 350 bolt up in place of my 4.3? Both late 80’s Motors but the 350 is rebuilt with receipts and looks real clean for a decent deal.

One thing you need to find out is if both are one piece main seal engines. The flywheels are different and a coupler for the 2 piece main seal won’t fit the flywheel for the one piece & vice versa. So find out about that…
Agreed those perimeter bolt valve covers are a clue. Later engines have center bolt valve covers….

 

[Lukey220]

One thing you need to find out is if both are one piece main seal engines. The flywheels are different and a coupler for the 2 piece main seal won’t fit the flywheel for the one piece & vice versa. So find out about that…
Agreed those perimeter bolt valve covers are a clue. Later engines have center bolt valve covers….

Damn… my 4.3l is definitely 1 piece main seal as my bolts are Center on covers.

Huge bummer that it won’t work, thanks for catching that guys! Is there adapters for the couplers or anything to make the swap work or am I SOL?

 

[Lou C]

What size boat are you putting the new engine in?
If its a 17-19 footer then why not just get a late model Vortec 4.3 with a 4bbl carb? That will make the whole thing simpler and cheaper, you will need to use an electric fuel pump and a Vortec intake manifold but other than that it should be an easy swap.
If you have a 20-21' then going to the V8 makes sense, but there are extra costs, exhaust system for one, carb has to be rejetted but most of all is making that 1.81:1 gear ratio work with the V8.
I had the same thoughts with my boat which is a heavy 20' with the 4.3, I'd like to go to the V8, the drive in mine (Cobra) is a 1.62:1 so it might be do-able. If not I have no problem with a Vortec V6 since the fuel economy is quite good for this size boat.