4.3l automotive in a boat??

[medalist1901]

So, I have a boat that I just bought.. Turns out the people that owned it before I did, did not winterize it It is a 1988 starcraft Medalist 1901. It has a small crack in one of the heads, and a crack on the side of the block. The manifolds also have a small crack on the bottom of both of them. I can just weld the cracks shut again, I think.. They dont leak too bad, with it running. Has anybody ever welded a block or a head, or manifold for a crack?? If so, who did it work out?? I also have a few 4.3l chevy engines. Can I put one of these motors in it?? if so what do I have too change besides the alt. starter, and the carb?? Thanks for any help you can give..

Thanks Bryan

 

[Maclin]

Re: 4.3l automotive in a boat??

Get new exhaust manifolds and risers. The exhaust manifolds have two passages, water and exhaust. The crack(s) may not just be external in the manifold, it could be cracked betwen the passages and could let water into the exhaust passage. If this happens then water will enter any cylinder where the exhaust valve is not entirely closed when it shuts down. Then the next time the engine is cranked it will be hydrolocked.


If the boat was run in fresh water then it is due for manifolds at that age anyway. If it was run in salt water it is past due.

As for the block and heads I would follow the advice of a machine shop if I could. The heads could probably be welded but I would go with at least a new block.

 

[bomar76]

Re: 4.3l automotive in a boat??

Your manifolds are junk, replace them and risers.

Welding the heads is a really bad idea, they are junk, if you were gonna keep the block just put some junk yard heads on it.

As for the block, with all the cracks you have found so far, and the ones you haven't discovered (like the ones under the intake manifold)...you are throwing $$$ at a lost cause.

Either buy a long block and and go that route, or buy a junk yard take off from a TRUCK (of the appropriate vintage...you will need one with the mechanical fuel pump boss) and swap out the carb, circ pump, oil pan, fuel pump, fuel lines, distributor, ignition system, starter, alternator, add brass core plugs, etc.

You will still need new mainifolds and risers.

 

[Bondo]

Re: 4.3l automotive in a boat??

Ayuh,....

For some reason,.. You have 2 threads going about the Same Issue, with the Same boat....

I've welded a few blocks,... Some were actually Sucessful.... Most are Not....

I'd go with Bomar's advice,.... The odds of Sucess will be Much Higher...

But,... Before I spent a Penny,...
You should be evaluating the rest of your boat....

After all,.... It's a 1988,+ powered by OMC......

I already know that you Can't buy many of the Parts for the driveline,....

It'll be ashame if you dump abunch of Money into it,+ only discover it to be Rotten,+ devoid of it's Wood as well......

 

[bomar76]

Re: 4.3l automotive in a boat??

I didn't see the other thread, so I had no idea it was an OMC....

With that tidbit of info, I am altering my advice and agreeing w/ Bondo...
unless the rest of that boat is darn near 100% condition, cut your losses and part the thing out or sell it as is.

Repowering and new manifolds are way more than it's worth if it has any other (as in likely rot issues) problems.

 

[medalist1901]

Re: 4.3l automotive in a boat??

well, for the rest on the boat the fiberglass is in great condition, there not 1 nick or scratch under or on the sides. The int. is a little rough, but I can do redo all of that, that is my second hobby. The outdrive goes in and out of gear good. The oil in the outdrive is nice and clean. The only issue is they didnt winterize the darn thing, and left it out in the weather, w/o a cover. I have already replaced the plywood floor and carpet, That I had layin around the shop. I just need to get this new engine in it and get it out on the water and see if it all works out Thanks Again Bryan

 

[Don S]

Re: 4.3l automotive in a boat??

I just need to get this new engine in it and get it out on the water and see if it all works out

You need to get the boat OUT of the water, then remove the outdrive, THEN you remove the engine and put the new one back in. Then yo align the engine with an alignment bar, and only then do you reinstall the drive.
What you suggest is going to turn into an expensive hobby of pulling the engine and replacing couplers because the engine isn't aligned properly.
Yes, some things on boats requier special equipment and knowledge.

 

[medalist1901]

Re: 4.3l automotive in a boat??

so you have to take the outdrive off to put the engine in?? can I take the boat to a boat shop and have them align it?? See, this if the first boat i have owned. I am a auto machanic, but I know the boat is different. in a car (automatic) the flywheel is bolted to the crank and the t. converter is bolted to the flywheel too turn the flywheel. To take the engine out you just unbolt the t. converter from the flywheel. Now, in a boat what does the flywheel bolt to?? That is the only stoping me from pulling the engine out.

 

[Gary H NC]

Re: 4.3l automotive in a boat??

Yes the drive must come off and yes it must be aligned before it is put back on...
Man,you really need a manual!
Take Don's advice and it will save you huge headaches.
Is this boat still in the water? Time to trailer it to a shop.

The flywheel and drive are connected thru the splines of the engine coupler.

 

[mylesm260]

Re: 4.3l automotive in a boat??

You need to get the boat OUT of the water, then remove the outdrive, THEN you remove the engine and put the new one back in. Then yo align the engine with an alignment bar, and only then do you reinstall the drive.
What you suggest is going to turn into an expensive hobby of pulling the engine and replacing couplers because the engine isn't aligned properly.
Yes, some things on boats requier special equipment and knowledge.

I'm gona go ahead and put up my hand here.

Yeah, I did that, I did exactly that. And now have have a new coupler, and I know how to replace a gimbal bearing and align a motor. =)

On a side note:
I welded both my cracked manifolds with my mig welder and they've worked perfectly for 2 seaons.

Each had about an 8" crack, and an offset, I used a hammer to bend the offset back, I used my angler grinder and made a big V in the crack, then I used my mig welder and filled in the V, they've worked perfectly thus far, not a single leak, Oh yeah and I painted them with POR 15


I'm using a 2001 chev astro motor in my boat, and with a new prop, I went from 50 or so MPH to 63 on the GPS.

Going from the old odd-fire, old scholl heads, 2 barral carbed setup to the even fire, vortec, EFI setup made a HUGE difference in power and fuel economy.

In terms of going from an automotive mechanic to a marine one, you've done the right thing, you came here first.

The drive's are pretty simple, get yourself a manual and just make sure you read before you do.

Removing the engine:

1. Remove the drive (usually 6 bolts, pretty simple, remember always use new gaskets when reassembling)

2. Undo the side and rear engine mounts.

3. The obvious (fuel, electrical, cooling)

4. use a shop crane and pull the engine.



Installing the engine is the reverse except:

Before you reinstall the drive, you use an alignment tool and align the engine. Do it carefully, if you don't, you will strip your coupler splines like I did.

 

[bomar76]

Re: 4.3l automotive in a boat??

Going from the old odd-fire, old scholl heads, 2 barral carbed setup to the even fire, vortec, EFI setup made a HUGE difference in power and fuel economy.

Let me guess...
you used the automotive EFI system from the donor vehcle?
Which is not:
1. Safe
2. Legal
or
3. Suited
for use in a boat.

 

[medalist1901]

Re: 4.3l automotive in a boat??

yeah, i got a manual from the library, they had one there!! i have not looked at it yet dont have time tonight. im glad. Yes, the is out of the water, I dont know how long but the year on the sticker on the side of the boat says 04. that was a long time ago!! Im glad I was told the motor needs to be aligned, man I would of messed some stuff up, unless they tell you that in the manual. As far as my manifolds, I welded them and put that 48 hr cure JB Weld on them for a little extra help. i ran the old engine last night for no reason, This morning is when I pulled the manifolds, the runners looked to be dry, and no traces of water has been in the exhaust ports in the manifold and in the exhaust valve port. I hope the manifolds are still good, cause I dont want too spend $700-1000. on a new set. will see!!

 

[mylesm260]

Re: 4.3l automotive in a boat??

Let me guess...
you used the automotive EFI system from the donor vehcle?
Which is not:
1. Safe
2. Legal
or
3. Suited
for use in a boat.

I did, and I've been a part of many threads on this forum on the subject.

Bottom line. USCG regs do not even mention EFI, they were writen in the age of carbs.

AND the TBI part numbers are the exact same between marine and automotive. Check the archives for "what's the difference between an automotive and marine tbi unit" or something like that....

So seing as how the CG regs don't mention efi, it pretty much IS legal.

And seing as how EFI is inherinetly safer that carbs, it's safer aswell. IF there was a problem with the EFI system, the owners of S-10's, sonomas, safaris, astros, blazers, brazada's, and s1500 pickups would have all had the same issues.

Yes if there's a fire, it's much worse on a boat (explosion) but fires happen in cars and trucks too, and seeing as how those 4.3's were used in millions of vehicles, I'm pretty sure their EFI systems are safe.


Suited? How do you figure? I have a similar cam profile to marine, and my EFI system is delivering optimum fuel for each RPM range? How would a marine EFI system be any different that what I'm running? And before you say tunning, I should let you know that I've actually built and tuned a few EFI computers in my time (megasquirts on 450 HP datsun L28ET's)


My boat's plane time and top speed is just as good as a brand new 228 HP 4.3 GM marine engine. And I believe I have one of the fasted v6 powered boats on this forum. (another older thread in the gerneal boating forums). Go ask the v6 guys how many of them can get 63 MPH on a GPS and still get on plane quickly with 10 people in their boat.


http://forums.iboats.com/showthread.php?t=276549&highlight=how+fast+v6&page=3

 

[medalist1901]

Re: 4.3l automotive in a boat??

mylesm260, do you have the wireing, and the computer out of the van in you boat?? or do you have the marine EFI wireing and computer in it??

 

[bomar76]

Re: 4.3l automotive in a boat??

I did, and I've been a part of many threads on this forum on the subject.

Bottom line. USCG regs do not even mention EFI, they were writen in the age of carbs.

Yack, yack, yack....

Yeah, I remember those threads well....figured you would chime in.
Few agreed with you, and I still stand by my view.

 

[medalist1901]

Re: 4.3l automotive in a boat??

hold on, see I work on automotive 4.3 Vortec's. I think the injection are diff. in a marine. In the trucks the Vortec engine, there is a spider injector in the upper intake. On the marine Vortec engine it is TBI. am i correct on this??

 

[180shabah]

Re: 4.3l automotive in a boat??

Depends on whether the marine engine was TBI or MPI.

 

[mylesm260]

Re: 4.3l automotive in a boat??

To answer you questions:

1. I made a custom wiring harness, and am using the van ECU
2. You are correct regarding marine VS automotive

The TBI setups are the same from what I can tell but the multiport setups are vastly different.

The automotive multipoint setup is the "popit spider" setup.. Those who are familiar with them will know exactly what I'm talking about

The marine multipoint setup is your standard BOSH setup, with 2 fuel rails, and 6 bosh fuel injectors.

Logically the two systems are the same.... But they are put together much differently.


I am running the "automotive popit spider multipoint" setup from an AWD astro (200 HP in automotive application, like 220 in a boat)

Yes, I realize that this setup was never used on a boat, but I still believe it to be safe. In fact in many ways it's safter than the marine multipoint setup, because I have no fuel rails and my FPR is built in to the injection system which is inside the manifold... Any fuel leaks, it leaks directly into the manifold, not externally like it would on the marine setup.

 

[dan t.]

Re: 4.3l automotive in a boat??

good to see someone doing a little expermenting, far to many marine purests out there

 

[medalist1901]

Re: 4.3l automotive in a boat??

mylesm260, I would like to see some pic's of that if you have some. I could see where that would be safer than the marine setup, its like a sealed system. I would thing its a lot safer than the carb's that are used on sooo many boats. I do have one of these engines. It came out of 2001 Chevy blazer, with only 32,000 miles. I just have to figure out the wireing issues. the o2 sensores are the least of the wories. You just need a few resistors too handle that, let me know if you have any pic!!