4.3 rebuild ?'s

[ssleeper94]

I have a 4.3 in my starcraft that cracked over winter. I have a running 4.3 out of an old blazer just sitting in my garage. I plan on putting the car motor in the boat. I know the cams are different and the freeze plugs need to be swapped, but I want to put new bearing and rings in the motor. My question is there marine specific rebuild kits and are there any advantage to running them over regular rebuild kit
Thanks
Brian

 

[Fishermark]

Re: 4.3 rebuild ?'s

My question is there marine specific rebuild kits and are there any advantage to running them over regular rebuild kit
Thanks
Brian

Go with FelPro and the composite head gaskets - there are no advantages of a marine kit otherwise.

 

[ssleeper94]

Re: 4.3 rebuild ?'s

I forgot to ask, whats different between a marine head and a auto head

 

[Fishermark]

Re: 4.3 rebuild ?'s

Nothing.

 

[ssleeper94]

Re: 4.3 rebuild ?'s

i mean valvetrain wise

 

[mciaio]

Re: 4.3 rebuild ?'s

I routinely use auto parts for my 5.7. They only thing I use specifically for marine are engine electrical parts, starters, alternators, freeze plugs and head gaskets.

When I did my 5.7 I used auto gaskets for everything except the head gaskets and exhaust elbow gaskets. Head gaskets are stainless steel.
Most other internal parts are the same, although most of the time I find them to be better than production inetrnal parts to get higher performance the boat needs. A boat engine runs all day long in higher rpm ranges where a car stays low. This requires stronger rotating parts; the the head are identical as are the valve parts. Cams are a different grind to produce more torque.

 

[Fishermark]

Re: 4.3 rebuild ?'s

i mean valvetrain wise

I did too.

 

[Bondo]

Re: 4.3 rebuild ?'s

Originally Posted by ssleeper94
i mean valvetrain wise
--------------------------------------------------

I did too.

Ayuh,... 'n I agree....

 

[Rustychain]

Re: 4.3 rebuild ?'s

I have a 4.3 in my starcraft that cracked over winter. I have a running 4.3 out of an old blazer just sitting in my garage. I plan on putting the car motor in the boat. I know the cams are different and the freeze plugs need to be swapped, but I want to put new bearing and rings in the motor. My question is there marine specific rebuild kits and are there any advantage to running them over regular rebuild kit
Thanks
Brian

What year is the "old blazer motor"? If it is after 1993, you have a few more things to look at regarding pistons especially.
Whatever you do, keep the rotating group (crankshaft, camshaft, balance shaft, piston rods) all together as a set.
If you can spend some money, move the rotating group from the boat motor to the blazer motor, except for pistons. Have new 0.030 over pistons put on the boats rods, and have the blazer block bored 0.030 over. Have the machine shop mic the rods, crank and block to get the right bearings.

 

[ssleeper94]

Re: 4.3 rebuild ?'s

it is a pre 93 motor

 

[Bondo]

Re: 4.3 rebuild ?'s

If you can spend some money, move the rotating group from the boat motor to the blazer motor, except for pistons.

Ayuh,... Why swap the rotating assembley,..??
They're the Same,+ it's already mated to the blazer block....
Just rebuild the blazer motor, to marine Specs...

 

[Rustychain]

Re: 4.3 rebuild ?'s

Ayuh,...
They're the Same...

All 4.3's are not "the same". There are dozens of different combinations on cranks, rods, & pistons. 4.3L's originally built for trucks, vans, and boats were built "heavy duty" and 4.3's originally put into S-10 blazers might be heavy duty or "light duty", depending on rated HP in the year they were built. Differences between heavy and light duty is in pistons, rods, crankshaft, heads. Keeping the complete rotating group from the original boat engine is the easiest way to be sure you have the heavy duty parts without doing alot of research.
Any 4.3 is "the same" in that they all will bolt in, start, run, and move the boat off the dock. But if you want it to last for a long time, and not produce strange noise & vibrations, there are alot of details to watch out for. Here's a good starting point for more info..
http://www.enginebuildermag.com/Article/2427/rebuilding_the_new_chevy_262.aspx

 

[Bondo]

Re: 4.3 rebuild ?'s

All 4.3's are not "the same". There are dozens of different combinations on cranks, rods, & pistons. 4.3L's originally built for trucks, vans, and boats were built "heavy duty" and 4.3's originally put into S-10 blazers might be heavy duty or "light duty", depending on rated HP in the year they were built. Differences between heavy and light duty is in pistons, rods, crankshaft, heads. Keeping the complete rotating group from the original boat engine is the easiest way to be sure you have the heavy duty parts without doing alot of research.
Any 4.3 is "the same" in that they all will bolt in, start, run, and move the boat off the dock. But if you want it to last for a long time, and not produce strange noise & vibrations, there are alot of details to watch out for. Here's a good starting point for more info..
http://www.enginebuildermag.com/Article/2427/rebuilding_the_new_chevy_262.aspx

Ayuh,... I'll Agree that ALL 4.3ls are Not the Same, as there's been Many changes during it's run...
But,...
If the Vintage is kept the Same...
The Motors will be the interchangable...

The part I hi-lighted about the Heavy duty, Vs. Light duty is pretty much Bullship....
And,...
If the Vintages are Different,...
Odds are the rotating assembley out of the Boat motor, won't fit into the other block, even With a ton of machine work...
Keeping the rotating assembley with it's original block will alleviate many of the mixin' & matchin' headaches that will undoubtingly pop up...

Even your link, just explains the differences in Vintages,+ differences from engine factory to factory...

 

[Rustychain]

Re: 4.3 rebuild ?'s

Ayuh,... BLah Blah Blah...

To Original Poster.
Read the link for yourself and make up your own mind.
Just trying to provide useful information that might help you out.

 

[Bronc Rider]

Re: 4.3 rebuild ?'s

I agree with bondo, only vintage is important.
A truck 4.3 is a common swap for a boat. The truck motors being the same as the boat engine, lasts just fine. The trucks cam profile can be used also. It shouldn't cause reversion.
I would change the core plugs, headgasket, transfer the marine accessories (i.e. starter, alternator etc,etc) and go boating.

 

[Silvertip]

Re: 4.3 rebuild ?'s

If the Blazer engine is earlier than '93 then there are two very different versions of that motor available. The "W" series was a balance shaft motor with the "spider" type of fuel injection system. The "Z" series was the base motor with throttle body setup. I don't remember off-hand if the "Z" motor had the balance shaft but if it didn't, the two blocks would not be the same.

 

[180shabah]

Re: 4.3 rebuild ?'s

There is nothing special about a MARINE 4.3 block. They do have brass core (not freeze) plugs and composite head gaskets, oh yeah they're also painted. That's it. Pull one apart and lookup the PN's for cam, crank rods bearings etc. It is all off the shelf GM stuff used in blazers, S-10 and so on. All those difference detailed in the link are why you NEVER mix two different 4.3's(short blocks anyway) there are just too many different combinations. Even during the same production year and code (w or z) different engine plants produced different "designs".

If the OP has a good blazer engine, he should use it. There are a few questions to be answered like the exact year of BOTH engines in question, but most of the other differences detailed in the link are just irrelevent.

 

[Bondo]

Re: 4.3 rebuild ?'s

Originally Posted by Bond-o
Ayuh,... BLah Blah Blah...

To Original Poster.
Read the link for yourself and make up your own mind.
Just trying to provide useful information that might help you out.

Ayuh,...

As am I,...
Without further muddying the already complicated situation with unnecessary irrevelant Info...

Like I said before,... DON'T swap the rotating assemblies between blocks...

 

[ssleeper94]

Re: 4.3 rebuild ?'s

i'm changing the cam to a marine spec'd cam and leaving the rotating assembly in the motor

 

[Bondo]

Re: 4.3 rebuild ?'s

i'm changing the cam to a marine spec'd cam.

Ayuh,... Whatever trips yer trigger,... It's Totally Unnecessary....