Assembling a 4.3 MerCruiser v6 - Parts check needed

[Gibbles]

I know there is a block identification chart all over for these 4.3's
But what I don't know is if I can mix and match internals?

The new block vs the old one, I have a different crankshaft, balance shaft, and rods.

I'm tempted to grab the balance shaft from the old block and use it in the new block.
but then it's much heavier than the new one.
The new crank is also a heavier unit than the old crank!

So I'm guessing they should be a matched set?

I'm tempted to just swap the crank and balance shaft from the old engine to the new since it's absolutely mint condition and a mirror finish on the bearing surfaces!

But then the rods are a little different, so I'm wondering if they have a different weight.

and I'm trying to find my wife's old food scale to see if it can tell me how much different.

 

[Gibbles]

if these damn pistons weren't a press fit, I would just swap the pistons over to the old rotating assy.

 

[Scott06]

I know there is a block identification chart all over for these 4.3's
But what I don't know is if I can mix and match internals?

The new block vs the old one, I have a different crankshaft, balance shaft, and rods.

I'm tempted to grab the balance shaft from the old block and use it in the new block.
but then it's much heavier than the new one.
The new crank is also a heavier unit than the old crank!

So I'm guessing they should be a matched set?

I'm tempted to just swap the crank and balance shaft from the old engine to the new since it's absolutely mint condition and a mirror finish on the bearing surfaces!

But then the rods are a little different, so I'm wondering if they have a different weight.

and I'm trying to find my wife's old food scale to see if it can tell me how much different.

@Scott Danforth i think did a write up On 4.3 engine combos. WouldBe hesitant to mix and match. Best bet find a machine shop who can measure see what is there and catch any machining issues

 

[Scott Danforth]

Light reading. https://forums.iboats.com/threads/complete-history-of-the-4-3-liter-with-casting-numbers.693935/

 

[Scott Danforth]

If it was me, I would go to a you-pull-it, get a running 1998-2003 s-10 4.3 long block with under 100,000 miles

Swap the core plugs, swap the head gaskets, swap the circulation pump, then add the accessories and other items

Get a used vortec intake from ebay

You're then only out $500 vs the path you are currently on.

 

[Gibbles]

Thanks, I'll do some reading.

One reason for this block is that the new and the old block have the same casting numbers.
Old block being a 1994, the new one appears to be a 1995.

And i pulled one of the heads last night so i could do a visual and pull one of the pistons.

The rods from the new block almost look forged.

The old ones look cast, nearly the same shape other than the extra material at the ends looking damn close to being the same.

The old crank also has those 3 broken flywheel bolts that need extracting.

On the old block, the drain plugs appeared to be plugged as fk... lol

I hoped to see a clear cause of water intrusion into the oil, but so far that's a big fat negative.

And there is a nice set of machined non vortec heads available locally.
Asking 3, i bet i could score them for 200.

But then the whole "did the intake have water too?" Question.


More inspection today, wife brought home a nice cold from work.
Has me hacking up a lung today.

And so far the new block looks good, a quick inspection with some cylinder inspection tools suggests these are round and no taper.


The engine builder, i don't believe they ever pulled the balance shaft.
I pulled it, the front bearing had grease in the visible portion.
The back side was dirty as fk.

The bushing end had grit, lots of grit.
It needs a new bushing and the front bearing.
That front bearing is just another $50.

But the other balance shaft is nice and tight.


Yeah, i should have gone for the junkyard donor from the start.

 

[Gibbles]

Light reading. https://forums.iboats.com/threads/complete-history-of-the-4-3-liter-with-casting-numbers.693935/

Yeah, ****.
I can't identify the new engines crank, but I can identify the new rods and the old crank.

It looks like I have a romulus vs tokwanda (to lazy to spell check that).

The flywheel i have would be mismatched if I were to swap in what the new engine came with from the looks of it.

I'm thinking old rotating assy, and have the old rods switched to the new pistons.

 

[Gibbles]

Well I noticed I 100% have heavy pistons on the original engine, I see weights in there.

Now it makes me wonder about the whole flywheel mismatch thing.
none of the long blocks I see for sale have a flywheel that comes with them.

If I just run with the rotating assy on the new engine and the old flywheel, how much will it rattle that 22ft tin boat?

 

[Scott Danforth]

Tonawanda is the truck and boat and industrial engine plant

Romulus is the car plant

 

[Scott Danforth]

The flywheel i have would be mismatched if I were to swap in what the new engine came with from the looks of it.

Diameter?

Or crank mounting pattern?

 

[Gibbles]

Both blocks have the "t" on the sn.

The old crank is a T per the nice clear number.

The new rods have that 045 number on there suggesting the "R" plant/car thing...

So I'm assuming the crank is also a "R".
I can't identify the crank

The crank snout that sits above the flywheel mounting surface measures 2.066(ish)

Both have 6 bolts with a single locator pin for the flywheel.

 

[Gibbles]

Also, i didn't clarify.
It looks like both cranks are matching on the flywheel mounting end.
So i should be good there.

Also over the weekend i received my new main bearings for the .010 "new" crank, and i installed them.

Clearances came out pretty good.
And these new mains are waaay nicer than the king brand that it came with.

In the past i like to modify the thrust bearing for a little better oiling of the thrust surface.
And i was surprised to see that the bevel was already there from the factory!

I need to do some slight thrust clearancing to get the endplay a little looser.
It seems to be .0015 thou, i would like to be .0025 to .0030

 

[Gibbles]

Wife's cold she gave me had me floored late saturday and through sunday.
Definitely a nice fever to make things fun for me... lol


I guess i didn't mention that i drove out the oil galley plugs in this block on saturday.
More carb and brake clean.

Using some rifle cleaning brushes i got lots more crud out from this block.

Amazes me that the builder was so positive that their hot tank cleaning process didn't require any more follow up/cleaning.

I got lots of black crud out of the oil galleys.
And carb cleaner to remove the remaining paint on the block and crank.

And my distributor shaft is not .500, smaller than that, time to order more parts.

I'm leaning strongly on just running the rotating assy that the builder sent with the block.

If it vibrates, then ill plan on a junkyard block later.

And that brings me to the next question, is the flywheel on this thing the same as a manual s10/truck would have?

 

[Scott06]

And that brings me to the next question, is the flywheel on this thing the same as a manual s10/truck would have?

Yes it is just a manual flywheel

 

[Scott Danforth]

only critical thing on the flywheel is the diameter/ring gear. there are two diameter flywheels. a 14" with 168 teeth on the ring gear and a 12" with 153 teeth on the flywheel

 

[Gibbles]

Including the ring gear, I have a 14in flywheel.

 

[Gibbles]

Well i managed to get the short block assembled over the weekend, everything torqued and double checked.

Before rod/piston installation, the crank was spinning nice and free.
The new mains/thrust bearing has a nice bevel that clearances that un-worn surface perfectly.

I got the thrust clearance using some 600 grit, a piece of marble, and a little motor oil to a nice .003.

New balance shaft bearing and bushing installed.
I found a little heat on the front balance shaft bearing and a light wack with a hammer sent it free.

Then I stuck the balance shaft in the freezer before reinstalling.
Warmed the bearing up using a mapp torch, and it popped back on w/o much effort.

I removed all of the rings and cleaned them and the pistons in my ultrasonic cleaner, then wiped until no filth showed up on the rag.

Pistons with fresh bearings have been installed and rotating the assembly feels nice and consistent now.

 

[Gibbles]

Im thinking the heads will get cleaned, inspected, valves lapped, and new seals.

I would hate to spend money on a set of vortec heads if i end up getting a different engine anyways.

So I'm leaning towards inspect the best i can, and keep a close eye on the oil.

I'm going to install a catch can anyways, the current crank vent setup just made a mess of the engine.

The catch can will let me monitor how much water is vaporizing from the oil...

Head swap in the boat will be pretty easy, assuming I'm happy with the new engine that is.