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93 4.3 engine swap questions

Warren2019

New member
I have a 93 deck boat with a 4.3 that has a cracked block. I’ve been reading quite a bit and it sounds like a truck engine will bolt up. I came across a 94 S-10 with a 4.3.
I’m looking for any info on the compatibility and fit for these two engines. Im new to boats but am more than capable to pull an engine and swap it. I just want to make sure the years are a fit.
 
As long as the Marine components (ignition system, starter motor, alternator, fuel delivery system, etc) are used on the 4.3L S-10 engine, it can be made to work if the original engine was fitted with a Closed Cooling System, and if you bring the Closed Cooling System over to the S-10 engine.

However, if the original 4.3L engine was raw water cooled, and if you use the S-10 engine in a raw water cooled installation, you will eventually have an issue with the automotive head gaskets.



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As long as the Marine components (ignition system, starter motor, alternator, fuel delivery system, etc) are used on the 4.3L S-10 engine, it can be made to work if the original engine was fitted with a Closed Cooling System, and if you bring the Closed Cooling System over to the S-10 engine.

However, if the original 4.3L engine was raw water cooled, and if you use the S-10 engine in a raw water cooled installation, you will eventually have an issue with the automotive head gaskets.



So if I just change out the head gaskets then am I good? I figured I’d have to change the add on items already. But didn’t consider the cooling system difference. Also another response was mentioning the cam. How much is that needed? I’m good doing what is needed but want to make sure it’s all done before the new engine is sitting inside the boat.
 
As long as the Marine components (ignition system, starter motor, alternator, fuel delivery system, etc) are used on the 4.3L S-10 engine, it can be made to work if the original engine was fitted with a Closed Cooling System, and if you bring the Closed Cooling System over to the S-10 engine.

However, if the original 4.3L engine was raw water cooled, and if you use the S-10 engine in a raw water cooled installation, you will eventually have an issue with the automotive head gaskets.



So if I just change out the head gaskets then am I good? I figured I’d have to change the add on items already. But didn’t consider the cooling system difference. Also another response was mentioning the cam. How much is that needed? I’m good doing what is needed but want to make sure it’s all done before the new engine is sitting inside the boat.



Yes change head gaskets for marine and core plugs to brass or stainless is all that is typically done to convert a truck engine. If it is a car engine swap the cam as well.
 
But use only the block. Swap everything else from the marine engine over to the "new" engine including the intake manifold.
 
Hi I did this last winter check the block number of the boat engine and find the truck block that has the same number its not hard to find them otherwise you will run into metric bolts in different places good luck if i can help get back to me mike
 
Hi I did this last winter check the block number of the boat engine and find the truck block that has the same number its not hard to find them otherwise you will run into metric bolts in different places good luck if i can help get back to me mike

strictly bolts on a later vintage 090M casting are on the side motor mounts, flywheel cover (both M10) , and starter motor. $20 at hardware store plusa set of correct stater bolts ($20 or so ) will fix the issue
 
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So if I just change out the head gaskets then am I good?
Warren, you could run the auto head gaskets for a while.... but they will eventually begin to fail due to the unfavorable PH balance of river/lake water.... or worse yet.... ocean water!

I figured I’d have to change the add on items already. But didn’t consider the cooling system difference. Also another response was mentioning the cam. How much is that needed? I’m good doing what is needed but want to make sure it’s all done before the new engine is sitting inside the boat.
The auto camshaft may not be suitable in that the over-lap (if excessive) may cause exhaust gas reversion.
Reversion can cause the cylinders to pull exhaust water back into the cylinders at low engine RPM.

If the camshaft is the roller type, you can bring it and the cam followers over to the replacement engine.
If it's a flat tappet cam, you would want to keep each cam follower on the same cam lobe as they were previously..... but even at that, it is not recommended.

When adjusting the hydraulic cam follower plunger depth (what some call adjusting valves), be sure to use the 6 stop static procedure ...... not the 2 or 3 stop.
Start with #1 cylinder at TDC C/S.
Adjust the plunger depth for both intake and exhaust.
Roll crank around 120 degrees, and adjust for #6.
Repeat right on down the firing order.




Dang I was expecting another pages-long debate over quench-effect pistons from the Master.

I am sorry that this disappoints you.
Warren is not building a 4.3L, he is retro fitting an auto version for Marine use.


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Hi There is no need to go to the hardware store for anything (i would not use hardware store bolts on any engine) as long as you know where they are and are different you remove and use the ones from the metric block then you have no problems with quality or fit. mike
 
Hi There is no need to go to the hardware store for anything (i would not use hardware store bolts on any engine) as long as you know where they are and are different you remove and use the ones from the metric block then you have no problems with quality or fit. mike

I guess your hardware store doesn’t carry grade 8 us size or 8.8 or 10.8 metrics?

if you look at the OEM fasteners very few are even grade 8
 
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You answered your self oem fasteners are what you need. not what you want to guess at putting in its place

Buy what ever bolts makes you happy.

Bottom line OP shouldn't be dissuaded from getting a metric block if he finds one, as with absolutely no guesswork one can get what fasteners they need to swap marine flywheel cover etc
 
I get all my hardware from McMaster-carr. If you haven't used their shopping portal, it is a rabbit hole. That is not to say it's confusing...quite the opposite; one of if not the absolute best webtail UI and experience out there. Unfortunately you must buy in bulk lots, like 25, 50, 100 etc. This is actually not as bad as you think since most fasteners over say 3/8 come in 5 or 10 so if you're purchasing something like bolts for the flywheel you might have two left over. Even so, it's usually less expensive than buying individual fasteners in Quicksilver bags. They don't sell junky junk from India or whatever. Every fastener has a click thru to it's spec sheet where you can get engineering data even download 3D models...but don't stop at just the fasteners...they have everything. Think Grainger on steroids.
 
I get all my hardware from McMaster-carr. If you haven't used their shopping portal, it is a rabbit hole. That is not to say it's confusing...quite the opposite; one of if not the absolute best webtail UI and experience out there. Unfortunately you must buy in bulk lots, like 25, 50, 100 etc. This is actually not as bad as you think since most fasteners over say 3/8 come in 5 or 10 so if you're purchasing something like bolts for the flywheel you might have two left over. Even so, it's usually less expensive than buying individual fasteners in Quicksilver bags. They don't sell junky junk from India or whatever. Every fastener has a click thru to it's spec sheet where you can get engineering data even download 3D models...but don't stop at just the fasteners...they have everything. Think Grainger on steroids.


X 2 on McMaster my go to spot at work for many items and obscenely quick shipping. I'm lucky enough to have an old school hardware store two aisles of fasteners, only thing they didn't have was grade 8 studs for two spots on the flywheel cover.
 
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