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5.7 rebuild.....

C

Cariboo

New member
Hi all. Thought i would post on here to get a bit of advice...
I bought a 24' bayliner this past summer, Happy with the purchase... even though the motor needs a bit of tlc...
The boat is a 2000 year and came with a 5.0 and previous owner put in in 2015 a New mercruiser 5.7, roller block with 902 vortec heads. Edelbrock marine intake and 1409 carb, dynoed at 305 hp when installed. Paired with a B3 drive.... Nice combination.... 370 hours since 2015
When put in lake it seemed to run smooth, start easy.. but no power. I ended up replacing the cap, rotor and plugs as they were original from 2015.. I set base timing to 10 btc.. tried again, better but not quite up to rpm at wot so i gave it another couple deg and got it to 4700 ... At that time i was happy but thought it should have a bit more poop....
Now in shop for winter... I pulled drive and motor and I now know that besides oil changes this thing hasnt seen much maint since 2015.. Plus i want to clean and paint bilge, re wire as the wiring is a mess and replace all hoses to black and fresh water tanks...

OK.. Did comp check on motor.... hole 4&6 were at 90 & 140 and hole 5 at 150. the rest were between 160 & 170....
Did leak down and seemed to be leaking via valves... Hard to tell, but hole 4 wouldnt hold any air

Time to tear down... One thing i am very happy with is the cleanliness of the internals... so it looks like oil has been changed and no over heating...
Pulled heads and they look good, a bit of carbon build up, no visible cracking.... I am taking them to local speed shop to get re done.

I was hoping not to touch the bottom end.......
Mic'ed the cyl's and they are not too bad, within 1-2 thou on most, No scoring, No ridges.. But there is a bit of corrosion wear on 4 & 6 and on 5 and minor corrosion on a couple more.... I would say from leaking risers and sitting all winter.. Not enough to sieze motor, but enough to bugger ring seal....

So , I dont think a good hone will work... even with new pistons I think there will be too much clearance..... so Im looking at going 30 over, and new pistons....

Now the ???'s... Its been decades since i rebuilt motors and WOW there are a lot of choices for pistons these days...... I dont want to cheap out....
I have to watch out for my CR as with the vortec heads its real easy to get high comp... I want to stay below 9.5 ish so a dish piston with -12cc..... That will give me a bit of lee way incase the heads and block deck need to be shaved 0.010......

The piston i kinda like is the Keith Black kb 193.030....
others are....dss sx series 8103-4030, wiseco pro tru street pts508a3, sealed power h423dcp
Can anyone give me there opinion or suggestion please.

I am not looking for a hi performance motor, just a solid, reliable runner... will be using boat in ocean, west coast of BC... need reliability....
TIA

Cheers
 
Not certain what the complete engine looks like - my guess is the 5.0 bolt-ons went onto the new 5.7 block...so what is the fuel delivery system - carb or EFI...and .which ignition system is on it? Lots of combination available in the late 90's thru early 2000's...
 
makomark said:
Not certain what the complete engine looks like - my guess is the 5.0 bolt-ons went onto the new 5.7 block...so what is the fuel delivery system - carb or EFI...and .which ignition system is on it? Lots of combination available in the late 90's thru early 2000's...
Click to expand...
Read my post. All info is in it
 
Seeing as its a 24 ft and a Bravo,
I would suggest a remanufactured 383 and all accessories will bolt up.
Keep the build specs around 350 hp.
Then add a good intake ans carb.
Unless your parts and machine costs are going to be under $3000-4000. I would go to a 383
 
kghost said:
Seeing as its a 24 ft and a Bravo,
I would suggest a remanufactured 383 and all accessories will bolt up.
Keep the build specs around 350 hp.
Then add a good intake ans carb.
Unless your parts and machine costs are going to be under $3000-4000. I would go to a 383
Click to expand...
Ya a ballanced stroker assembly would be nice, wasnt planning on diving this deep into the more as it is....
My budget will allow to bore the block and get a good set of pistons...
Looking for advice on piston brand for marine use....
 
How about flat tops and thicker head gaskets? .010" combined is a lot of material. Better to stay around .005" ish if possible...if you go to much it may interfer with the intake alignment...
I am no piston expert at all but the 4 you mentioned will all work.

This is not a highperformance engine.
It is a marinized truck block.
Most truck blocks use cast pistons. Only severe duty may see forged.
Its all about the $$$$

Cyl bore, crank polish and new bearings, heads/block plained, fresh pistons and rings.
Should get many years out of it.

just my thoughts...
 
kghost said:
How about flat tops and thicker head gaskets? .010" combined is a lot of material. Better to stay around .005" ish if possible...if you go to much it may interfer with the intake alignment...
I am no piston expert at all but the 4 you mentioned will all work.

This is not a highperformance engine.
It is a marinized truck block.
Most truck blocks use cast pistons. Only severe duty may see forged.
Its all about the $$$$

Cyl bore, crank polish and new bearings, heads/block plained, fresh pistons and rings.
Should get many years out of it.

just my thoughts...
Click to expand...
ya.. flat tops with -6cc will give me 9.7:1 thats if no planing is done and i go with a 0.039 head gasket... a 0.030 head gasket was in there...
Thats the top end for CR... dont want to have to run 91 oct gas ,, 89 oct is the std marine fuel in my area...
Pulled the pistons today and they all look really good... Too bad there is some corrosion in a couple cyl's otherwise ide just hone and re ring... Rod journals on crank are spottless, all miced out the same at 2.0995.... Im expecting the mains to be the same, so just a light polish and new brgs.
I do want to go forged pistons though, boat will be running full load at 3800-4k for extended periods....
Im also going to upgrade risers to the dry joint ones, try to keep water away from the exhaust ports... Fukin wet exhaust....lol
 
You can throw a pile of money into a "high performance" engine but at the end of the day, you are pushing the same hull with the same drive. You aren't going to get more than a couple knots extra at WOT. Hardly noticeable and not worth the extra thousands. Of course, nobody wants to hear that ha ha. Just build it reliable and keep the CR where you can use normal fuel. 5.0 is not exactly a performer anyway even with extra work.
Thankfully the former forum member who shall remain nameless would have filled three pages by now with his ideas about the "right" way to do a build so you are spared!
I think Ghost's idea of a remanned 383 is the way to go. You'll get up on plane faster and even tho you won't go a whole lot faster at the top you should be able to squeeze another 10 knots out of the rig with it.
 
o2batsea said:
You can throw a pile of money into a "high performance" engine but at the end of the day, you are pushing the same hull with the same drive. You aren't going to get more than a couple knots extra at WOT. Hardly noticeable and not worth the extra thousands. Of course, nobody wants to hear that ha ha. Just build it reliable and keep the CR where you can use normal fuel. 5.0 is not exactly a performer anyway even with extra work.
Thankfully the former forum member who shall remain nameless would have filled three pages by now with his ideas about the "right" way to do a build so you are spared!
I think Ghost's idea of a remanned 383 is the way to go. You'll get up on plane faster and even tho you won't go a whole lot faster at the top you should be able to squeeze another 10 knots out of the rig with it.
Click to expand...
yes thankfully said forum member is history.

to op

these engines were 9.4 from factory. Get stock replacement pistons and be done with it. not having forged pistons is not why this engine failed…
Your machinist should be able to set you up with that and price out a stroker crank. Boat that size would think you would benefit from the displacement.

you can also look for long blocks from michigan motorz or other marine engine suppliers compare vs machine work on yours
 
Dieter said:
yes thankfully said forum member is history.

to op

these engines were 9.4 from factory. Get stock replacement pistons and be done with it. not having forged pistons is not why this engine failed…
Your machinist should be able to set you up with that and price out a stroker crank. Boat that size would think you would benefit from the displacement.

you can also look for long blocks from michigan motorz or other marine engine suppliers compare vs machine work on yours
Click to expand...
No where near 9.4.... Even with vortec heads...
My motor speced out at 8.75, with the stock 16cc pistons....
Decks were way out of square so pistons ranged 0.029 - 0.036 down the hole.0.030 gasket.. Thats 0.060 quench and not even......
Turned out that there was some leaking by the head gasket between 4&6.... Head was dished 0.0035...
block and heads have now been hot tanked and inspected.. No cracks. Heads are going to get a 0.005 clean up. Due to some corrosion wear in a couple cyl's the block is getting bored 0.020.
New pistons are KB hyper 12 cc inverted dome. D shaped dish will match the vortecs quite nice.
Block deck will be squared up and shooting for pistons to be sitting down 0.015
Once pistons are fitted in bores and measured, valve clearance checked, I will then pick the correct gasket thickness. Looking for no more then 0.045 quench...

Calculated CR will be 9.5... will be a bit less due to blowby and head gasket volume not calculated in... Should be good for 89 oct fuel as that is what we have for marine fuel....
I will be re using the oem roller cam and lifters....
As well as re using the Edelbrock Marine performer intake and the 1409 carb which will get a clean up....When the motor was installed in 2015, it was dynoed at 305 hp... Even with that shotty production GM/Mercruiser build..... not going to dyno it, but am confident it will be north of 300 hp which is fine for what im using it for... Its a fishing boat.....
FYI parts and machining will be around 4K, Canadian $$'s.... The freakin new manifolds and risers are the kicker.. Going wit dry joint,, $2500 can $'s.....
 
I am 100% but something doesnt appear right.

I wonder if that was a remanufactured block?

I thought the factory head gaskets were around .046" not .030".

I used a multi layer .030" on my Harley with 6cc domed forged pistons for a quench of about .033" and running 10:25 to 1 compression.
I have had the heads off and it looked just like it should. Nice contained combustion area.

I wonder what the Felpro marine gaskets are for stock replacement?
 
kghost said:
I am 100% but something doesnt appear right.

I wonder if that was a remanufactured block?

I thought the factory head gaskets were around .046" not .030".

I used a multi layer .030" on my Harley with 6cc domed forged pistons for a quench of about .033" and running 10:25 to 1 compression.
I have had the heads off and it looked just like it should. Nice contained combustion area.

I wonder what the Felpro marine gaskets are for stock replacement?
Click to expand...
The block was new, cast in 2014 in mexico, along with the 902 heads and crank...
Im not sure what year but gm moulds made there way to mexico, but they did so they could keep casting older style blocks and heads for various markets,,, Marine apps...
They have a few mods from original castings like longer cyl sleaves on blocks and more meat in the heads where they were prone to cracking...
The castings themselves are good, the production machining.... well its production machining...
Most sbc are out of square, BBC are even worse... Its just nice that there is enough metal to correct it, even using std. CH pistons...
 
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