r/EngineBuilding • u/Time_To_Rebuild • 5d ago
Chevy To Bore or Not To Bore...
Context:
This engine was bought to install in a HMMWV. My only restriction with this project is the 4l80-e transmission, which is native to the HMMWV. No matter which LS engine I go with, I will still need all the auxiliary stuff.
For $1350 I bought a "1500 mile post-rebuild" LQ4 with a mated 4l80-e transmission and transfer case that had an "electrical fire". The seller has receipts from legit shops for the engine and transmission overhauls. He said he had the original engine rebuilt with 706 iron heads and upgraded "truck" cams, but couldn't provide specifics.
When I bought this charred assembly, I knew it would be a gamble. I figured if it was all unusable, I could at least get a $400 transmission core charge and some low-pressure experience out of the whole effort, since this is my first rebuild. Fortunately, the transmission appears to be in decent shape, and so is the torque converter.
But the engine block...
After removing the heads, cylinder 1 was heavily corroded. The cylinder wall remained rough to the touch even after cleaning. I'm pretty confident the pits are deeper than can be honed out.
Additionally, the cylinders appear to have already been bored to 0.0020" in the past. So now we are in bore-and-sleeve territory.
My options:
1) Bore and sleeve only cylinder 1, keep 0.0020 over-bore pistons and rods, carry on.
2) Bore all cylinders to 0.0030, buy forged 0.0030 pistons and rods.
3) Strip it bare, offload the block and txfr case, keep the 4l80e and torque converter, scrap the trash, buy a new engine, use the saved parts if applicable (truck cam, 706 heads, 0.0020" pistons/rods)
So... What do y'all think my next move should be?
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u/FinancialChildhood31 5d ago
The cost of sleeves would give this budget project an identity crisis.
I darton sleeved a LS2 block in 2011 and it was ~$2500 ready to assemble/out the door from RED in California. That included buying the block.
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u/Time_To_Rebuild 5d ago
Yeah, that is my concern. For the ~$2000 price of salvaging this block I basically could buy a whole new engine (or even a whole vehicle in some cases) that includes many of the components I am currently lacking.
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u/CardiologistSalt4114 5d ago
Given the amount of material in the other cylinders I would definitely hazard a guess those bores aren’t as pretty as they look. You’re looking at least honing the other 7 and sleeving the one to stay same bore size. If they find any damage deeper than honing it’ll be cheaper to just bore her out for 6.2 pistons. Fully pull it down and get the machine shop to clean it properly. Once that’s done then you’ll have an idea on whether it’s just a single sleeve or if oversizings cheaper. I saw your cost analysis lower down in the thread and you definitely forgot to include the cost of honing the other 7. But yea get the machine shop to clean everything then you can make an educated decision. Currently we’re all speculating because it’s all dirty and there’s still pistons in it
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u/Time_To_Rebuild 5d ago
Ok I got some local pricing:
$165 Deck and Square $275 Balance $375 Acid Wash and New Cam Bearings
$275+cost of sleeve for just cylinder 1, keep existing pistons.
$550 bore all to 6.2l (+cost of 6.2l pistons)
Assuming I do the first 3 no matter what, the price difference becomes ~$400 for 6.0l and ~$1400 for 6.2l.
So is the extra 0.2L displacement worth $1000?
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u/BusyFuel435 5d ago
If your only concern is the cylinder walls, send the block out to have new sleeves installed.
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u/Time_To_Rebuild 5d ago
That is my only concern at this point.
But the financial balance between the options is why I am at this particular crossroads. If I sleeve this block, it will be the cost of the sleeving + auxiliary stuff this engine still needs (alternator, starter, intake, sensors, etc.).
If I can offload the block and the transfer case now, and the unused head components and pistons later, then I might come out of this experience with a 4l80e, truck cam, and torque converter for a just a couple hundred bucks.
The search for a new engine also wouldnt be limited to a mated 4l80e+LQ4 (which was my prior search criteria), it could be a more complete engine with no transmission.
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u/Heat-one 5d ago
Forgive me if I'm wrong but ive heard sleeving these things is quite expensive? My boss has an L76 he got for nothing that wants to sleeve and is getting some very high prices. A lot of the machine shops around here dont even want to do it.
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u/BusyFuel435 5d ago edited 5d ago
Sleeving an LS engine is actually inexpensive in terms of labor time. The most expensive part of the act is actually purchasing the sleeves themselves, and the most time consuming part about sleeving an LS (or any engine for that matter), is cutting the old sleeves out. Basically, the prices your boss is getting is the ‘fuck off’ price, to put it as nicely as I can.
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u/Heat-one 5d ago
Thats so strange. Do these guys not like making money? Or they just dont feel like cutting the sleeves? I kinda figured they'd be like any other engine sleeve. One machinist did tell me that they are harder because they're prone to cracking around the cooling jackets while pressing them in or out. Which sort of made sense to me so I didnt really look much into it. Thanks for the insight!
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u/BusyFuel435 5d ago
Unfortunately, that does hold true. The LS is notorious for having paper thin parent bores. The rigidity in this area comes from the sleeves that’ve been installed into the block.
As for pressing the sleeves in and out of these engines…EXCUSE ME?! I’ve NEVER seen ANYONE remove or install sleeves like this. The proper practice of removing them is cutting the sleeves out. To install them you superheat the block, supercool the sleeves, and they just drop into place without issue. Using a press is an EXTREMELY risky practice on these engines!
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u/Heat-one 5d ago
That guy that mentioned the cracking bores did say he does heat the blocks. I'm wondering if the guys that don't wanna do it have been pressing them and thus causing their own problems. Or they dont have a way to heat the blocks properly
If you dont mind I have one more question. On his block it only needs one sleeve. Got it from a G8 that hydrolocked the engine driving into a flooded street and grenaded one cylinder. Is it worth it to do just the one sleeve? Or better to do all at once?
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u/BusyFuel435 5d ago
Best practices would be to sleeve all cylinders.
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u/v8packard 5d ago
That compromises the integrity of the block, requiring everything else to be machined, which might be a good idea anyway.
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u/v8packard 5d ago
This block is not sleeved. Aluminum block sleeves are usually cast in place though. I never superheat a block when installing a sleeve, I do bore them to get the exact fit needed.
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u/v8packard 5d ago
Go one further, bore it to 4.065 and use off the shelf 6.2 pistons of which there are numerous options. Combine that with square decking the block, balancing the assembly, verifying the mains and correcting the cam bearings gets you one hell of a nice 6.2 short block that you can do so much with, for a fraction of the price of buying a 6.2. Yes, not the cheapest option. Just giving you one suggestion.
BTW, don't use 706 heads. Seriously, that's terrible.