Rebuilding LT4 with 165k miles
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Teching In
Joined: Mar 2007
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Rebuilding LT4 with 165k miles So it's time to rebuild my 96 LT4, and I have never done anything like this. My automotive knowledge stops at oil changes and spark plugs. The car is making a bad internal noise, but it runs fine. It just makes a loud squeaking/chirping sound after it runs for a few minutes. Using a mechanic's stethoscope, it's definitely internal, not a belt or anything. My budget is $5,000. Also, I haven't been able to find a single quality performance shop in East TN. Lists of parts, things to do, etc. are greatly appreciated.
Sounds like a spun main, in which case it would probably be best to just throw the block away.
I sincerly hope I am wrong about that though.
The LT4 crank will be nothing but a LT1 crank once you turn it undersized to repair the damage. Undercut and rolled fillets will but ground into when they turn the crank.
The LT4 rods are fractured cap, going to have a hard time finding oversized OD bearings to allow you to rebuild them.
$5K wont go as far as you think it will. I would budget $4K easy for a nice shortblock since you likely have to replace about everyting anyway.
NICE parts that are a good value, you can do it cheaper but it will be cheaper in EVERY sense of the word. Avoid the cast aftermarket cranks they are weaker than stock. If you use cheap chinese components Scat is better than Eagle.
Understand power is in the topend not the bottom, if you do just a shortblock and give it a bit more cam but bolt the heads back on untouched it wont make that much power.
I sincerly hope I am wrong about that though.
The LT4 crank will be nothing but a LT1 crank once you turn it undersized to repair the damage. Undercut and rolled fillets will but ground into when they turn the crank.
The LT4 rods are fractured cap, going to have a hard time finding oversized OD bearings to allow you to rebuild them.
$5K wont go as far as you think it will. I would budget $4K easy for a nice shortblock since you likely have to replace about everyting anyway.
NICE parts that are a good value, you can do it cheaper but it will be cheaper in EVERY sense of the word. Avoid the cast aftermarket cranks they are weaker than stock. If you use cheap chinese components Scat is better than Eagle.
Understand power is in the topend not the bottom, if you do just a shortblock and give it a bit more cam but bolt the heads back on untouched it wont make that much power.
I'd sell the block for parts or scrap metal and look for a low mileage/rebuilt short block. Spend the remaining 4k or so on a nice heads/cam package, some bolt on's, and a tune.
Just for your learning sake, take the engine out and tear it down yourself. You'll learn an absolute crap load doing so. Keep the bearings numbered as to which journals they came from. That can help in diagnosing what went wrong.
I wouldn't be so quick to throw the block away. At least have it checked out to see if it is worth rebuilding. Agreed you can have a real nice short block for around 3 to 5K.
Are you looking for just out and out performance specific shops or are you looking into machine shops as well?
I wouldn't be so quick to throw the block away. At least have it checked out to see if it is worth rebuilding. Agreed you can have a real nice short block for around 3 to 5K.
Are you looking for just out and out performance specific shops or are you looking into machine shops as well?
I did not mean blindly throw the block away. I should have explained better that if a main spun, when the machine shop inspects it they are likely to tell you it would cost more to reapir than it is worth. Especially since it sounds like you have run it a bit trying to diagnose which would have done more damage.
I got a spun main block for free and looked into repairing it, found some .020 over OD bearings that might do the trick combined with a new set of caps BUT they are not a performance bearing. So even the guy who found the bearing PN and would have been making the money off the line bore suggested I find another block.
I got a spun main block for free and looked into repairing it, found some .020 over OD bearings that might do the trick combined with a new set of caps BUT they are not a performance bearing. So even the guy who found the bearing PN and would have been making the money off the line bore suggested I find another block.
Go to Powertrain Products and get yourself a brand new 4-bolt main original GM shortblock for $1k. www.powertrainproducts.net. Just get your heads checked, get them ported and have all new top-end components put in for about $3k, and put the motor together. Should put out some good power and run for a long time.
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Hey:
For a local shop, go here to the Regional Forums, Southern Members, and ask the TN guys there.
I hope that helps and good luck on your rebuild
Dub
When In Doubt Do Without
For a local shop, go here to the Regional Forums, Southern Members, and ask the TN guys there.
I hope that helps and good luck on your rebuild
Dub
When In Doubt Do Without
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Brett Foote
Teching In
Joined: Feb 2009
Posts: 23
Likes: 0
From: East Tenn
Where at in E Tn are you? I'm located in Anderson county by Norris lake. For machine shop you could use Top Gunn in South Clinton. I've also got a used shortblock from a 96 Trans am I'd let got for $200 but you may be better off getting a new one from the link above for $1k.
If you're close by you could swing by with it, or me by you, and I'd take a look at it or help turn a wrench or two. I've got a decent sized garage with a couple of tools.
If you're close by you could swing by with it, or me by you, and I'd take a look at it or help turn a wrench or two. I've got a decent sized garage with a couple of tools.
