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Got a free LT1... It's spun out

Discussion in 'Engine Topic' started by Da_Raabi, Oct 19, 2020.

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  1. Oct 19, 2020 #1
    Da_Raabi

    Da_Raabi Veteran Member

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    Last week I was given a free LT1 aluminum head 5.7 out of a 95 Trans-Am. I knew nothing about the motor other than the "fact" that it "ran when pulled". I got it up on a stand and started tearing into it and found... well I found issues.

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    I really got my hopes up when I took a look at the top end. This thing was CLEAN. Not a spot of gunk or grime. Intake runners in the heads looks like they had barely even been run. Much of everything else top end was the same. Barely run.

    20201013_165233[1].jpg
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    It was all fun and games until I pulled the oil pan. That's when the 'ol heart dropped right into my shoes.

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    Yikes! Babbit material for SURE.

    Long story short, I've got 3 spun rod bearings. One so bad it had actually worked one bearing shell into the other. NOT GOOD.

    The crank looks like maybe it could clean up, but obviously the rods will need to be looked at too.

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    So here is the thing. Do I look into grinding down this crank and the rods and run what I have, or should I look at a new crank? I see Eagle cast 5.7 cranks are less than $200. But I'd still need Rod work done, not to mention balancing. The other option is to throw caution to the wind and pick up a kit like this:

    https://motorsportsunlimited.com/lt...draulic-roller-camshaft-choose-options-below/

    The nice thing about this is that it provides pretty much everything I would need to get the engine running again (besides a carb swab intake and associated bolt-ons) and is within a couple hundred bucks of what I estimate it would take to bolt this thing back together with the OE crank/rods. Plus it's a 383 set up which would be SICK. My price comparison is assuming new timing set, cam, bearings, rings, etc would be needed. I don't know what crank/rod machining costs, but if it's any more than $2-300 the final price would be right in the ballpark of this all-inclusive kit.

    So I guess I'm just throwing this out there to get ideas. I've never built an engine from the bottom up before so I want to make sure I do it right. Plus I don't really want to have to do it again. Since I'm into this for $0 so far, I figure building up the bottom end a bit would be worth while.

    I'm just really glad this thing was free!
     
  2. Oct 19, 2020 #2
    biker

    biker Veteran Member

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    Make sure your block is ok too. Sometimes a spun bearing will require main saddle machining to make it serviceable again.
    If the block needs work, and you are going to buy a complete rotating assembly anyways, you may be better off finding a good block. And really, are you going to run it as a true LT1 with the reverse flow cooling, questionable opti-spark system and restrictive intake? The only value to that engine is if the block is ok.
    The up side to an LT1 and most injected engines is that they DO run super clean and the bores hardly wear at all.
    I thought only the Corvette got the aluminum heads? Trans Ams and Camaros got the iron heads. I could be wrong though.
     
  3. Oct 19, 2020 #3
    Da_Raabi

    Da_Raabi Veteran Member

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    The plan is to swap out the intake with a GM carb/HEI intake and completely ditch the optispark.

    The heads need to be cleaned a little, but they look to be in fantastic shape - and yes the partial VIN comes back to a '95 Pontiac - i.e. the Trans-Am.

    These LT1's are neat motors. I like that they are a hybrid blend of new and old tech. I'll definitely be having the block checked over, but fortunately I did not find any spun main bearings or obvious signs of wear and tear on the block. Hell, the cylinders still have crosshatch on them! If it had not been for the spun rod bearings, this thing would have been ready to run!
     
  4. Oct 19, 2020 #4
    1980RS

    1980RS Veteran Member

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    The newer LT1's can make power but with the reverse cooling and FI it's kind of a pain to transplant when an LS swap is much easier. I don't know how many people spin bearings on those engines as the clearances are way too tight from the factory and with people spinning them to 5500 rpm won't be long before there is trouble. Knew a guy who had a factory '97 SS LT1 and went through 2 engines in one summer with spun bearings.
     
  5. Oct 19, 2020 #5
    badazz81z28

    badazz81z28 Veteran Member

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    If the intent is to stay on the cheap because it was free, just replace what needs to be replaced. If you're looking to invest money into a new crank....stroker is the best path forward. I personally wouldnt invest in it as you can get a LS for the cost of going wild on the LT.
     
  6. Oct 19, 2020 #6
    sandlapper

    sandlapper Veteran Member

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    spun main Gen II LT1 Too much trouble; part it $ out & get/build something else.
    Don't see a single Gen II-based crate in Chev/GM perf catalog; that tells me enough.
    an L31 Vortec 350 truck motor from 96-2002 (w/ vin code R) makes a great platform w/ big potential & is easy to retrofit carb & HEI; brackets & accessories direct swap.
     
  7. Oct 19, 2020 #7
    mallard

    mallard Veteran Member

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    Not trying to rain on anyone’s parade but free or not (now you know why I guess) and factoring in your labour, rather than pi*sing around with this for hours on end and spending who knows how much $ are you better off investing in a known good engine?
     
  8. Oct 19, 2020 #8
    biker

    biker Veteran Member

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    Exactly. If this is your first venture into hotrodding an engine, dont go broke doing it. Dont despair though, you have some good parts there. Be like the rest of us... start a collection of good parts, trade or sell to get stuff you want. That is a good block, if the mains aren't damaged, the heads look nice, optispark and water pump are worth a few bucks to an LT1 die hard that needs them.
    As Sandlapper mentioned, find a good vortec 350 motor out of truck or a tahoe. A good intake, manifold and cam along with the right valve springs and retainers/locks and you have darn near 400 hp.
     
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  9. Oct 19, 2020 #9
    Lowend

    Lowend Administrator. .a car, a man, a maraca. Staff Member Lifetime Gold Member

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    The LT1 engines certainly aren't bad MSD seems to have solved the Optispark issues (finally).
    With aftermarket crankshafts being so cheap these days, I rarely see a reason to refurb a factory unit.

    I guess the question is: How dedicated are you to this engine?
    I would bet you could redo the LT1 for about the same amount of money as doing aftermarket EFI on a conventional smallblock.

    Back in the Speed Merchant days, we did a couple of absolutely savage 396 (3.875" crank) LT1's
     
  10. Oct 20, 2020 #10
    351maverick

    351maverick full time Ebay seller/hustler/car killer

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    Da_Raabi IGNORE the guys that say your LT1 is a waste of time

    aluminum heads, powdered metal connecting rods (most, not all), roller cams and the ability to bolt in place of a gen1 SBC are FANTASTIC reasons to build one of these

    a LS swap will be SO much more work and a ton more $$$ (yeah guys will say they LS swapped their car for $200 total investment are full of it)

    I part out many many 4th gen LT1s and I see spun bearings ALL the time

    285 horsepower STOCK...they are awesome motors that most are scared of because of the weird cooling & optispark but you're a smart guy - eliminate that with the conventional intake & you're all set

    if you can't tell I LOVE an aluminum headed 4th gen 94-97 LT1
     
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