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Thread: 89 SC, need ideas for motor swap or rebuild?

  1. #1
    Join Date
    Mar 2006
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    Four Oaks, NC
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    57

    89 SC, need ideas for motor swap or rebuild?

    Ok Im toying with a couple of ideas for my 89 SC. I had it up for sale and decided not to sell it bacause I didn't want to take advantage of anyone. It was running fine when I first listed it for sale but as I kept driving it I realized something mechanical was going on with it. My temp needle started to fluctuate a lot depending on whether I was sitting still or moving and it was blowing steam out the exhaust even when it was 90 degrees outside. After having it checked out I was told it was showing signs of a head gasket problem, either blown or about to blow. The car still runs but misses really bad and overheats in a 3 mile commute to work. I have a lot of money invested in the car or I'd just junk it.I just had the clutch, tranny, tires, brakes, and battery replaced withing the last 6 months so its either cut my losses and sell the car cheap or fix the motor. I was told that with the mileage on the car that the block may or may not be rebuildable and I dont want to go as far as head gaskets without doing a complete build on it. So here;s what I feel like my options are, buy a lower mileage engine from someone here that runs and drop it in, buy a crate engine if I can find one, or possibly put a 5.0 HO in it. Im leaning toward the 5.0 due to cost reasons but what Im wondering is will I be able to use my existing crossmember and tranny. I know the radiator would have to be raplaced. Also, what kind of computer would I need to run the 5.0 with a 5-spd.Would I be biting off more than I could chew if I were to go this route. Otherwise Im gonna sell the car as a parts car for about $500 and be done with it. Any insight would be appreciated. Thanks.
    Last edited by repoman27; 06-19-2006 at 09:12 PM.

  2. #2
    Join Date
    Nov 2005
    Location
    Oregon 97220
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    1,017
    you could find a good used SC motor for $700 or so....
    5.0 won't go in there without an entire 5.0 harness, as i understand it....it'll bolt up ok though....I've actually been kicking around several ideas, one being selling my SC for 347 money for my LX. Although I am quite attached to the SC car.....Plus $2k won't get me anywhere near to running for a build like that..

    paul

  3. #3
    Join Date
    Nov 2002
    Location
    Palos heights, IL
    Posts
    2,538

    Thumbs up

    If its just head gaskets and possable raidiator, rebuild the top end. Lets say you have 150k on the motor. If it was maintained ie oil changes its still got a lot of life left. If you can do the work yourself I would say you will spend no more than $400. Get some Chevy ARP studs, felpro upper gasket set. have your heads resurfaced and valves reground by a machine shop and get a new raidiator and you should see 300k. Just dont drive it anymore and drain your oil now (if it has antifreeze in the pan) or you will loose your rod and main bearings, crank and related parts. If you have a shop do this expect to pay about $1200 to $1600. you can go ahead and rebuild the entire engine but don`t expect to get your money back out of it.
    Last edited by scbird1; 06-19-2006 at 10:38 PM.

  4. #4
    Join Date
    Aug 2005
    Location
    Central Arkansas
    Posts
    921
    I agree with above. A complete rebuild isnt really needed unless you have nasty noises, blue smoke, low oil pressure or something like 200K miles. I would do HG's and drive it until it gives you a good reason to rebuild it.

  5. #5
    Join Date
    Nov 2002
    Location
    Palos heights, IL
    Posts
    2,538
    Im on number nine mn12`s. Six of them needed head gaskets. Still looking for number ten.

  6. #6
    Join Date
    Mar 2006
    Location
    Four Oaks, NC
    Posts
    57
    I have had a lot of mn-12's myself. Most of them being v-8 cars. There is no telling how many miles are trully on the car. The cluster that was in it when I bought it read 167K but did not work. The title is labled exceeds mechanical limits, which I highly doubt, I drove the car about 8 months without a working speedo or odometer and then changed it out with one I bought off ebay. I put about 9K miles on it then came accross a great deal on a 145mph speedo and put that in there. I've put about 2K on it. My guess would be at least 200K and the car doesnt seem as though previous owners have taken great care of it mechanically. When I bought it and drove it home the oil change ligh on the vmm was blinking "now" and the oil looked like roofing tar. I'm really tired of putting money into this car but dont want to lose everything Ive got in it either. I know where I can get a 5.0 donor car for $500. Thats why I suggested that swap. A buddy of mine has a 91 LX that just had the motor rebuild last summer and he was t-boned about a month ago. Thanks for the ideas. I really doubt Im gonna put head gaskets on mine. If anyone has a good running descent mileage motor for a good price let me know.

  7. #7
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    Nov 2005
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    Oregon 97220
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    id sell ya my LX cheap, but you are a ways away......

  8. #8
    Join Date
    Aug 2005
    Location
    Central Arkansas
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    921
    If you just want a fun driver you can sell your engine, trans and SC goodies for enough to buy that 5.0 donor car and have a very reliable great looking and for once, great sounding SC. I had thoughts of doing that myself but mine runs too good, and I wont do it until the engine really bites the dust.

  9. #9
    Join Date
    Jun 2006
    Location
    Wilkes-Barre, Pa
    Posts
    263
    Quote Originally Posted by thirdbird
    you could find a good used SC motor for $700 or so....
    5.0 won't go in there without an entire 5.0 harness, as i understand it....it'll bolt up ok though....I've actually been kicking around several ideas, one being selling my SC for 347 money for my LX. Although I am quite attached to the SC car.....Plus $2k won't get me anywhere near to running for a build like that..

    paul

    Be careful with the 347. My 347 has an oil consumption problem and it seems the majority of 347 owners do as well.

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