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LT-1 What Luck!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by K5krazy, Feb 25, 2001.

  1. K5krazy

    K5krazy Registered Member

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    I can't believe how lucky I am. I took the old tired motor out of my '72 and delivered it to the machine shop yesterday, and the guy identified it as and LT-1!

    Now we're trying to figure out how an LT-1 got into a '72 Blazer. The current theory is the factory must have run low on the standard 350 motors and to meet production needs they put in the LT-1.

    Does anybody think that is possible? Has anybody else run across a similar sitiation?
     
  2. BurbinOR

    BurbinOR 3/4 ton status

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    Since that truck is almost 30 years old, it could have been transplanted a while ago..........unless you are the original owner or know the original owner?

    That is a good find........

    <font color=orange>'79 - 406 TPI -<font color=orange> K5#5 - <font color=blue>See it at---&gt;<A target="_blank" HREF=http://www.blazzinor.coloradok5.com>http://www.blazzinor.coloradok5.com</A>
     
  3. jarheadk5

    jarheadk5 1/2 ton status

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    Aren't original LT-1 motors on the rare side? Even if it's tired, I would think it would be worth something. Unless, that is, I'm wrong...

    [​IMG] Semper Maintenance!
     
  4. Blazer1970

    Blazer1970 1/2 ton status

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    How does the guy know it's an LT1? Do you have the block ID number? The same casting was used to build the LT1 motors as was used for the truck motors.

    Tim

    70 Blazer CST 4X4 350 SM465 NP205
    87 Burb 4X4 350
    01 GMC 2500HD 4X4 Duramax/Allison
     
  5. Blue85

    Blue85 Troll Premium Member

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    That's right, the internals and the heads/manifolds are the difference. LT-1's weren't made in '72, either, so it must be a transplant (if it is really an LT-1).

    Didn't all LT-1's come fuel injected? Is your truck fuel injected or did someone convert it to a carb? Or is your friend just mistaken?

    <font color=blue>"Who are these guys?" --Al Gore, referring to busts of Jefferson, Washington and Franklin on a televised tour of Monticello.</font color=blue>
     
  6. Executioner

    Executioner 1/2 ton status

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    Opinions , opinions, I thought 72 was the prime year for LT-1
    What that Less Torque, or Light Torque ?
    Will the real LT-1 please speak up.
    How about referenceing some FACT"s
     
  7. jarheadk5

    jarheadk5 1/2 ton status

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    Executioner, what are you looking for, chapter and verse? There are so many inconsistencies in publications about GM products (this is FACT, I've read many conflicting things in books about GM products) that it's nearly impossible to truly VERIFY fact versus fiction.

    If someone asks for help, maybe YOU should bring out some of these FACTS that you seem to be so hung up on.

    [​IMG] Semper Maintenance!
     
  8. TX Mudder

    TX Mudder 1/2 ton status

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    Ok, I live in a cave.
    What's a LT-1?
    -- Mike
     
  9. K5krazy

    K5krazy Registered Member

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    o.k. Here is what I know - or think I know.

    The stamped number on the bock - (not the casting number) correctly maches for a truck of that year. I know this from Blazer books I have bought.

    The machinist told me that casting numbers on the block, heads, rods, main bearing journals, and intake manifold matched correctly for an LT-1. He got this information from some book he had full of casting numbers.

    I also know that the bearings are origional factory. I know this (once agian I think I know this) because the bearings were all different sizes. They vairied by increments of .0005 from journal to journal. I was told that only the factory did this. Something about it being cheaper for the factory to have different size bearings than to machine the thing constant.

    I also know (again!) that the harmonic balancer for the motor is bigger than normal. There is some other customer that wants to buy the thing from me.

    There is also something about factory hardening of the valve seats in the head which is going to save me some money because I don't need to have inserts installed. Which is fine by me!

    Another thing that is cool is the odometer is probally correct with 70k miles on it. The inside of this motor was clean, and there was very little ridge in the cylinders.

    So what do you think? Could I have an origional LT-1?
     
  10. Blaze

    Blaze 1/2 ton status

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    Alright, I don't know if this will help any, but I'm looking at a Car Craft right now that says that in 1970, the LT1 in the Corvette made 370hp, so that would mean that the LT1 was in production in 1972. If it was available in your truck, I don't know, but I know it was available in 1972.

    [​IMG]<A target="_blank" HREF=http://www4.ncsu.edu/~brschoch>http://www4.ncsu.edu/~brschoch</A>
    My truck beat up your SUV
     
  11. DMK

    DMK 1/2 ton status

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    An LT-1 should have aluminum finned valve covers, aluminum intake, holley carb, transistorized ignition. Will also have solid lifter cam. In 72 the LT-1 was only avaliable in the corvette.
     
  12. Blazer1970

    Blazer1970 1/2 ton status

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    There is some confusion above between the early '70s LT1, and the Gen 2 LT1 that was used in mid to late '90s F cars and Corvettes. We are talking about the '70s version. The block ID number is the last word on this. It is the number stamped on the block deck surface in front of the passenger side head. The last 3 letters are what is important. For an LT1, the letters would be: CGP, CGR, CGY, CGZ, CJK, CRS, CRT, CTB, CTR, CTU, or CTV. If the last three letters start with a T, it is a regular truck motor. What heads does it have? An LT1 should have 186s or 487s. If it has some of these parts, someone must have re-built it with some factory hi-po parts.

    Tim

    70 Blazer CST 4X4 350 SM465 NP205
    87 Burb 4X4 350
    01 GMC 2500HD 4X4 Duramax/Allison
     
  13. Executioner

    Executioner 1/2 ton status

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    When are those letters stampeed into the passeger side head ?
     
  14. Blazer1970

    Blazer1970 1/2 ton status

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    The letters are not stamped into the head, but into the block deck surface in front of the head. They are stamped at the engine assembly plant when the engine is assembled. I would assume (the following is not a FACT) that they are stamped at the beginning of the assembly line, as the machined block casting starts down the line.

    Tim

    70 Blazer CST 4X4 350 SM465 NP205
    87 Burb 4X4 350
    01 GMC 2500HD 4X4 Duramax/Allison
     

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