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whats under my hood?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 79Cheyenne, Apr 10, 2000.

  1. 79Cheyenne

    79Cheyenne 1/2 ton status

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    I replaced all of the oil gaskets (valve covers oil pan timing chain and cover and rear main)and I noticed that my harmonic balancer was huge compared to all of the others I have seen and my fly wheel has weights on it does this mean I have a 400 SB or are there any 350's that are externally balanced? I cant get to the casting numbers without pulling the motor and since I finally stopped the leaks there is no way I am going to. How do I find out exactly what I have? where else can I look?

    79 blazer th350 350??400??

    <font color=orange>1979 BLAZER Cheyenne[​IMG]
     
  2. K5Junkie

    K5Junkie 1/2 ton status

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    I believe you can look at the freeze plugs on the side of the block. I think they were put in different places on the the 400 than on than on the 350's. I will double check that theory.
     
  3. '73 K5

    '73 K5 1/2 ton status

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    Right on. I had a 400 in a '79 Blazer once and I vaguely remember a mechanic telling me that he could tell it was a 400 by looking at the freeze plugs. It was either as you say they were in different places OR there were a different number of them. Good luck.

    '73 K5
    Chevy good...Ford bad
     
  4. Blazer1970

    Blazer1970 1/2 ton status

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    If it is a 400, the balancer will have a notch out of it (on the OD). Many truck 350s use an 8" balancer, same size as the 400, but they will not have the notch. Otherwise, post the block ID #, and I (or someone else) can tell you what you have.

    Tim

    1970 Blazer CST 4X4 350 SM465 NP205
    1987 Suburban 4X4 350
    1988 Chevy Pickup 4X4 350
     
  5. BillR

    BillR 1/2 ton status

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    Your VIN will have a code to tell you what came in the truck from the factory. My '79 has a 400, and the code is "R".
    Hope this helps!

    Blazin' in Flagstaff
     
  6. snidgen

    snidgen Registered Member

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    its simple the late model 400 has two freeze plugs the early model has three. as for the displacement you would need the number off the rear of the block. you should be able the read it with a good flashlight and the distributor out. if you email me the number i have a book with all v8 casting numbers
     
  7. 78Blazer

    78Blazer 1/2 ton status

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    You have a 400, same deal with mine the harmonic balancer was the first clue.. and the older 350s didnt need the weight on the flywheel they where internally balanced.

    Scott
    78blazer
     
  8. 78Blazer

    78Blazer 1/2 ton status

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    Just another hint about the casting numbers, I just took and cleaned the area where they were the best I could then I just took a piece of clay flattened it out and pressed it onto the numbers then pulled it off. and I had the numbers in the clay no need to pull the distributor.


    Scott
    78blazer
     

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