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Gettin ready to swap in my 402 Big Block.....Questions..

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Zeus33rd, Sep 22, 2002.

  1. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    Been building a 402BB for my K5, and I'm gettin down to swap time. Got a few questions...First, will the BB oil pressure and water temp sending units work with my gages? Second....This might seem like a "newb" question, but what weight and type oil should I use in this thing? Conventional, semi sythetic, or full synthetic? Third..Big block and small block motor mounts are the same right? Fourth...lol, How long do ya'all think my TH350 is gonna live behind the big block before it barfs it guts out? /forums/images/icons/grin.gif /forums/images/icons/grin.gif
     
  2. Swanson52

    Swanson52 1/2 ton status

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    The guages will work with the BB sending units, the motor mounts are the same, but not 100% sure on the break in question. I have heard arguments both ways on this; use conventional to break it in, then switch...or go ahead and run synthetic from the get go (I even know people that still swear by using non-detergent oil for break in). I have used conventional then switched with a new motor, and no problems that way.
     
  3. Sandman

    Sandman 3/4 ton status Author

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    I had to get an adapter for the oil sending unit. I tried the correct sending unit but it hit the headers. I ended up putting in an elbow to make it all work. The threads are different sizes.
     
  4. Z3PR

    Z3PR Banned

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    Pic's man, pis'c. Nothing in the world like a big block !!! I'm enveious.
     
  5. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    Swanson and Sandman, Thanks a bunch for the input. Much approciated. /forums/images/icons/grin.gif /forums/images/icons/grin.gif

    Z3PR- I'll grab some pics of the motor itself on the engine stand today. No intake on it, but It still looks pretty bad ass. /forums/images/icons/cool.gif /forums/images/icons/laugh.gif /forums/images/icons/grin.gif
     
  6. 4x4Freak

    4x4Freak 1/2 ton status

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    I wouldnt waste the money to start out on sythetic oil because you will need to change it right after initial breakin.

    I'm fixing to switch to synthetic when I can afford it.
     
  7. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Stay away from synthetic oil, it is for the cheap bastard that doesn't want to change his oil. There is no reason not to run plain old regular oil. Assuming that you keep your oil and filter changed every 3,000 miles or whenever it becomes dirty from too much fuel dilution. IMHO synthetic oil is overrated. Just my thoughts, I know there will be a lot of people who disagree with me but thats ok everyone has their own opinions.
     
  8. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    Cool..Thanks for all the answers and stuff. Kinda what I figured ya'all would say about the oil thing. Scott/4x4High told me the same thing a couple weeks ago when he was here... So I guess the next question is what weight oil should I run? 10/30, 10/40, 20/50? I'm pretty sure I'll go with Castroil or Valvolene. Heard a few negitive things about Pennzoil...Anyways...thanks for all the help guys. /forums/images/icons/laugh.gif
     
  9. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    You need to determine the climate you live in what is best for you. I would say 10/40 is fine. The worst thing you can do is to keep changing viscosity's of oil from one to another. Once you have determined what you want stay with it.
     
  10. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    How does the climate determine what vicosity to run? Does it have to do with temps and weather? Why 10/40 as opposed to 20/50 or 5/30 or 15/40? Apologize for all the questions....I just figure that knowledge is power. /forums/images/icons/smile.gif
     
  11. POWERMAD

    POWERMAD 1/2 ton status

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    I use Delo 15/40 oil in all my rigs.
    But to break in the cam and then go seat the rings I would use Valveoline 10/40.
    Be sure to prime the block and make sure that the valves are set the first time.
    Especialy with a BigBlock engine.
     
  12. Zeus33rd

    Zeus33rd Smarter than you GMOTM Winner

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    Hmm....Maybe I should clarify a bit....The motor hasn't been totally rebuilt, as in new cam, rings ect...I bought the truck it was in for $300....It had a blown head gasket. The heads were resurfaced and given a valve job. All the bearings were inspected for damage ect ect. Scott/4x4High works in a machine shop and did all the head work for me....Also adjusted the valves ect and inspected everything. So this motor is not totaly new rebuilt. I'll still do the break in thing as if it was new stuff though. /forums/images/icons/grin.gif
     
  13. POWERMAD

    POWERMAD 1/2 ton status

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    That's cool.
    Drop er in and go.
    As to the tranny.. a decently built 350 will stand up to your plant.
    One of the dayshift guys has a 72 with a 402 he built, that thing will smoke the tires on it. it has a TH350/205
    38x11" boggers, he did a 17 sec 1/4 mile in the truck drags with it.
    14 bolt and D60 too, 4:56 gears.
     
  14. Z3PR

    Z3PR Banned

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    I used to run Valvolene 20/50 in my 454, and 383 strokers. Only draw back is it's alittle harder to crank over when it's cold out. I'm runninng 10/40 in my stock 400 small Block. 84,000 miles on it, it's had 10/40 it's whole life, so that's why it still gets it. If I find a big block, rebuild it to my standards, then I'll go 20/50 again.
     

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