350 teardown oddities.

Discussion in 'Small Block Tech' started by UNDERDOG350, Sep 27, 2019.

  1. UNDERDOG350

    UNDERDOG350 350 Buick purestock racer

    Not sure what year they started casting 5.7 onto the 350 block. It's on the side by the casting number 25504744 and also above the bellhousing. Also never seen the 4-LINE cast in the bell housing area. Check out the casting flash on the crankshaft. Main cap on the left and rod bolt to the right. This photo was after I broke several pieces off with just my fingers.
    The heat shield over the LH exhaust manifold has an extension welded to the bottom and looks like it had a heat riser valve. It is flat. Not sure what year this is. Has cap screw rods I will be posting for sale in parts.

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    Last edited: Sep 27, 2019
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  2. Mark Demko

    Mark Demko Well-Known Member

    '77 and up block I'd say since it has 5.7 cast into it.
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  3. Mark Demko

    Mark Demko Well-Known Member

    My opinion is the tooling was breaking down on the later blocks, they weren't as "precision" as the earlier (up to maybe '73 350 blocks)
    Reason I think this is the '78 block I had in my GS, the main caps fit loosely in the register/s of the block, whereas my original '71 block that's back in my GS fit with a light tap from a mallet.
    The cam bearing bores on the '78 had a knurled pattern in 'em, like they were too big to begin with.
    No provision for a windage tray on the '78 block.
    No block drains.
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  4. Aaron65

    Aaron65 Well-Known Member

    Is this the engine in your '73?
  5. telriv

    telriv Well-Known Member

    When I redid the engine in my Dads '72 Skylark I found some oddities. Now my dad bought this car new in '72 & other than replacing a leaking intake manifold gasket, has NEVER been apart.
    Jump ahead 27 yrs. & my mom gives my youngest the car as he was interested in restoring it. Pulled the engine & trans. for a rebuild.
    1st. thing I found was that were were NO ex-panders behind 3 oil rings. Could be a reason why it used a quart of oil every 1K-1.5K miles or less IF I was driving it. Upon assembling the short block put rod & piston assembly in No. 1 cylinder, torqued down & I couldn't turn the engine over. IT WAS DEFINITELY LOCKED UP. After doing this a few times I continued on with the other 7 & there was no further problems. Went back to no. one & it was locked up. After looking at it MANY times I just couldn't figure it out. Brought the piston & rod assembly to the machinist I use for him to take a look at. Took the cap off then popped out the rod bolts. While he was doing that the phone rang. ALL the time while talking he was looking at the rod from ALL diff. directions & angles. Then his eyes lit up. When he put the phone down he asked me to look at the holes in the rod. I couldn't see anything. He pointed it out to me. The holes in the rod were BOTH partially drilled crooked. The factory probably backed up & re-drilled. This is ALL from the factory.
    How the hell did the factory start it????
    20 yrs. later it's still running fine.

    Tom T.
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  6. UNDERDOG350

    UNDERDOG350 350 Buick purestock racer

    Thats wild Tom.

    No, not the engine from the 73. It's one I pulled from the shelf.
  7. Mark Demko

    Mark Demko Well-Known Member

    Amazing for sure!
  8. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    That engine probably had severe detonation issues and was lugged down hard. That distorts the mains over time.
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  9. stk3171

    stk3171 Well-Known Member

    Took a 73 apart and found 4 cap strew rods and 4 bolt and nut rods.
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  10. sean Buick 76

    sean Buick 76 Buick Nut Staff Member

    Yes Dan I’ve seen that too! Not a very well balanced engine!
  11. UNDERDOG350

    UNDERDOG350 350 Buick purestock racer

    I've found them with 2 different rods also but could not be sure it was an original engine. I found that nut/bolt rods are 638 grams and bolt only are 670.

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