400 Block Up For Sale Locally

Discussion in 'Engine Topic' started by Bandit723, Oct 12, 2017.

  1. Rich Schmidt

    Rich Schmidt Veteran Member

    Mar 27, 2010
    Denville NJ

    The problem is that you need to find one made before 1976. After that they used soft metal and thin castings that were so bad that the head bolt holes would break out into the cylinder walls while torquing the head bolts down even on a stock rebuild.
  2. Bandit723

    Bandit723 Veteran Member

    Oct 1, 2016
    Waupaca WI
    Ok feeling better about the block i have I am assuming that the third freeze plug would be mid point on the block if it was a newer casting? Did check for cracks on the decks this last rebuild it was good I believe this thing is a 75 stamping but i did not get the suffix code to validate what i did have. it decked a few years back so that is gone.

    Only reason i have questioned the 4 bolt mains on these is coming from other posts on the net. Seems that folks have a take that the caps are weaker because they are thinner. I have also read that the earlier blocks have a higher nickel/chrome content which makes them a stronger block but personally don't know if that is bs or not as well.

    But at the end of the day still looking for a 400 block if needed.

  3. muscl car

    muscl car Veteran Member Lifetime Gold Member

    If you're worried about the structural ability of a 4 bolt 400 block and want it stronger then add this


    Fill the water jacket to just below the freeze plugs and this will physically strengthen the block
  4. Bandit723

    Bandit723 Veteran Member

    Oct 1, 2016
    Waupaca WI
    So how does this stuff help out with the main crank caps? Quoted" The 4 bolts were made from 70-72 and were the best castings out there
  5. muscl car

    muscl car Veteran Member Lifetime Gold Member

    When the filler hardens it strengthens the main web area as that portion of the water jacket now becomes solid thus not allowing any movement / deflection . This now makes the mains much stronger
  6. tom3

    tom3 Veteran Member

    Aug 1, 1999
    Seems like I remember that in 70 those engines were available with a four barrel and higher compression, with the four bolt mains. But look at the main bearing webs and there sure is some thin material holding that crank in there. Some places look to be about 1/8 in thick. Some later engines had two freeze plugs but had a raised boss where the third plug would have been.
  7. muscl car

    muscl car Veteran Member Lifetime Gold Member

  8. muscl car

    muscl car Veteran Member Lifetime Gold Member

    That's why you would use ceramic block filler to just under the freeze plugs or partial fill . also using a main stud girdle or even billet cross bolt main caps

    All of these options eliminate cap walk
  9. Rdobbs1977

    Rdobbs1977 Huge Guns N Roses Fan

    Dec 1, 2014
    main cap stud girdle is eres on the side of snake oil to me. I don't know that the OP has said what he's wanting to run out of the 400. If for street use, i'd not worry about a 400's integrity. If i was really going to push things out of a motor, splayed or 4 bolt caps would be the path. stud girdle for them...not buying it. jmo
  10. Bandit723

    Bandit723 Veteran Member

    Oct 1, 2016
    Waupaca WI
    I do run a roots blower on this but the main use of the motor is mostly or 90% just moderate driving "street use" but saying that i do let this thing loose and this engine does spin up quick so yes i do worry about the 4 bolt caps not holding or flexing would make for a short lived engine IMO.

    From the sounds of it the 4 bolt mains can be shored up or better ones purchased "adds a little bit of a cost to the block" but not on the machining side. a line bore costs the same regardless.

    My only intent here is to be able to have a good block on hand should i need it. With this car i don't foresee doing some type of LS conversion so a newer gen or block is not in the future but still am looking for a good 400 block i do like these.

    I did run out and look at the second 400. The cylinders where the head was removed was heavily rusted kinda ticks me off for whatever reason that this thing was even listed even though he has an unusable block that he is demanding to get out of his garage. To say the least was a quick meeting.

    Search goes on....
    muscl car likes this.

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