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1956 Cadillac Heads,

Discussion in 'The Hokey Ass Message Board' started by Blubyu, Oct 15, 2013.

  1. Blubyu
    Joined: Sep 4, 2008
    Posts: 51

    Blubyu
    Member
    from Troy, MI

    :confused:Hey Hambers,
    I recently took apart the 365 in my 1956 Cadillac because of a broken Exhaust manifold. In the process of taking the manifold and head off as one piece I broke the dipstick tube. I already have a new one and the old one has been taken out. I dropped the oil pan and punched it out through the bottom. So I have the driver side head removed cleaned and ready to go back on but I started thinking. The passenger side head is just begging me to take it off and clean it. My question is, Should I rebuild the heads? Put hardened valve seals in and stainless valves? Change the springs? My buddy who I work with in the garage who is somewhat of a master mechanic said that they are fine and leave them alone. Me an anal SOB wants to take them to a good performance shop and have them reconditioned for peak performance. My question is who has done a simple head job to an engine like this, updated it and put a fresh grind. What performance enhancements did you see? Did the car run better? I still use lead additive in the gas. After I had the heads redone I wouldn't have to use lead additive anymore. Any suggestions or advice is what I'm looking for to make a solid decision before I just say screw it and put the car back together this weekend.

    Thanks!
     
  2. Blubyu
    Joined: Sep 4, 2008
    Posts: 51

    Blubyu
    Member
    from Troy, MI

    So far the advice I have received was to port and polish. Open up the exhaust port for breathability and make sure everything is deburred from the casting obstructions. The engine has 110k miles on it. So I guess this would probably be a good time to get this job out of the way. Plus were headed into winter.
     
  3. falconsprint63
    Joined: May 17, 2007
    Posts: 2,358

    falconsprint63
    Member
    from Mayberry

    I'd add the seats and have them rebuilt while you're that far in--or better yet find 390 heads and put them on.
     
  4. Blubyu
    Joined: Sep 4, 2008
    Posts: 51

    Blubyu
    Member
    from Troy, MI

    There is a set of 390 heads online for 900 bucks. Do they make that much of a difference? Time to start studying.
     

  5. 40StudeDude
    Joined: Sep 19, 2002
    Posts: 9,536

    40StudeDude
    Member

    A Cadillac guru of an engine builder here in town (he built the 1970 500" engine in my '55 Cadillac) told me that Cadillac engines have more nickel content than other engines and there is no need to put in hardened seals as the unleaded fuel (w/ethanol) won't harm it.

    FWIW, if it were I, I'd do both heads just to be on the safe side.

    R-
     
  6. My experience with having hard seats installed is that you better be damned sure that your machinist is up to the task. I have seen lots of heads with dropped seats over the years. That said I have seen lots of heads that were trouble free and it was or is a matter of the machinist doing the work.

    As far as performance heads for your caddy unless you are ready to change the cam and up the compression they are a waste. The most I would do or have done is a 3 angle valve job and blend the bowls on a stock mill.

    And as 40StudeDude said and I should have mentioned if I took one head off for a clean up I would also do the other.
     
  7. Blubyu
    Joined: Sep 4, 2008
    Posts: 51

    Blubyu
    Member
    from Troy, MI

    I'm taking the heads to Motor City Muscle it's a shop close by in Clawson Michigan. I have heard from friends that they know exactly what to do with these heads they work on them often. I am not planning on changing any of the other internals on the engine. I mean it would be nice to make it a beast but I just want it more efficient while not going bonkers. The car already drives great! I just want to handle these heads correctly while their at the shop. I don't plan on yanking them again. I would love to get the most HP out of them but I think I'll be satisfied with how well the engines going to function with a fresh Deck and some larger exhaust ports. I plan on driving this car cross country so I'm just freshening up all the components. I've already had the seals on the tranny go on the freeway and other things go wrong just because the car has original parts. It's a museum car so a lot of things that just fail whenever they feel like it. So while I have the engine ripped down I'm trying to handle everything before I seal it back up. So Thanks for the advice on the heads guys. I'm definatley not going at this blindly anymore.
     
  8. falconsprint63
    Joined: May 17, 2007
    Posts: 2,358

    falconsprint63
    Member
    from Mayberry

    390 heads are nice and breath better, but I'm thinking not $900 better. you could pick up a full longblock for less than that.
     

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