magnum cracked heads

Magnum Engine Swaps

  1. rbkt65

    rbkt65 FABO Gold Member FABO Gold Member

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    if you found them cracked, would you have them fixed with new seats or replace them? i am getting ready to tear down a 318 and a 360. if repaired,are they just as good as new?thanks in advance.
     
  2. Idaho

    Idaho Well-Known Member

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    To my knowledge the cracks are generally harmless. I'm sure there are exceptions.
    My thought is not to repair them. Run them or replace them with aftermarket heads. I suspect a repair would not last. Just my guess, not from experience. Others will chime in.
     
  3. Mr. Sinister

    Mr. Sinister Devastation Manager FABO Gold Member

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    Rick there are so many magnum 318 and 360s you should still be able to find replacement heads if yours are damaged.
     
  4. rbkt65

    rbkt65 FABO Gold Member FABO Gold Member

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    i have not pulled the engines apart yet. i was just wondering what to do if they are cracked. i see some have the seats replaced and then i see others buy some other kind of heads. a buddy of mine has removed 5 pairs of heads from 318's and all have been cracked. just trying to find another way out if they are cracked.
     
  5. MileHighDart

    MileHighDart Well-Known Member

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    There are probably hundreds of thousands of Magnum powered Dodge trucks out there with cracked heads and they are still on the road running just fine. I think people make a bigger deal out of it than it is.
     
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    • moparmat2000

      moparmat2000 FABO Gold Member FABO Gold Member

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      Engine Quest monster magnum new replacement heads. These have corrected where the cracking issue is. CH318A or CH318B are the part numbers. One is drilled and tapped for a magnum intake, the other is drilled and tapped for an LA intake.
       
      Last edited: Jul 20, 2020
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      • MoparLeo

        MoparLeo NRA PATRON LEVEL LIFE MEMBER FABO Gold Member

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        Hard as hens teeth to find and the price has tripled since the Magazine articles came out saying how great they are. Keep your eyes out Ch318A Magnum specs and CH318B which is drilled for LA intake.
         
      • JDMopar

        JDMopar Well-Known Member

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        EQ no longer makes or sells the CH318B's. :( :BangHead:
         
      • RustyRatRod

        RustyRatRod Lemmie see your b00bs. FABO Gold Member

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        I've seen a LOT and I mean a LOT of people on here say they would run them anyway. Me? No how no way would I run a cast iron head cracked. Cast iron is some funny stuff. It can crack just sittin there. And the thing is, what's to stop it from continuing? Nothing......until and unless it comes to an edge or a hole. Me? Cracked heads would get thrown in the scrap pile.
         
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        • gtsdude

          gtsdude Well-Known Member

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          Rusty is correct, I have a 99 Dakota with a 5.2. Last year it starts missing. #6 had 15lbs compression. Pulled heads off, crack between valves and burnt exhaust valve. Hard to say how long it was cracked but my guess is it didn’t just happen. It was cracked for a while and got worse.
           
        • 66fs

          66fs FABO Gold Member FABO Gold Member

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          They are not all cracked. My 318 magnum heads were not cracked.
           
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          • jrlegacy23

            jrlegacy23 68 Barracuda

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            I have 2 engines. One is a 2001 5.9 with 65,000 miles and the other is a 2001 5.9 with 120,000 miles. Both sets are both cracked, all have 1 cylinder each cracked. All cylinders that were cracked had this sandy colored look to them.
            149032769230_n.jpg?_nc_cat=101&_nc_sid=ae9488&_nc_ohc=wKpiqy-UDYEAX8ev2-I&_nc_ht=scontent-ort2-1.jpg

            100890102651_n.jpg?_nc_cat=101&_nc_sid=ae9488&_nc_ohc=LgBh0_OfrXAAX8L4B3Y&_nc_ht=scontent-ort2-1.jpg

            upload_2020-10-1_21-32-58.png
             
          • MOPAROFFICIAL

            MOPAROFFICIAL FABO Gold Member FABO Gold Member

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            Sooner or later they burn a seat or leak into the water jacket causing temp rise at idle, and with a/c going.
            The psi build and pushes the spring back on the rad cap and fills the overflow up.

            Cracks are cracks, they will lead to a failure at some point.

            To all these people saying to run them "it's no harm"...
            well...I have a set of 302 heads that mag'd cracked that never gave a lick of trouble on the 318 they were on....would any of you buy them and run them...?

            Probably not!
            Most are plenty repairable by pinning them.
            The repairs if done right will last.
             
          • jrlegacy23

            jrlegacy23 68 Barracuda

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            There are 2 types of magnum heads:
            1. The ones that are cracked
            2. The ones that are gonna crack

            If yours were not cracked, they will. It is the sad truth.
             
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            • 66fs

              66fs FABO Gold Member FABO Gold Member

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              My Magnum heads are not cracked. Magged OK. I doubt they will crack unless I overheat them, and that is highly unlikely. You could usually tell LA heads that would be cracked by core shift, or stuck closed exhaust manifold heat valve. My Magnum heads will do light duty: 180 thermostat; and dual exhaust with no heat valve in an A Body.
               
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