Switching from factory ex manifolds to headers

Discussion in 'Small Block Tech' started by koosh, Apr 15, 2021.

  1. koosh

    koosh Well-Known Member

    So I picked up used 350, typical rusted bolts on ex manifolds. Already snapped 2 bolts....soaking in PB blaster not much help. Propane torch useless.
    It "appears" my headers dont use that long lower center bolt, so I plan to just cut off at the surface. .... anyone with experience with this issue?
    Looks like a lot of drilling out the holes and using bolts and nuts?
     
  2. sean Buick 76

    sean Buick 76 Buick Nut

    Easy, just remove the heads and buy TA alum heads... bolt em on and go
     
  3. Mart

    Mart Gold level member

    You need all the bolt holes. They are threaded.
    Drill them out carefully & centered., Ez-out, re-tap, or install heli-coils if you have to.
    No on the bolt & nut idea.
     
  4. koosh

    koosh Well-Known Member

    Hmmm, if rust spray, and giant wrench wont budge them, how will a skinny easy out do it? I foresee easy outs being snapped also?
     
  5. koosh

    koosh Well-Known Member

    Now that there is funny...."remove the heads" , just snap those bolts too....lol
     
  6. Mart

    Mart Gold level member

    Plan "B". Snap them off if they don't budge, then drill the bolt remains out & re-tap or heli-coil.
    Heads have to come off to fix threads....
     
    Ken Mild likes this.
  7. knucklebusted

    knucklebusted Well-Known Member

    They don't use the long center bolt? Are you sure you have the correct headers? It sounds like you have SB Chevy headers. All Buick headers use the center hole.

    Also, I just went through this. I used MAPP gas torch to get the head around the bolt cherry red and then tapped it with a hammer. None of the original 91K 50 year old bolts broke.
     
    Mark Demko and Max Damage like this.
  8. Max Damage

    Max Damage I'm working on it!

    I broke one. also using MAP and being super cautious. I was able to drill it out and retap in the car due to extreme shenanigans and stubbornness. I made a jig out of 1/8" plate steel that bolted up to the head and made a 5/16" pilot hole which I aligned with the broken bolt. Then I used a right angle drill adapter with a shorty 5/16" drill bit.

    Sean's idea is better for sure.
     
    Mart likes this.
  9. koosh

    koosh Well-Known Member

    The headers are on a 72 Buick motor still in car (bad motor). I just went out to garage and looked again with a mirror, and I'll be damned I cannot find a lower center bolt. Picture attached of the h 20210415_191338.jpg eaders...
     
    knucklebusted likes this.
  10. Max Damage

    Max Damage I'm working on it!

    You'll find it when you go to take them off ;~)
     
    knucklebusted likes this.
  11. koosh

    koosh Well-Known Member

    Will that motor come out with the headers still mounted?
     
  12. Mart

    Mart Gold level member

    Nope.
     
  13. koosh

    koosh Well-Known Member

    Thanks for all the help
     
  14. sean Buick 76

    sean Buick 76 Buick Nut

    I bet someone just didn’t put that Center bolt in.
     
    knucklebusted and Max Damage like this.
  15. knucklebusted

    knucklebusted Well-Known Member

    OK, you have the correct headers. Usually, the center bolt is a slot in the header flange so you can lift it on and off with the bolt already started. They may not have tightened it after install.

    I would definitely put one back in it if it were me. The gasket needs support in that area.
     
    Mark Demko likes this.
  16. sean Buick 76

    sean Buick 76 Buick Nut

    Maybe you can just switch the heads from the other engine?
     
    knucklebusted likes this.
  17. Mart

    Mart Gold level member

    Those are some fancy schmancy valve cover hold down t-bolts. Haven't seen those in many years....:D
     
  18. koosh

    koosh Well-Known Member

    Yes, they add 2hp per unit....
     
    Mart likes this.

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