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Thick Heads

Buy adding .100 to the deck surface you allow the entire intake  seat to be enclosed by the aluminum material, also allowing the use of "hoops" or fire rings instead of o-rings.
Note on Intake manifolds : when you add .100 inches to your intake and then put it on a standard deck block, you can simple use a intake manifold for a tall block.For BAE ( or Venny or JFR) fuel thick heads(+.100) they did not add material to the intake side, the idea was most teams at the time already had +.100 blocks and lots of +.100 intakes so as the used up the blocks and std heads the +.100" of material simply showed up on new heads (and new blocks were ordered - std) and they didn't need to by new intakes, this then flooded the used market with tall (+.100) blocks.And now when you got a good deal on tall blocks and found a good deal on tall heads you actually need a "+.200" manifold that does not exist.

Your options for a tall bocks are :
1) cut .100 inches off of the block ----and the registers were the sleeves sit also have to go down .100" ( this is the hard part, but can be done by a machine shop )
2) sell or trade for AJPE thick (+.100) heads these are basically the same but Allan Johnson added the material to the intake side to compensate for the extra height, so when you use AJPE  (+.100) heads to a stock height block you use a std intake or when you use his heads on a (+.100) block you use a (+.100) manifold ( with this you do have to add spacers on the manifold ends). Note: There is still exceptions to this.

These chambers are usually designed for 4.187 bore diameters and hold 200+cc volume


valve actually sits below the deck surface , beside the head gasket


Here a standard deck head is shown with part of the seat exposed and reduced in thickness
( which may distort when heated )


Thick heads correct this and allow use of thicker o-rings made from a tube of stainless steel (hoops) instead of SS wire, also there is no break in the ring around the cylinder

  Hoops - T/F Hemi Height Width  
  Standard  .098 .050  
  Tall .100, .105, .110    
  Wide   .058, .060  


Thick head clears valve and seat