Thick Heads

Buy adding .100 to the deck surface you allow the entire intakeĀ Ā 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 areĀ :
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 Ā (+.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 forĀ 4.187 boreĀ diameters andĀ holdĀ 200+ccĀ 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)Ā instead of SS wire, also there is no break in the ring around the cylinder

Ā  Hoops -Ā T/FĀ Hemi Height Width Ā 
Ā  StandardĀ  .098 .050 Ā 
Ā  Tall .100, .105, .110 Ā  Ā 
Ā  Wide Ā  .058, .060 Ā 

Thick head clears valve and seat