GT40 iron exhuast bowl and thermactor hole

[fidstang]

I had no idea that 1994 cobras had the thermactor pluming that actually went from the back of the exhaust bowl into the intake plenum. WTF! I am porting the heads and noticed this on exhuast bowl number 2. Doesn't this hurt flow? I know that with the fel-pro 1250 gasket kit it comes with the two pieces that block that from going into the lower plenum. Won't those burn up? I don't know if I should look for another set. Will this affect power or more importantly, torque? Do all the GT40 irons have this or am I just one unlucky SOB?
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[fidstang]

This might be a better pic. Click on it for a close up.
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[fidstang]

Anyone? Is this on all GT40 iron heads?

 

[Euphoric306]

i'd check for ya bro but my 95 gt40's still have the valves seated

 

[rd]

Not sure what you are asking here.

Based on my collection of heads, inlcuding some 94 Lightning units, they have the air injection ports from the exhaust bowls to the back of the heads, and the exhaust crossover passages that allow exhaust to warm the intake. These are two separate functions. The small bump with the hole leading to the passage to the ends of each head is air injection system, mean to carry air from the smog pump to the exhaust ports to facilitate complete combustion.

As far as I know, yes, you can block of the "heat riser" passages from the exhaust to the intake, and it is ok to grind out the "thermactor bumps" in the exhaust ports smooth with the port roof.

 

[fidstang]

Thanks, I was wondering about the heat riser. Didn't know what it was called or did! How sould I go about porting that bowl and area?