SBM Edelbrock/Speedmaster Head Data

The problem isn’t really in the bulk of the cnc “porting”…….., it’s detail work in the seat and bowl area, and how well that transition is sorted out.

And the fact is, it takes expensive machines, with operators given ample time to get that transition done right.
When you’re building a product around a low price point, that just doesn’t fit into the equation.
So, what you get instead is a blown out bowl that can be made to mate up with a way less than optimal ootb valve seat shape.
Once the valve has been opened up enough to get clear of the influence from the seat, the cnc work done upstream finally starts to reveal itself.
Which, in EA’s example is after .450” lift.

Without getting into too much detail and derailng this thread, an example of what I’m talking about are these results from a CNC ported BBM head.
Without doing any work other than in the immediate seat/bowl area(no additional porting in the runners), by implementing a more air flow friendly seat profile, adding a small back cut to the valve, and blending away a little ridge around the OD of the valve job I was able to pick up:
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With basically zero gain in runner volume.