Cylinder head flow - What is crucial in a stocker?

[HP HUNTER]

Originally Posted by Chipper Chapman

I realize that most stock eliminator engines don’t have what we would call “high” amounts of valve lift. But my question is, considering the amount of dwell at maximum lifts due to our day long durations, where is improving the flow and velocity more crucial? Is it low lift, .100-.300 or what we’ll call higher lift of .350 and up? Typical engines we would not consider maximum max lift flow numbers for much more than bragging rights, and would consider the low and mid lift to be more important as the valve passes through that area twice, which yes it still does, albeit extremely fast. Obviously improving it everywhere is the best case, but often what improves low lift can hurt the high lift and vice versa. So what is the more critical area of improvement in these situations?

I will answer your question: My stocker combination also had .398 lift @ the valve. I dyno tested my engine as it came out of the car 474 HP @ 5400 RPM. I re rung the short block and turned my attention to the heads and intake. I focused on the .200 .300 .400 lift flow and made a nice gain. The engine went back on the dyno, I now had had 513 HP @ 5700-6000. In the real world that HP increase picked my car up exactly 3.2 MPH.
A BBC oval port head with either .398 or .460 lift @ the valve will require either welding the intake seat or Intake valve seats to do what your trying to do, as cast the bowl is too big for a 2.070 valve, which destroys low lift flow.



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