Edelbrock 2.055 (30 degree back-cut) testing

Mean416 said
David Vizard is someone I respect. But I don't believe everything that comes out of his mouth as gospel. He's been hustling a bit of snake oil lately.

Taking my statement about reversion a bit further. Reversion, being what it is, also goes back into the intake manifold. You could also argue that the back cut on the intake valve makes reversion easier too. It's not like it just stops at the intake valve.

What is required is pressure wave or pulse tuning. With that we want the exhaust pressure pulse when the exhaust valve opens to do is travel rapidly down the header or exhaust. Log manifolds do not aid this well by virtue of not separating the exhaust ports. When tuning a header and the collector along with a resonator we are trying to get the 3rd or 4th negative pulse traveling back up the header to arrive at the almost closed exhaust valve just prior to the intake valve opening. We want to prevent the positive pressure waves that come back up the exhaust between the negative pressure pulses from getting past the exhaust valve. Granted there will likely be some, but that is what we try to reduce with anti reversion tactics.
Now the negative pulses we eant to let get past the exhaust valve to create negative pressure in the cylinder just prior to and as the intake valve opens. This creates a big pressure difference across the intake valve curtail area as the valve just lifts off its seat. This helps innitiate intake flow into the cylinder even prior to the piston reaching TDC of the exhaust stroke. This getting the intake air mass moving early past the valve and seat helps purge any residual exhaust out the exhaust valve. If the intake and exhaust pressure pulse tuning is correct there should be no or very little reversion.
Regarding what DV teaches, I will listen as a proven resume of about 60 years with clients in Cup Car and F1 proves he knows a thing or two about engines and car setup. He admits he is still learning, but when his knowledge is far advanced from mine, wisdom tells me to be silent and listen.