This is exactly the opposite of what is true. Better flowing heads or smaller cubic inches need wider lobe seperations and engines with poorer head flow or more cubes need a narrower lobe seperation angle. However, so you don't just have to take my work for it, there's a chart printed out in the March 2002 Muscle Mustangs and Fast Fords in the article dealing with Bennett Heads. Bennett reccomends the cam lobe seperation angles to use with thier heads on race engines of various sizes and compression ratios. I'll print it out as it's very informative.Small engines with big ports LOVE tight lobe seperations, large engines with small ports work better with wider angles between the lobes.
Bennet is referring to heads (his) that are perfectly matched to the particular racing engine at hand. If a cylinder head is overly large for the particular engine, a tight lobe seperation (along with a free exhaust) will help pick up velocity. Looking at all the drag racing cam profiles for the 4bbl 351C Ford in various catalogs, one will notice that they have tighter lobe seperation angles than comparable Chevy grinds.
Mike. Super Stock rules force them to run with stock unported heads and only a 3 angle valve job is allowed. The engines are spun high and the port velocities are very high, because of the stock production port sizes and the high engine rpm, so it's reasonable that a narrow lobe seperation would be needed. It's exactly what I would predict.Once a combination is optimized to a perfect balance and matched to a certain custom cylinder head (such as Bennet creates) a person can fine tune the angle. A certain Super Stocker I know runs and EXTREMELY tight lobe seperation... and that's with a 289, which is opposite of what you predict. And this LSA was determined after TONS of trial and error on the dyno. It all depends upon the combination.
What works for Bennet, on his custom heads and engines may or may not work for the rest of us.
Porting has been allowed in super stock for years now. They are allowed 155cc with a 289 head (stock is 126). They are also allowed to use Motorsport blocks and aftermarket rods as well... but they must still use the stock compression ratio.Mike. Super Stock rules force them to run with stock unported heads and only a 3 angle valve job is allowed.
It doesn't matter who builds the heads, or if they are custom or not. Bennett works within the same boundaries layed out by the laws of physics as the rest of us. What works for Bennett works for the rest of the world as well. Airflow and engine dynamics aren't affected by the name on the valve cover.