For you 351C fans....turn up the volume!!!

[olddog]

Brent,

I heard it claimed that there is nothing you can do to improve the flow on the 4V Cleveland intake port, as it already flows more air than a 351 engine can suck in. You can debate that, but the point is it is already one very good head.

That said the exhaust port has undergone many modifications by racers over the years. So we know the exhaust port has room for improvement. In fact, it is the bottle neck or handy cap of the 4V Cleveland.

So let's talk cams a bit. Back in the day, I don't recall ever seeing more than a degree or two difference in intake and exhaust duration for any engine. Today it is quite common to see more duration on the exhaust. Typically 6 deg split range. I think the Clevland 4V needs very little duration on the intake compared to the exhaust side. Perhaps 220 -225 on the intake and 235-240 on the exhaust.

I know the 4 valve modular 4.6 ltr can make 400 Hp with only 228 deg durration @ 0.050 at about 7K rpm, with a relatively flat torque curve because the heads flow so good. Take that to the intake side of the 4V Cleveland which also flows well, and my theory is that everyone runs too much cam for the intake port.

So if you are playing with a dyno mule, I sure am curious what such a cam would do.