Reply to "434 Dyno"

I think you need more duration. That's less cam than what I ran in a
10:1 Aussie 2V headed 351C with single plane carb and Holley 735. In
my Pantera, that engine would pull 5th gear from just off idle. You've
got a bunch more cubes and a much longer stroke that just begs for more
overlap.

I drove a friend's Superformance Cobra replica with 418W equipped with
AFR 205 heads and Victor Jr intake and a custom Comp hydraulic roller
cam with 244 degrees duration, 0.6" lift and 110 LSA. It was daily
driver easy to drive. Granted it's a light weight Cobra replica but
you could pull away form a dead stop in third gear. That engine made
556 HP on the engine dyno at 5700-5800 RPM. Wih 30 degrees more duration
and fewer cubes than your engine, it was still not a high strung engine.
In fact, the owner switched to the next larger cam.

That Crane is a tiny cam for the cubes and I'd be a little concerned with
pinging once your chambers get carboned up.

If you go to a cam with larger duration, you really don't need the extra
exhaust duration (relative to the intake). On a drag race engine, that
helps scavenging at higher RPM but it hurts you at lower RPM (not good
for fuel economy either). Plus you need a really good exhaust system to
see the high RPM scavenging benefit. The exhaust valve opens about 2/3
of the way down on the power stroke. The pressure is from 200 to 300 PSI.
>90% of all the exhaust gas is *gone* before the piston reaches BDC on the
power stroke. Since the exhaust stroke is doing nothing by then, why
increase its duration at the expense of overlap? Better to stay closer to
single pattern and increase the total duration.

Just adding lift to the cam you have won't make a whole lot of difference.

Dan Jones