Camshaft Selection

[Greg Hermann]

>-> If you wanna spend a bit of money, and want more bottom end than you
>-> have now, and also a bunch more top end, convert the puppy to
>-> hydraulic rollers, with a rather short duration, but moderate lift
>-> cam, with fairly wide lobe centers. Maybe 202/208 @ .050", .470/.485
>-> lift, (I , then e in both cases) with 112 degree lobe centers.
>
> Those duration and lobe center numbers are right in there for stock
>flat tappet cams.  All you've done is increase lift, which could be done
>more cheaply by swapping to high ratio rockers if available.

Agreed that high ratio rockers would increase lift and valve velocities,
but the rollers also have the potential to increase the area under the
flanks of the valve curve --and number of degrees fairly close to the max
lift -- even more than the high ratio rockers can.

That was the whole idea of these specs. get valve timing about like a
stocker, but area under the valve curves more like what you would get with,
say, a Comp Cams 260 H, flat tappet cam. Without the screwing around with
the funny lifters. Why--low end depends pretty much on timing, mid range
depends a lot more on area under the valve lift curve.

I was prolly guilty of assuming that high ratio rackers would be part of
the deal without saying so.

Also should point out that you would prolly need valve springs good for ,
mebbe, 6500 rpm with a more normal cam in order to not float the valves at
4800 with this type of a cam.

Regards, Greg
>
>
>->  A hydraulic roller grind with numbers
>-> like this would prolly break U-joints at will in the lower gears with
>
> It "prolly" wouldn't, unless the engine was strong enough to perform
>these feats with the stock cam.
>
>==dave.williams at chaos.lrk.ar.us======================================
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