Newman cams

weaker and less stiff are not quite the same properties.

Cast iron does have about half the Youngs Modulus (elasticity) of mild steel, so it IS less flexible than a steel equivalent.
But in the short length and the thickness of a norton cam, the differences are only going to be minute,
that extra 1 or 2 bhp sounds dubious. ?

I have supported both a PW3 chilled cast iron cam and stock Norton cam by the bearing journals in my valve spring tester and applied 400 lbs of pressure to the center of the cam. The chilled cast cam deflected almost twice as far as the stock cam.

It was a solid core stock cam that I tested.

Chilled iron does make a good wear surface for the lifter. The hard surface is not as thick as a conventionally hardened steel cam. Jim

Both were solid cores that you tested ?

May we ask how much they deflected ?
And how much a 400 lb load is, compared to normal use - of the valve spring types that you use ?

Rohan said:

Both were solid cores that you tested ?

May we ask how much they deflected ?
And how much a 400 lb load is, compared to normal use - of the valve spring types that you use ?

Click to expand...

Since it was a few weeks ago that I did the first checks and I didn't record the results I went ahead ad did it again with better results.

Here is the setup.
Three cams. One stock Norton solid core cast steel cam, one stock Norton billet hollow core cam, and the chilled cast iron PW3 which is hollow core.





I preloaded each cam to 50 lbs and zeroed the indicator. Then I increased the pressure to 400 lbs.

The solid core cast steel cam deflected .021 in.

The stock Norton hollow core billet cam deflected .027

The chilled iron cam deflected .032

400 lbs was just a number that is comfortably in the range of my valve spring pressure gauge. Probably a little more than normal spring pressure but substantially less that the pressure from inertia as the valve begins to open.

After doing this test and setting down with a cold one I realized I forgot one important thing.
I didn't subtract the defection of the arbor press, linkage and load sensor from the readings.
A check of the flex of the press came out at .016 inch between 50 and 400 lbs. [wow]

So that makes the solid steel cam flex .005
The hollow steel cam .011
And the PW3 cam flex .016

That is much closer to the results I got the first time I was checking with a poorly mounted dial indicator on the cam. Jim

JS
those roller cam followers are indeed very interesting, very similar to those used in Weslake engines.

Do you know the diameter of the rollers?

Running a check on re working a PW3 valve lift design to be compatible with a 0.75 inch diameter roller, the grind wheel radius would have to be 1.815 inch or smaller, because the re design produces a negative radius component on the opening and closing flanks.

Interestingly, a similar re design carried out for the Norris RX reveals that no such negative component exists, and therefore the profile could be ground with a wheel of any size.

I do not know whether Newman Cams have a wheel small enough to grind up a PW3 re designed as above.

I have to say that for a guy named Snotzo you get pretty damn technical!

Glen

Snotzo said:

JS
those roller cam followers are indeed very interesting, very similar to those used in Weslake engines.

Do you know the diameter of the rollers?

Running a check on re working a PW3 valve lift design to be compatible with a 0.75 inch diameter roller, the grind wheel radius would have to be 1.815 inch or smaller, because the re design produces a negative radius component on the opening and closing flanks.

Interestingly, a similar re design carried out for the Norris RX reveals that no such negative component exists, and therefore the profile could be ground with a wheel of any size.

I do not know whether Newman Cams have a wheel small enough to grind up a PW3 re designed as above.

Click to expand...

I don't have any info on the roller lifters - just the photo. Newman has made me a PW3 cam for BSA lifters before (JS2). I'm trying to get the profile data from them. I'll let you know.

Do note that the smaller the diameter of the roller on lobe and the pin/axle of the roller itself can increase the speed of surface translation to turn oil into burning vapors then metal into exploding plasma. 0.75 inch is about as small lifter dia. as small block chevy V8 can get away with.

The thin coatings like the failed DLC one really need to be applied over a hard surface to start with. If the substrate is not hard enough it allows the coating to defelect and fall apart. The other thing to be careful of is that the depth of the contact stress is not at the depth of the interface between the DLC coating and the substrate.