Camshaft lobe design

[Motor Daddy]

We need look no further than the time when man thought the sun revolved around the Earth. Man experienced the sun "rising and setting" everyday. The effect was perceived as "the same", but the understanding was out in right field. Experience is important, but nowhere near as important as understanding, as far as I'm concerned.

How and why something works is much more important to me than the actual numbers.

$.02

[Windsor377]

Yet the actual numbers prove the earth circles the sun and that the earth is round.

Perhaps, it's more a matter of understanding and perspective being correct.

[Motor Daddy]

Yet the actual numbers prove the earth circles the sun and that the earth is round.

Perhaps, it's more a matter of understanding and perspective being correct.

Actually, it doesn't require numbers, only a view from a distance.

[Windsor377]

Yet the actual numbers prove the earth circles the sun and that the earth is round.

Perhaps, it's more a matter of understanding and perspective being correct.

Actually, it doesn't require numbers, only a view from a distance.

LOL !

[MadBill]

As the saying goes: "You can't see the picture when you're inside the frame."

[jimivice]

I do not mean to insult anyone on this sight. I have used Harold's cams from his Comp. days and have had great success. I have not used Camkings grinds because I have not had the opportunity but he is very knowledgeable. I'm a grunt in the performance industry, but I'm not stupid. I have degreed many a cams in my day and a majority of them have not matched the cam card. It is almost impossible to get the degree specs. to match the cam card-if you adhere to the timing events. Camgrinders can accurately grind a cam with their latest equipment, but you are installing them in production blocks or aftermarket blocks assuming the lifter is at the proper bank angle. If the lifter bore is off by the slightest amount - timing events will change. The opening event might be spot on but the closing might be off a degree or two, or "vice- a -versa". This does not mean, throw away the cam card. In a majority of applications the centerline method is the most accurate, reguardless of inconsistencies of the lifter bore angle, peak lift is not effected. If you do the math, following the specs, it will jive. I allways back up the timing events with the centerline method. I at one time condemned the cam manufacture, but then I realized it was not a problem with the cam manufacturer. I'm not absolving the cam manufacturer from all liability but most problems accur from expectation.

[David Redszus]

Has anyone seen the hollow shaft, powdered metal lobe camshaft designs?
The shafts are ground on what looks like a wrist pin grinding machine. The powdered metal lobes are pressure formed to near net size and shrunk fit onto the shaft at any position or index desired. The lobes are ultra hard but the shafts are softer and tougher. And they feed oil through them. The larger diameter tubes are much stiffer than solid core camshafts and up to 45% lighter in weight.

And how about the CamInCam design which features two camshafts positioned around a center shaft. It provides the adjustability and tunability of a twin OHC cam design but will fit into a pushrod valley. So now, all those pushrod engines can now be retrofitted into twin cams.

Or how about the chromium nitride PVD ring faces with DLC on the flats to reduce ring/piston friction and microwelding. Multilayered plasma deposition is now common as well. They are razor thin, ultra low friction and will seat with a minumum of gas pressure.

Or maybe the new steel top pistons with aluminum pin bores. I can't say skirts since there aren't any. The new designs use diagonal bracing and are ultra light; as much as 25% lighter than any made before. These can run all day and night at combustion pressures of 320 BAR (4700psi).

They use conical wrist pins and don't need gas pits.

[CamKing]

Has anyone seen the hollow shaft, powdered metal lobe camshaft designs?

The current Cup cams are solid powdered metal.
I remember when they started making the pressed on lobe cams. I thought it would be great for flat tappet cams to be able to run lobes made out of a material compatable with the lifters, and the journals can be out of a different material that'll work with the roller bearings.

[novadude]

The cup cams are P/M? The entire cam?

If this works, I wonder why street FT cams have not gone this route? I would think that P/M material that would be hard enough for a lobe would be quite brittle. Can you elaborate on the material / cam blank design?

[CamKing]

The cup cams are P/M? The entire cam?

Yes.
All but the dist gear. The powdered metal is to hard to hobb a gear on it.
The cams are solid(no gun drilling).
They take a special grinding wheel to grind the lobes and journals, and it grinds like krap. If you get any temp in it while grinding, it gets surface cracks. The cams are very expensive, and hard to work with.
I don't even think it's the best option for Cup, but that's what they're using.

[UDHarold]

Windsor377,

That duration growth is caused by changes in the base circle diameter, and even from changes in the roller wheel diameter.
Almost all models and masters in the old days were made on SBC base circle diameters, because the process was costly enough that most companies did not want to cut seperate masters for each engine.
The models are cut by cuttiing the path of the roller wheel axle around the base circle and then the lift curve is added. This produces a pressure angle between the roller wheel and the cam curve. If you could see the lift curve sideways, the point of contact between the roller wheel and the lift curve is at an angle, or the pressure angle, and not on the center of the lifter bore. If the angle gets too sharp(over 30*), the lifter is being pushed sideways in the lifter bore, and sometimes causes lifter destruction.
Changing either the base circle diameter or the roller wheel diameter changes the pressure angle, and causes the duration to appear to change.
I have never seen any BHP change running a small base circle cam instead of a normal one in a SBC, yet there is an apparent duration change on the cam.
I think it is in how we understand cams, vs how the engine does.

UDHarold

PS---To answer your question, no. You would have to measure the same cam grind in a variety of base circle diameters, and construct a graph. It is about 2*(I measured 1.6* in tests) from SBC to BBC, and about 3* with Fords.

[OldSStroker]

The cup cams are P/M? The entire cam?

If this works, I wonder why street FT cams have not gone this route? I would think that P/M material that would be hard enough for a lobe would be quite brittle. Can you elaborate on the material / cam blank design?

Race Engine Technology magazine had a thing on Cup cams a few issues ago. They mentioned the "tool steel" cams made from powdered metal technology. There was a nice sidebar about the material.

One of the companies that developed PM cutting tools for machining was Crucible. Their trade name was CPM or Crucible Particle Metallurgy. We have used CPM tools for machining for 25+ years.

I believe Crucible might be one of the Cup PM cam blank suppliers, or at least their material. It would not surprise me if other companies are also doiing tool steel PM (TS/PM) cores.

One of the nice things about TS/PM is that you can use about any grade of tool steel like the H (Hot work) or S (shock resisting) grades. I'm not privy to what grades are used, but one of the S grades might be a reasonable choice.

These grades are normally thru-hardened, so I suspect that is what is done to the cams. TS/PM, at least in cutting tools, has much better grindability than wrought (rolled or drawn) tool steels of the same grade. It still isn't nice to grind, and you need to use the correct wheels, feeds, speeds and coolants, and you can still burn or get grinding cracks, but I think PM it makes it possible to use tool steels.

My guess is that TS/PM cores may be more readily available than the stellite-welded cores used previously, and they might even be more consistantly durable. This is just coming from a manufacturer's point of view. I don't work in that industry. When I heard of the idea a while ago I thought it was a good one. Evidently it is working.


Jon

[CamKing]

My guess is that TS/PM cores may be more readily available than the stellite-welded cores used previously, and they might even be more consistantly durable. This is just coming from a manufacturer's point of view. I don't work in that industry. When I heard of the idea a while ago I thought it was a good one. Evidently it is working.

The stellite welded cams were barely lasting 700 miles in the cup engines, and teams had been looking for something to replace it for at least 10 years. I had a steel core that held up, but it had to be heat treated after it was ground, and the teams wanted something that could be ground one day and running in the engine the next.
I hate grinding the powdered metal cams, but I haven't seen any dependability issues with them.

[Windsor377]

Windsor377,

That duration growth is caused by changes in the base circle diameter, and even from changes in the roller wheel diameter.
Almost all models and masters in the old days were made on SBC base circle diameters, because the process was costly enough that most companies did not want to cut seperate masters for each engine.
The models are cut by cuttiing the path of the roller wheel axle around the base circle and then the lift curve is added. This produces a pressure angle between the roller wheel and the cam curve. If you could see the lift curve sideways, the point of contact between the roller wheel and the lift curve is at an angle, or the pressure angle, and not on the center of the lifter bore. If the angle gets too sharp(over 30*), the lifter is being pushed sideways in the lifter bore, and sometimes causes lifter destruction.
Changing either the base circle diameter or the roller wheel diameter changes the pressure angle, and causes the duration to appear to change.
I have never seen any BHP change running a small base circle cam instead of a normal one in a SBC, yet there is an apparent duration change on the cam.
I think it is in how we understand cams, vs how the engine does.

UDHarold

PS---To answer your question, no. You would have to measure the same cam grind in a variety of base circle diameters, and construct a graph. It is about 2*(I measured 1.6* in tests) from SBC to BBC, and about 3* with Fords.

Thank you for your insight Harold. I was hoping I could put an easy algorithm on it, but thought I was wishing for too much.

Over the years I've had to juggle this growth and usually it's just a couple - few degrees. One lobe that seems to grow a lot is your old R74 lobe that I like to mix with your old NR100 lobe in PG tranny cars.

The NR 100 grows 2* and the R74 grows 8* and runs like an SOB when matched together.

I need to try some of your new stuff coming off the Landis.

Thanks again,
Henry

[David Redszus]

The stellite welded cams were barely lasting 700 miles in the cup engines, and teams had been looking for something to replace it for at least 10 years.

Mike
What has been your experience with chilled cast iron? We used them many years ago but have become hard to find. Perhaps you have a source for cores.

Used with chilled cast iron finger follower pads, they both lasted forever. Maybe thats the problem.