Cam Lobe Images. Comments Please.

[David Redszus]

That part I understand but thanks for laying out the math for better explanation.
I think I failed to explain properly what I was thinking.
If you have 2 springs with 250 lbs seat pressure which is what everyone seems to focus on but one has a 500 spring rate and the other has a 650 spring rate, even though they both have the same seat pressure the 650 rate spring will greatly increase side load and ware. I hope that makes since.

OK, lets look at what you have proposed.
If both springs produce 250 lbs seat FORCE, then the 500 lb/in spring must deflect .5" at installed height, and the 650 lb/in spring must deflect .385" at installed height.

If both have the same valve lift (0.5"), the 500 lb/in spring will produce a nose FORCE of 500 lbs, and the 650 lb/in spring will result in a nose FORCE of 575 lbs.

The side force produced is a function of FORCE, friction coefficient, and pressure angle. Assuming both have identical Mu values and pressure angles, then the side FORCE is determined only by the nose FORCES; 500 and 575 lbs.

Therefore the 650 lb/in spring will result in a side force that is 15% greater (575/500) than the 500 lb/in spring.

But wear is not just a function of load; the surface area of the roller follower must be considered. The area of contact between two rollers is a function of material deflection, diameters, and roller width. If the materials, diameters, and roller widths are the same, then the side force is once again the result of nose FORCES.

[GARY C]

David, thanks for taking the time to lay that out, it was something I noticed when search lobes from Comp and I noticed on their less aggressive lobes this was one of their recommendations. It was more of the open pressure and spring rate that caught my eye, I would have thought the more aggressive lobe would have called for more. EDIT! I forgot to mention that it was recommended that the first spring be shimmed to 230lbs seat but then at half lift that puts you 68lbs over the lower spring which made me think about seat pressure quoted #'s not telling the whole picture.
Dual Valve Springs
I.D. of Outer Dia.: 1.114"
I.D. of Inner Dia.: .724"
Seat load: 215lbs @1.900''
Open load: 690lbs @1.150''
Coil bind: 1.090''
Rate: 633lbs/in
With damper
http://www.jegs.com/i/Comp-Cams/249/999-16/10002/-1

But on their most aggressive TK lobe this was their recommendation.
Duel Valve Springs
I.D. of Outer Dia.: 1.136"
I.D. of Inner Dia.: .812"
Seat load: 230lbs @2.000''
Open load: 580lbs @1.300''
Coil bind: 1.230''
Rate: 500lbs/in
Without damper
http://www.jegs.com/i/Comp-Cams/249/26089-16/10002/-1

[Walter R. Malik]

I mean a roller is supposed to roll over the surface and not glide over it.

Actually, if you look at the acceleration rate of most racing roller cams, you will see that it's well above the rate the roller bearing can accelerate.
All mechanical rollers skid on the opening flank of the lobe.

A REV-KIT helps this situation, does it not?
I always thought they had little to do with actual RPM increase but, keeping the roller wheel in contact with the lobe was its job.

[F-BIRD'88]

What the rev kit does is reduce shock on the roller bearing
when the lash is taken up each cycle.. Made all worse if the racing cam lobe lacks a functional lash ramp on the opening side, cause either the lash is set too big or the lobe lacks a ramp or both.

I don't believe that the roller slows rotational speed at all
during the lash period. The only change is the acellerating change in cam speed as the engine rpm accelerates.
cam is 1/2 that speed... That change in speed of the cam
of each rotation that occurs during the lash period of each cam rotation is small. The big gain of the rev kit is less shock
by keeping the rollrr bearing loaded full time.
Roller bearings do not like shock. Neither do hockey sticks nor baseball bats.

[F-BIRD'88]

It does also add some control and anti serge anti vibration
to the system. But if the rev kit spring is wrong it can add to a
resonant vibration and make serge worse at a critical frequency. (rpm point).

[F-BIRD'88]

lifter shock also pounds the lifter bore with a rollers side load.
Shock is bad.

[F-BIRD'88]

A axillary spring mounted above or near the push rod side of the rocker arm between that point and the under side of the valve cover or a brace bracket structure would keep the whole pushrod side of the valvetrain loaded eliminatibg any lash on that side of thr rocker arm.. Less lash shock on the roller bearing, better motion control. One spring dampens the harmonics and serge of the other.
The running applyed load on that pushrod side control spring could be varied with rpm. Now the only point of lash is between the valve tip and rocker tip.

[F-BIRD'88]

Both roller bearing wear and internal slop and excessive
running valve lash (or insificiant valve lash) should be able to be detected
by acoustic sensors on the valvetrain.
The acoustic sound signature could be logged in a data logger and or warn the driver and or control a automatic lvalve lash adjustment system.
That is not a hyd lifter. A different device that does not reach to momentary valvetrain separation (valve toss) nor air in the engine oil.

[F-BIRD'88]

At that point it is simply more practical to move the camshaft in the cylinder head . eg. OHC conversion. sohc or dohc.