Milwaukee Midget

[fordboy628]

I think part of my problem goes to trying to measure every 1* and the inherent difficulty being accurate in the entire process as Fordboy has pointed out. He mentions going to 5/10000" while I am maybe at .05MM accuracy. Big difference. the program I was using will import electronic files as from a Cam Dr or Cam pro so they should be a lot more representative of reality.
 

Measuring every crank degree is every 1/2 degree of cam rotation, which is too small an increment for data measurement by hand.

Additionally, unless you are using an electronic degree wheel with .1 degree resolution and accuracy, your degree measurements are somewhat subjective.   Larger diameter degree wheels help, but any degree wheel with lithographed or printed degree marks, won't always be accurate, all the way around.     And don't get me started about some of the degree wheel pointers I've seen.     It is why I have a sh** fit every time I see cams being degreed with a bent piece of coat hanger . . . . . .
 
Fordboy

[fordboy628]

Here's a thought.

Of course, using an automated, motorized cam checker will always get you the most reliable reading, because it's virtually infinite in its input-output readings.

But one of the other advantages is that it automatically minimizes slack between the fixture and the measuring plunger.

I'm wondering if making a complete revolution of the cam for each degree of measurement might not smooth out the reading. 

There's likely an infinitesimal amount of slack between the cam and the fixture that could be minimized by always coming up on the lobe in the same direction and from an equal distance.

Think torque wrench.

Or think guitar.

On a guitar, you want to tune "up" to the pitch, not take it down.  This keeps the attack of the tolerances constant in the tuning keys with respect to your measurement (pitch of the string). 

If you approach the lobe measurement with the same idea, you would advance the lobe 361 degrees, take your measurement, advance it another 361 degrees, etc., keeping the attack of the tolerances always on the same relative side of the fixture. 

Huge difference?  On an acceleration flank, I think maybe so.

As a former bass player, I get your analogy.

Methinks your proposed solution is too complicated for the accuracy of the tools generally available to the average racer.

Consider this:   The accuracy typically achieved by Cam Drs and Cam Pros comes from three areas.

A)     Accurately made fixtures.
2)     Higher resolution encoders are used.   .1 degree resolution rotary encoders and 50 millions resolution linear encoders.
d)     And lastly, and most importantly: Data averaging.   10 data points per degree are used to average the readings.    This is nothing more than "smoothing" at the data
        accumulation level.

One thing I have noticed is that as I import my older Cam Dr files into P/T's Cam Analyser, the program is notifying me that the data "might" have a "few" bad data points.   Although all the Cam Dr data was accumulated on a fixture with high resolution encoders, I think this is because the original software may have "smoothed" the measurements too much by data averaging.    When the raw data is imported unfiltered into other programs, the data comes under the scrutiny of newer, more powerful software.   Some of the newer cam analysis software data averages at 100 data points per degree . . . . . . .

I think the best solution for hand data accumulation is this:

Measure every 2 crank degrees (or 4 crank degrees) with an high resolution electronic dial indicator.    Using a high resolution linear indicator with less data points allows the software to "data average" upon input.   This at least saves your sanity . . . . . . . .

http://www.amazon.com/Anytime-Tools-digital-electronic-indicator/dp/B001DC96YK/ref=pd_sim_sbs_hi_3?ie=UTF8&refRID=182VEQBS9HBDQNMK4SWN#productDetails

Approx $75 USD.    No doubt available elsewhere.

Use as large a degree wheel as you can fit to your setup, at least 11"/12" diameter.    If you don't, you are just not serious about the measurements.   Some photos:



That engine elf looks familiar . . . . . . .
 
Fordboy

[fordboy628]

Digital cam degree setup:

http://www.summitracing.com/parts/alt-dcam/overview/

This expensive setup reads in tenths of a degree.
 
Fordboy

[fordboy628]

Here is the Altronics YouTube video about using their setup.

https://www.youtube.com/watch?v=cezpD3oxc64

 
Fordboy

[jacksoni]

Here is the Altronics YouTube video about using their setup.

https://www.youtube.com/watch?v=cezpD3oxc64

 
Fordboy

cute gadget. Expensive degree wheel huh?  At least in the video they are assuming a symmetrical lobe- and I think suggested backing up the rotation checking the cam which would screw things up with belt slack stretch/slack etc. However, I assume their directions are more complete. Here is the factory website: http://www.altronicsinc.com/degree-wheel/digicam-digital-engine-degree-wheel-1.html  299.99 plus $30 for each crank insert. They say is nice for in the car checking and I can see that. but you need to pull the damper hub if so, which in my case involves the pump drive, trigger wheel, damper etc.

[Jack Gifford]

"expensive"? Perhaps "over-priced"; I say that after seeing their set of 6 crank inserts @ $150. Another reason for saying that, is that digital electronic consumer items, in general, are becoming extremely cost-effective. I just bought a laser tachometer (3 - 99,999 RPM) for $20.

[fordboy628]

"expensive"? Perhaps "over-priced"; I say that after seeing their set of 6 crank inserts @ $150. Another reason for saying that, is that digital electronic consumer items, in general, are becoming extremely cost-effective. I just bought a laser tachometer (3 - 99,999 RPM) for $20.

Yes, I think it is "overpriced" as well.    I think it is aimed at the "Pro" engine builder segment of the marketplace, where cost is no object.    It is also why I do not have one, although I think the resolution would be a good thing for profiling camshafts.

 
Fordboy

[fordboy628]

I think this is the best compromise between cost and accuracy, for hand data accumulation on cam profiles.

http://www.summitracing.com/parts/mor-62191/overview/

18" diameter Moroso Pro Degree Wheel,  $51.97 + shipping.   If you spend a few more bucks, free shipping . . . . . .  

All of the other large diameter (16") "Pro" degree wheels are priced between $190 and $210 each.   Hence, the $300 price tag for the electronic degree setup.

Yeah, I know it's not digital, but consider this:  18" dia x Pi = 56.54866776 inches divided by 360 (crank) degrees = 0.157079" per crank degree and 0.078539" per cam degree.    That's 5/32" for crank and 5/64" for cam degrees, respectively.   That's a pretty large increment.

With a high resolution digital dial indicator to measure the lift every 2 or 4 crank degrees for input into P/T's Cam Analyzer, I think that is probably the best compromise between cost, accuracy, and complexity for the average guy who can't find a shop to run his cam on a Cam Dr or a Cam Pro or P/T's Cam Test Stand for Cam Analyzer.

You would still need to dial indicate the cam timing in the engine for checking things like valve to piston clearance, but everybody does that anyway, right?  
 
Fordboy

[Jack Gifford]

If I had just slightly more use for it, I wouldn't hesitate to buy a "Digicam" from Summit and disregard my thoughts about "overpriced".

[Rob]

Sir Henry Royce (Rolls Royce) said it best... "The quality is remembered long after the price is forgotten".

[fordboy628]

Sir Henry Royce (Rolls Royce) said it best... "The quality is remembered long after the price is forgotten".

Quality of tools, re: accuracy and repeatability, are way more important than most imagine.

True story.  One of the more knowledgeable SCCA racers I know, started loosing head gaskets on his ride.   Since he did all the work, he was perplexed about the cause, and "blamed" the cause as a "bad batch of head gaskets".   When he changed suppliers and continued to experience problems, I suggested that perhaps his new, shiny torque wrench was the culprit.    He insisted that because it was new, "IT HAD TO BE GOOD" . . . . .

Needless to say, when I took it from him and tested it against a properly calibrated torque wrench (of mine . . .) it was 18 ft/lbs LOW.   He sh** his pants.
 
Fordboy

[WOODY@DDLLC]

And now his pants are calibrated, too! 

TBV: Trust But Verify! 

http://www.summitracing.com/parts/mor-62192/overview/

[Seldom Seen Slim]

Let me go off on a bit of a tangent -- but it's germane to this thread right now.

It has happened a bunch of times that I'll visit a place (say, the doctor's office) where I am to be weighed.  I'll ask about the accuracy of the scale - and get told that "we just did that the other day."  And then I ask how -- and am told how they make sure there's no weight on the scale's footpad and set the "zero" to exactly zero.

That's NOT calibrating, it's merely setting the zero point.  If they want to calibrate they need to put a known weight on the scale and measure it.  And the weight should be in the range  (mid-point is best) of the middle of the scale that's used (i.e. if the scale goes up to 300 they should use a weight that's about 150#). THEN set the zero point - and you'll have those two known points.

Ditto on your torque wrenched and everything else.  I don't know how to calibrate a wrench other than with a torque wrench dyno (or whatever it is called), but there is a method.

Back to you, Mark and Chris.

[Milwaukee Midget]

Ditto on your torque wrenched and everything else.  I don't know how to calibrate a wrench other than with a torque wrench dyno (or whatever it is called), but there is a method.

My drummer (or as he once said, "I'm not your drummer, you're my guitar player") is a Snap-On dealer.  He has a tool for checking TW accuracy on his truck.

Now as to how accurate the tool is, I'm willing to trust him, but I handed him two torque wrenches to check.  The new Craftsman, which I've had for a little over a year, was described as pretty close.  But he handed me back the old SK and said, "And here's your breaker bar".

Which explains the helicoils in the flywheel of the Midget.

[fordboy628]

midget,

Inquiring minds want to know who won the Chili Pepper races at the 13th Annual Rockabilly Chili Fundraiser held in Beerhaven yesterday.

I know that the "Red" pepper appeared to win the 12:00 race.    What about the protest rumor?

Complete Race report please . . . . . .

Chili cook off winners too please, if known.
 
LouiesDemiseboy