Performance Trends, Inc.

Producing Quality Computer Tools for Racers and Engine Builders since 1986

Cam Test Stand for Cam Analyzer

Electronics and Encoders for Recording Cam Lobe Measurements

As Seen on TV's Motorhead Garage     to view clip of show

Our Cam Test Stand is shown below.  It's encoders measure lift to .00004 inches (4 hundredths of one one thousandth of an inch) and cam rotation angle to .036 degrees.

Standard "non-motorized" Stand w V Blocks                 Motorized Cam Test Stand mounts cam "on centers"
 

to view the Cam Analyzer software page, the software which runs the Cam Test Stand.

for one customer's experience where measuring a new cam saved a lot of time, money and confusion.  We've had lots of customer's relay similar stories, but Mark put "pen to paper".

Displayed below are 3 screens showing some of the features of the Cam Analyzer when fitted with our Cam Test Stand.

Main Screen when measuring a lobe.  Note that on the main screen, the layout of the cam is displayed so you know exactly which lobe you should be on for the different cylinder numbers, intake and exhaust.  Also note that the lobes are graphed immediately with each measurement so lobes which are "out of line" can be quickly checked again.

 

This comparison report shows critical data for each of the 16 lobes on this cam.

  (Click on image to enlarge it)

 

This graph shows detailed comparison between all lobes on this cam.  You can select to graph only certain lobes or all lobes, and lobes from other cam tests.  You can also select to graph lift, velocity, acceleration, and/or jerk.

  (Click on image to enlarge it)

 

Plus Version of Cam Analyzer

The Plus Version of the Cam Analyzer adds "high tech" several features to our standard program.  Prior to version 3.8, most of these features were only useful if you have the complete Cam Test Stand.  Now with version 4.0, you can use these features on hand measurements (dial indicator and degree wheel), standard profiles created within Cam Analyzer, and from importing several formats of standard cam files (like Cam Dr tm, Cam Pro Plus tm, S96, Andrews, Comp Cams, Doctor Dr).  These Plus features include:

  • Virtual Follower
  • Graph Analyze -  Find Difference Between Lobes
  • Lobe Runout Measurement
  • Minimum Required Flat Tappet Diameter Calculation
  • Comparison Reports, between different cam files (camshafts)  
  • Cam Card report
  • Indexing the rotary encoder based on dowel pin or keyway location
  • Measure lobe Asymmetry
  • 4 more detailed analysis reports
    • Lobe Analysis Report (similar to Don Hubbard's C-PEP report from his "Camshaft reference Handbook")
    • Custom Duration Report
    • Seating Velocity Report
    • Checking Limits Report
  • You can Advance and Retard the cam data after it has been measured
  • Watch an animation of the Virtual Follower to see the contact points move, instantaneous Rocker Arm Ratio, etc.
  • More Advanced Options for special lobes, like lobes with 2 "bumps" or where you want to view base circle measurements, runout, etc.

for complete user's manual PDF, where Plus Features are described in Appendices 4, 5, 6, and 8. 

 

Virtual Follower

The Virtual Follower feature lets you measure the cam on the stand without using the actual follower used with the cam.  You will place the linear encoder's pointer directly on the lobe.  See Figures below.  The advantage is you don't need the actual follower or the bore adapter of the correct size for the follower.  For some valve trains, like Overhead Cam systems with Rocker Arms, the Virtual Follower method is the only method available without installing the cam in the engine or Head.

Using Actual Follower                 Using "Virtual" Follower             V4.0 lets you use most any roller follower, including
                                                with encoder pointer               the .750" diameter Universal Roller, pn: CTSUR750    
               

for a graph showing the significant difference (error) between measuring the lobe with the pointer only, and how the Virtual Follower simulation converts this data into the true Cam Profile

You will enter the measurements for the flat or roller follower, or overhead cam valve train into the program.  The software will calculate the resulting valve lift, instantaneous rocker arm ratio, contact point on the follower, and much more.  The Virtual Follower feature is currently developed for:

  • Flat Tappet Followers (which includes Overhead Cam Direct Acting "Buckets")
  • Roller Followers
  • Overhead Cam Center Pivot Rocker Arm (input screen shown below)
  • Overhead Cam End Pivot Rocker Arm (finger follower, input screen shown below)

 Cam_Stand_Virtual_OHC_End_Pivot_Rocker_Arm.gif (22431 bytes)  (Click on images to enlarge them)

You can select to use the same or different Virtual Followers on the intake versus the exhaust cam lobes.    

Accuracy of Virtual Follower

The graph below indicates the typical accuracy of the Virtual Follower to simulate the actual follower for lift and acceleration.   (Acceleration was included as it magnifies differences between lobes.)  Note that we could have come up with graphs of better accuracy.  We purposely used typical data to show that there will always be some difference between the Virtual Follower results and results measured with the actual follower. 

for a "Graph Analyze - Find Difference Between Lobes" report showing the maximum difference found between these 2 cam measurements (Actual and Virtual Follower).   for a "Lobe Comparison" report showing the difference between these measurements for Tappet Lift, Duration, Lobe Separation, etc.  For most of these critical measurements, the difference is less than 0.5%.  For less critical measurements, like peak accelerations, the difference is typically within 2% to 5%.

  (Click on image to enlarge it)

 

Graph Analyze -  Find Difference Between Lobes

If you graph 2 cams, an Analyze option is available called Find Difference Between Lobes.  This option will automatically advance or retard each corresponding lobe of the second cam to obtain the best match, and then display the max difference between the lobes and how much advance and retard was required.  If you have graphed Lift, then the best match for Lift will be found and the max difference in Lift will be displayed.  If Velocity and Acceleration are graphed, then the best match for both Velocity and Acceleration will be found and the max difference in Velocity and Acceleration will be displayed.  

This feature is very useful for finding how a particular cam has changed after running in the engine, if a cam is within legal specs for some racing class, or how similar 2 different cams are.  to see a typical "Find Difference Between Lobes" report for Lobe Lift only for all 16 lobes.  for a comparison of only 2 lobes, #1 Intake and Exhaust Lobe Lift and Acceleration. 

 

Indexing the Rotary Encoder

When you measure a cam on the Cam Test Stand, you must choose where the #1 Intake cylinder's lobe will be installed in the engine, typically based on Intake Lobe Centerline.  All cam data is accurately measured (duration, lobe separation, lift, overlap, accelerations, etc) and the differences between lobes are identified.  However, you would not know if the cam would get installed at this Intake Centerline unless you verified it in the engine.

Note:  With redesigns in the Cam Test Stand, the "TDC Checking Bridge" has now been replaced by the much more compact "Narrow Universal Flat Follower", but the process is much the same.

Now we can measure the dowel pin or keyway location of a cam and know how it is timed in the engine, assuming standard, production timing in the gears.  Using our TDC Checking Bridge, we can precisely measure the dowel pin or keyway location.  Then, knowing how many degrees CW or CCW from TDC it is designed to be, we can index the rotary encoder precisely.  Using this method we can index the cam to better than 0.5 degrees.  (We can provide the "degrees CW or CCW from TDC" data required for this method for many popular engines, but not all engines.)  For engines for which we don't have this data, you may have to work out these settings from known cams.
CTS TDC Checker Bridge 001 Cropped.jpg (185596 bytes) CTS TDC Checker Bridge 004 Cropped.jpg (120111 bytes)  (Click on images to enlarge them)

The TDC Checking Bridge is sold as an accessory, and adjusts to most any length cam from 12 inches to 24 inches in length (measured from first and last journal bearings).  However, you do need the Plus version of the software to access this feature.  Longer Bridges are available at an additional cost.

 

Other Plus Features

Runout is the variation in the base circle radius, where a lower value indicates a higher quality cam.  The Minimum Required Flat Tappet Diameter Calculation is an accepted equation based on peak velocity, where larger velocities require a larger flat tappet follower diameter.  to see the Lobe Runout Measurement and the Minimum Required Flat Tappet Diameter Calculation numbers shown in a Comparison Report.  This Comparison Report (another Plus Feature) is of 2 different cam files, one measured with the actual flat tappet follower and the other using the standard linear encoder pointer and the Virtual Follower feature.

The Cam Card report displays critical, measured cam results commonly found on a cam grinder's cam card, shown below:
cam_Card.gif (18192 bytes)  (Click on image to enlarge it)

New Cam Card Options in v4.0
Cam_Card_v4.0_Features.gif (171260 bytes) (Click on image to enlarge it)

 

Asymmetry Calculation:

 

More Report Types:

for:  Lobe Analysis (similar to Don Hubbard's C-PEP reports from his "Camshaft Reference Manual")

for: Custom Duration (duration, opening, closing, asymmetry at most any cam or valve lift)

for: Seating Velocity (valve closing velocity at user specified RPMs to help pick valve Valve Lash) and estimated lash point

for: Checking Limits (compare a measured lobe to up to 12 specified limits, like duration at various lifts, lobe separation, max lift, etc.)  "Checking Limits" report makes it quick and easy to check if cams are legal for restricted classes of racing, or are meeting certain quality control limits. 

 

 

Cam Grinder Version of Cam Analyzer

The Cam Grinder version is new for v4.0, and adds several features beyond what the Plus version does.  It's features are specially designed for customers who typically grind cams or need to send files to cam grinders for special custom grinds.  The Cam Grinder version also gets into more detailed analysis than the typical customer may need.  These include:

  • Measure cam lobes and keep their absolute timing, and not adjust for lifter bore angle, firing order, etc.  It keeps the absolute timing as is present on the actual camshaft, which is more useful to cam grinders.  See picture below.
  • You can measure absolute lift of the lobes (which will include base circle and runout) and journals if you choose.
  • You have many more graphing options and graph data types, including:
  • Absolute Lift (This is lift measured from the center line of the cam. If you have a 1.100" diameter base circle and a .400" max tappet lift, you should see approximately .550" of lift on base circle and .950" (.550" + .400") of lift at max lift.) 
  • Thrust Angle (For a roller cam, this is the angle the contact force is acting on the follower, typically putting some amount of side loading or thrust on the follower.)
  • Contact Point (How far from center of the follower has the contact point moved.) 
  • Radius of Curvature (The radius of curvature at this particular point on the Actual Cam Profile.)
  • Raw Cam Data as Measured (This is what the linear encoder measured.) 
  • Actual Cam Profile (This is what a "knife edge" pointer would have measured. This is the "Raw Cam Data as Measured" but correcting for the radius of the pointer which was doing the measurements. This should be what a cam grinder would have for a design file.) 
  • Lift Frequency Analysis *
  • Acceleration Frequency Analysis. *
  • Jerk Frequency Analysis *

* These Frequency Analysis graphs can be done either vs Order Number or RPM Based on the Natural Frequency of a valve spring. The specs for the Natural Frequency of the Valve Spring are contained in the Test/Cam Setup Screen. See picture below.

  • Import X and Y data, or polar data (radius, and either radians or degrees) to generate a cam file.
  • Input and calculate a valve spring's natural frequency.
  • Export a Manufacturing type data file.
  • Special Edit and Export Filtering options.

Main Screen Graph showing absolute timing
Cam-Grinder-Cam-Timing.gif (176476 bytes) 
(Click on image to enlarge it)

Graph showing absolute timing and absolute lift for lobes and journals, viewed from end of cam (polar coordinates)
Lobes_and_Journals_Polar_Coordinates.gif (206390 bytes) 
(Click on image to enlarge it)

Graph showing journals with difference exaggerated, viewed from end of cam (polar coordinates)
Journals_Polar_Coordimates.gif (168842 bytes) 
(Click on image to enlarge it)

Cam Grinder Frequency Analysis
Cam_FFT_Frequency_Analysis.gif (127521 bytes) 
(Click on image to enlarge it)

Cam Grinder Graph Options
Cam_Grinder_Graph_Options.gif (148130 bytes) 
(Click on image to enlarge it)

Cam Grinder Edit Duration Option (figures show increasing durations 15% for intake and exhaust) 
Cam-Grinder-Edit-Options.gif (23004 bytes)  Cam-Grinder-Edit-Duration.gif (67702 bytes) (Click on images to enlarge them)

for complete user's manual PDF, where Cam Grinder Features are described in Appendix 6 and 7. 

 

 

What You Get:

  • Cam stand with adjustable V blocks
  • Linear Encoder with sliding adjustable bracket
  • Lifter bore sleeve * and bracket (attaches to Linear Encoder bracket)
  • Rotary Encoder with mounting magnet, sleeve and positioning rod
  • Black Box II data acquisition
  • Power Supply
  • Serial communications cable to computer
  • User's manual
  • Software CD
  • EZ Start Guide

*  Lifter bore sleeve is bored to user's requirements for their lifter size.  Additional Lifter bore sleeves for different size lifters available at additional cost.

 

Accessories:

New Style V Block (2010)                Old Style V Block (pre 2010)
    Part of Part Number:  CTS-UK  Cam Test Stand Update Kit to bring  older CTS up to our current design.  This change allows the linear encoder bracket to slide past the V Block to measure position of keyways and dowel pins.

indexing grove on the vertical rod and  the indexing thumb screw on the CTS-UFH which seats in the groove to keep perpendicular to the cam axis.  Note:  This part number has now been replaced by the CTS-UFHN  Cam Test Stand Narrow Universal Flat Tappet.

 

     Part Number:  CTS-UFHN  Cam Test Stand Narrow Universal Flat Tappet with Indexed Holder, with a 2.0" long x .250" wide flat face.  This setup lets you measure most any flat tappet cam and simulates followers up to 2.0 inches in diameter (the length of the precision .250" plate held perpendicular to the cam).  This can also be used to measure the position of keyways (with CTS-TDCM2  .250" magnet in keyway), or dowel pins.  Note the indexing screw at front of lifter bore bracket, and indexing rod which slides in the slot of the lifter bore to keep things perpendicular to the cam.  The narrow, flat edge allows the follower to ride on timing pins which may stick out of a cam just a few millimeters.  Measuring a timing pin lets you determine the timing of the cam if you know the location of the pin, or lets you measure the location of a pin with respect to a cam centerline.  

for a movie showing how to locate a dowel pin using the now obsolete "TDC bridge".  Using the CTS-UFH instead of the bridge would be very similar.

 


  Part Number: CTS-ML  Locating magnet, keeps cam aligned accurately on V blocks.  Flip down and its out of the way.  Flip up and it keeps cam turning true on the stand.  Magnet slides out of the way if it encounters a dowel pin.  Kit includes magnet, shoulder screw, washer, nylon spacer, template for locating 6-32 hole you drill and tap, and instructions.  for instructions.

  Part Number: CTSUR750  Universal .750" roller follower, lets you measure any cam designed for a .750" diameter roller (typical of most, US V-8 aftermarket rollers).  Sized for a GM .842" ID lifter bore adapter, this includes the follower only and not the lifter bore adapter.

Cam-Test-Stand-V-Block-Clamp.jpg (126028 bytes) Cam-Test-Stand-V-Block-Clamp-Installed-Front.jpg (181473 bytes) Cam-Test-Stand-V-Block-Clamp-Installed-Rear.jpg (244852 bytes) click images to enlarge   Part Number: CTS-VBC  V-Block Clamp, holds short cams firmly on the V Block, shown installed with Adjustable V Block.  Short cams with the linear encoder attached to the end will tend to tip off the V Blocks, and this clamp holds the cam in place.  It has a soft, nylon tip to provide smooth rotation and not damage the journal.

  Part Number: CTS-LEH  Linear Encoder lift handle, provides an easy way to lift the linear encoder probe.  This is especially handy when not using a follower, but measuring the lobe directly for the Virtual Follower feature.

Part Number: CTS-PT Precision 0.047 inch diameter tip for linear encoder.  This is required for measuring very aggressive, inverted flank (concave) profiles.

  Part Number: CTS-EVB  Extended Height V Block Kit, includes 2 V Block Extensions (requires "New Style V Block (2010)" shown above) and extended length Linear Encoder Rod.  This allows for additional clearance for the cam to have a timing gear of or other large diameter (up to 8 inches diameter) component installed.  Other custom heights also available.

  Part Number: CTS-LSRI  Larger diameter rotary encoder index and magnet/bore to accommodate cams with larger than .500" holes in their ends.  NOTE:  Current design of the CTS-LSRI is 1.00" diameter.

  Part Number: CTS-AVB  Adjustable V Block lets you level out the cam when the journal on one end can be significantly different than the other end.  Note:  A slight difference in cam height from end to end (slight slope of the camshaft on the stand) is not critical for most measurements, because the encoder is "zero'd out" by the software for each lobe measurement. 

 

Part Number: CTS-MC  This option adds a motor to turn the cam at a slow, controlled rate, and for mounting the cam "on centers".  This can provide for more accurate measurements, especially for acceleration and jerk measurements.

 

CTS-xxHD-Heavy-Duty-Cam-Test-Stand-Option.jpg (133142 bytes) click image to enlarge   Part Number: CTS-xxHD  Heavy Duty Cam Test Stand option, where xx is the length of the stand in inches.  This option is for very long or very heavy cams which can weigh up to 100 lbs or more.  It includes larger base extrusion, roller bearings instead of V blocks, and other heavy duty brackets.  

 

Ask about other custom options which include:

  • 48 inch long stands for cams up to 44 inch (custom lengths also available)
  • Lifter Bore Adapters to accommodate various lifter diameters (Note lifter diameters greater than approximately 34 mm require a special, larger lifter bore bracket.)

to return to the main Cam Analyzer page.

for prices of the Cam Test Stand and accessories.

for financing info on paying on installments.

for narrated demo movies explaining program features

for info on Cam Test Stand Assembly

for tips on producing repeatable results

 

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