Identify Any Unknown Camshaft Without Removing It – Steps & Tips

Identify Any Unknown Camshaft Without Removing It

The camshaft is a crucial yet often overlooked part of your vehicle’s engine. This shaft with egg-shaped lobes regulates the opening and closing of the intake and exhaust valves, controlling when fresh air and fuel enter the cylinder and exhaust gases exit. The camshaft’s specifications like lift, duration, and timing have a huge impact on engine performance and emissions.

But what if you don’t know what camshaft you have or need to identify an unknown cam before finding a suitable replacement? Read on to learn proven methods for accurately identifying camshaft specs without removing the cam from the engine.

What Is a Camshaft and Why Does Identification Matter?

The camshaft is synchronized with the crankshaft and ignition timing to operate the valve train. As the camshaft rotates, the lobes force the lifters, pushrods, and rocker arms to open the valves at precise intervals. The shape and size of the lobes determines critical specifications:

  • Lift – The maximum valve opening, measured in inches or millimeters
  • Duration – The number of degrees the valve is held open
  • Timing – When the valve opens and closes in relation to piston position

Having improper lift, duration, or timing can lead to reduced power, excessive emissions, engine knocking, valve train damage, and poor drivability. Identifying the camshaft allows selecting optimal upgrades for your engine build and ensuring the correct replacement.

Research the Vehicle and Engine Specs

The first step is gathering key details about your vehicle:

  • Make, model, year
  • Engine size, HP/liter
  • Transmission, rear end ratio
  • Factory camshaft specs if available

Resources include the vin number, vehicle registry records, factory service manuals, forums dedicated to your specific car, and knowledge from previous owners.

This information will narrow down the likely camshaft models originally equipped or suitable for your engine. For older engines, written records may not exist – making physical measurements critical.

Locate Camshaft Identification Marks

locate camshaft identification marks

Inspect the camshaft closely for distinguishing marks stamped or cast into the metal:

  • Manufacturing part number
  • Engineering code
  • Production sequence number
  • Supplier logo

Marks are often found on the front journal or first cam lobe. Use a mirror to inspect without cam removal. Check online resources to cross-reference any identification numbers found.

Some cams lack markings due to wear or just minimal factory labeling. Unmarked or damaged cams will need to be measured to determine specifications.

Use a Dial Indicator to Measure Lift and Duration

The lift and duration specifications can be measured accurately with a dial indicator while the engine is still assembled.

Measuring Lift

  1. Remove the valve cover and spark plugs. Rotate until the lifter is at the base circle of the cam lobe.
  2. Mount the dial indicator so it contacts the very top of the valve retainer. Zero the dial.
  3. Slowly rotate the crankshaft clockwise through the cam lobe profile. Note the maximum indicator reading – this is the valve lift.
  4. Repeat for all lobes – intake/exhaust, front/rear cylinders. Compare readings.

Measuring Duration

  1. Rotate to maximum lift point as determined above.
  2. Set dial indicator back to zero without changing position. Rotate crankshaft in opposite direction.
  3. Note dial reading when lifter first moves off base circle – this is the opening duration.
  4. Continue rotating until closing duration point is reached before lowering again.

Compare total [email protected]” lift to duration specs in camshaft catalogs to estimate duration range.

Degree the Camshaft

“Degreeing” reveals when valve opening/closing events occur in relation to the piston position. It requires adding a degree wheel:

  1. Establish reliable Top Dead Center using a dial indicator in the spark plug hole.
  2. Install degree wheel, follow instructions to set at TDC mark.
  3. Note the angles on the wheel when each valve just starts to open and finishes closing.
  4. Advance/retard cam gear position to optimize for performance goals.

Repeat for multiple intake and exhaust lobes. Compare to known cam degree values to identify grind profile.

Research Lift, Duration and Timing Specs

Use the measurements and degreeing details to precisely calculate lift, duration, and timing. Research specifications for OEM and aftermarket cams to find a close or exact match.

  • Online databases from cam manufacturers
  • Forums with compiled cam spec lists
  • Catalog scans – print or digital

If you can’t pinpoint the exact camshaft, try to narrow it down to a range of grinds optimal for your engine.

Test Performance with Bolt-On Parts

Observe changes from cheap bolt-on mods to help determine the camshaft profile:

  • Carb/intake spacers – Changes in idle vacuum, power gains hint at aggressive cam.
  • Intake manifolds – Compatibility and gains point to stock or tuned cam specs.
  • Tuning changes – Power loss from too much timing suggests wild cam needing less advance.
  • Emissions – HC/CO levels indicate cam duration and overlap characteristics.

Make careful observations before and after changes to validate cam profile.

When to Remove the Camshaft?

If still unsure after above steps, removing the camshaft may be required to get definite identification. This lets you:

  • Visually inspect lobes for wear patterns indicating lift.
  • Take precise lobe measurements with micrometers.
  • Look for hidden casting numbers.
  • Determine exact cam specs and origin.

However, cam removal is time consuming and requires re-timing the cam/crank gear positions. Attempt only after exhausting all other identification techniques first.

Choosing a Replacement Camshaft

choosing a replacement camshaft

Once properly identified, select a new camshaft matching your engine goals:

  • Street performance – moderate lift, duration, low-end torque.
  • Race use – high lift cams beyond 0.600”, long duration over 280 degrees.
  • Towing – higher lift intake side, under 0.600” total.
  • Low-rpm torque – narrow 108-112 lobe separation.
  • Higher rpm power – wide 114-116 lobe separation.
  • Emissions/MPG – Low overlap under 104 degrees, reduced duration.

Talk to camshaft suppliers to select the optimal material, grinding process, and coatings for your specific application.

When to Seek Professional Help?

While identifying a camshaft is possible as a DIY project, consider seeking help from a professional engine builder or machine shop if:

  • You don’t have the specialty tools like dial indicators, degree wheels etc. Renting or buying these just for one use may not be cost effective.
  • The camshaft cannot be degreed properly due to lack of dowel pin in the cam sprocket or flywheel. Precise timing readings require these.
  • The identification numbers are worn off and measurements are inconclusive even after much work. Fresh eyes may spot something you missed.
  • You don’t have the experience performing the measurements and interpretation of the results. Improper technique can lead to incorrect specs.
  • The camshaft needs to be removed for further inspection. This increases the risk of damaging components if not done properly.

The cost is well worth avoiding potential engine damage or choosing the wrong camshaft profile from incorrect DIY identification.

How Much Does Professional Identification Cost?

Expect to pay $200 – $800 or more for professional camshaft identification services from an automotive machine shop or engine builder. Here are typical factors affecting the cost:

  • Whether camshaft removal/reinstall is required – Adds several hours labor.
  • Extensive measurement and degreeing work needed – More time equals more cost.
  • Highly complex engines like vintage overhead cam designs – More specialized knowledge needed.
  • Local labor rates – Big city shops charge more hourly.
  • Shop reputation and expertise – Renowned builders often command premium pricing.
  • Rush orders – Expect higher fees for fast turnaround.

While not cheap, having a pro identify and spec the camshaft with precision tools, experience, and resources is often money well spent compared to damaging the engine with the wrong cam profile.

Summary of Camshaft Identification Steps

  • Research vehicle/engine details to estimate original specs
  • Look for identification markings stamped on cam
  • Measure lift and duration with dial indicator
  • Degree camshaft to determine timing events
  • Cross-reference measured results to identify specs
  • Test performance changes from simple bolt-ons
  • Remove camshaft only if absolutely needed
  • Choose optimal camshaft profile and design for goals

Properly identifying an unknown camshaft takes patience and meticulous work. But the ability to select perfect aftermarket upgrades or replacement cams gives your engine the best performance, efficiency, and durability possible. Let me know if you have any other questions!

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