Taming the Tick: A Guide to Adjusting Pushrods on Harley Evo Motors

The rhythmic “tick-tock” of a Harley Evo engine is a symphony to some, a nagging concern to others. This signature sound often stems from pushrod adjustments, and for the mechanically inclined, tackling this task can be both empowering and rewarding. But before you dive in, remember: this is not a project for the faint of heart. It requires patience, precision, and a healthy respect for the intricacies of your engine.

Gearing Up:

Before we crank any wrenches, let’s gather the necessary tools:

Service manual: Your Harley’s bible. Refer to it religiously for specific torque values and procedures.
Feeler gauges: A must-have for measuring valve lash (clearance).
Socket set: Invest in a quality set with metric and standard sockets.
Adjustable wrenches: Two sizes should suffice for most adjustments.
Torque wrench: Crucial for ensuring precise tightening to spec.
Pushrod tool: Makes adjusting non-adjustable pushrods easier.
Dial indicator (optional): Provides more accurate valve lash measurement.
Marker pen: Mark pushrods for reference during adjustment.
Patience: This is not a race. Take your time and do it right.

Understanding the Basics:

Evo engines utilize pushrods to transfer camshaft rotation to the rocker arms, opening and closing the valves. Proper adjustment ensures minimal clearance (lash) between the pushrod and rocker arm, preventing excessive noise and wear. Too much lash leads to clatter, while too little can bind the valves, impacting performance and potentially causing damage.

Adjustable vs. Non-Adjustable Pushrods:

Evo models came with both adjustable and non-adjustable pushrods. Adjustable ones offer easier fine-tuning, while non-adjustable require specific lengths for each cylinder. Identify your type before proceeding.

The Process:

1. Preparation:

Warm up the engine: Run it for a few minutes to operating temperature. This expands components for accurate measurements.
Drain the oil: Easier access to the pushrods and prevents oil spills.
Remove the rocker boxes: Follow your service manual for specific steps.

2. Finding TDC:

Rotate the engine: Use the starter or a crankcase turning tool to bring the desired cylinder to Top Dead Center (TDC) on the compression stroke. Refer to your manual for TDC identification methods (timing marks, piston position).

3. Measuring Lash:

Insert the appropriate feeler gauge: Slide it between the rocker arm and pushrod. The gauge should slide with slight resistance.
Record the lash: Note the measurement for each pushrod you adjust.
Consult your manual: It will specify the recommended lash range for your specific model and year.

4. Adjusting Pushrods:

Non-adjustable: Swap out the pushrod with one of the correct length to achieve the desired lash.
Adjustable: Use the pushrod tool or wrench to turn the adjuster until the lash falls within the specified range. Double-check and re-adjust if necessary.

5. Repeat:

Move on to the next cylinder: Rotate the engine to bring the next cylinder to TDC and repeat steps 2-4 for each pushrod.
Double-check: Once all adjustments are done, re-check each pushrod for proper lash.

6. Reassembly:

Install the rocker boxes: Follow your manual’s instructions, ensuring proper torque on all fasteners.
Refill the oil: Use the recommended oil type and quantity for your engine.
Start the engine: Listen for any unusual noises. If necessary, re-adjust the pushrods.

Pro Tips:

Mark the pushrods: Before removing them, mark their position with a pen for easier reinstallation.
Use a dial indicator: If you have one, it can provide more precise lash measurements than feeler gauges.
Take your time: Rushing can lead to mistakes. Be patient and meticulous.
Double-check everything: Before starting the engine, ensure all components are properly installed and torqued.

Safety First:

Always wear safety glasses and gloves.
Work in a well-ventilated area.
Be mindful of hot engine components.
If unsure, consult a qualified mechanic.

Remember:

Adjusting pushrods requires technical knowledge and attention to detail. If you’re unsure about any step, don’t hesitate to seek professional help. With the right tools, information, and a steady hand, you can conquer this task and ensure your Evo engine purrs like a lion, not a rattletrap.