Understanding Pushrods in Shovelhead Engines
Pushrods play a critical role in the operation of the Shovelhead engine. They serve as the link between the camshaft and the valve lifters, transmitting the motion needed to open and close the engine's valves. The proper adjustment of pushrods ensures that the engine runs smoothly and efficiently.
Why Adjust Pushrods?
1. Compensate for Wear: Over time, valve seats, lifters, and pushrods themselves can wear down, affecting the overall valve timing.
2. Engine Performance: Incorrectly adjusted pushrods can lead to poor engine performance, misfires, or even engine damage.
3. Noise Reduction: Properly adjusted pushrods help minimize engine noise, contributing to a smoother ride.
4. Prevent Overheating: Valves that do not close properly can lead to overheating and damage to the engine.
Tools Required for Pushrod Adjustment
Before beginning the adjustment process, gather the necessary tools:
- Socket Set: A variety of sockets, particularly 3/8" and 1/2".
- Torque Wrench: For ensuring bolts are tightened to the correct specifications.
- Feeler Gauge: To check pushrod clearance.
- Screwdriver Set: Both flat-head and Phillips for various bolts.
- Adjustable Wrench: For manipulating nuts and bolts.
- Shop Manual: To reference specific torque specs and procedures.
Preparing for the Adjustment
Before diving into the adjustment, ensure the motorcycle is in a safe and stable position:
1. Park on a Level Surface: Ensure the bike is upright and stable.
2. Remove the Seat and Fuel Tank: This will provide access to the engine components.
3. Disconnect the Battery: Safety first; disconnect the negative terminal to prevent electrical shorts.
Identifying the Optimal Pushrod Length
Before adjusting, it’s essential to understand the correct pushrod length for your engine. Shovelhead engines typically use one of two lengths:
- Standard Length: Commonly found in stock configurations.
- Modified Length: Used in performance builds or with aftermarket components.
Refer to your service manual or consult a reputable mechanic if you're unsure about the appropriate length for your specific setup.
Steps to Adjust Shovelhead Pushrods
Follow these detailed steps to adjust your pushrods effectively:
1. Locate the Pushrods
- Remove the pushrod covers carefully to avoid damaging the gaskets.
- Keep a clean workspace to avoid losing small components.
2. Rotate the Engine to the Correct Position
- Rotate the engine to align the timing mark on the flywheel to the "F" (fire) mark on the timing cover.
- This positioning will allow you to adjust the pushrods on the intake and exhaust valves of the cylinder in question.
3. Check Existing Pushrod Clearance
- Using a feeler gauge, measure the clearance between the pushrod and the rocker arm.
- This will give you a baseline to determine how much adjustment is necessary.
4. Adjust the Pushrods
- Loosen the Lock Nut: Using an adjustable wrench, loosen the lock nut on the pushrod.
- Turn the Pushrod: Carefully turn the pushrod to adjust the height. You want a slight resistance when pushing the pushrod down, indicating that the lifter is preloaded.
- Tighten the Lock Nut: Once the desired adjustment is achieved, retighten the lock nut while holding the pushrod in place.
5. Repeat for All Pushrods
- Rotate the engine to adjust the next set of pushrods.
- Follow the same procedure for each pushrod, ensuring that all valves are adjusted appropriately.
Final Checks and Reassembly
Once all pushrods are adjusted, perform the following checks:
- Recheck Clearances: Use the feeler gauge again to ensure all pushrods have the correct clearance.
- Reinstall Pushrod Covers: Carefully replace the pushrod covers and make sure the gaskets are seated correctly to avoid leaks.
- Reconnect the Battery: Reattach the negative terminal of the battery.
Testing the Engine
After reassembly, it’s important to run a test on the engine:
1. Start the Engine: Allow the engine to idle for a few minutes.
2. Listen for Unusual Noises: Pay attention to any ticking or knocking sounds that may indicate improper adjustment.
3. Check for Leaks: Inspect the area around the pushrod covers for any signs of oil leaks.
Common Mistakes to Avoid
1. Over-tightening the Lock Nut: This can lead to damage to the pushrod or rocker arm.
2. Ignoring Wear: Always check the condition of the pushrods and lifters; worn components may need replacement rather than adjustment.
3. Skipping Measurements: Good practice involves always measuring clearances before and after adjustments.
4. Improper Engine Orientation: Ensure the engine is at the correct position for the cylinder you are adjusting; failing to do so can lead to incorrect adjustments.
Conclusion
Adjusting shovelhead pushrods is a fundamental skill for any Shovelhead owner. By following the steps outlined in this article, you can ensure your engine operates smoothly and efficiently. Regular maintenance not only enhances performance but also extends the life of your motorcycle. Always remember that if you're unsure or uncomfortable performing this task, consulting with a professional mechanic is a wise choice. Keeping your Shovelhead in top shape will allow you to enjoy the ride and the iconic roar of the engine for years to come.
Frequently Asked Questions
What is the purpose of adjusting shovelhead pushrods?
Adjusting shovelhead pushrods is essential to ensure proper valve operation, maintain optimal engine performance, and prevent engine wear and damage.
When should I adjust my shovelhead pushrods?
You should adjust your shovelhead pushrods during routine maintenance, when performing a top-end rebuild, or if you notice unusual noises from the engine.
What tools are needed to adjust shovelhead pushrods?
You'll need a feeler gauge, a wrench set, and possibly a pushrod adjustment tool for precise adjustments.
How do I know if my shovelhead pushrods are too tight or too loose?
If the pushrods are too tight, you may hear a ticking noise and experience decreased performance. If they're too loose, you may hear a tapping sound and notice valve lifter clatter.
Can I adjust shovelhead pushrods without removing the rocker boxes?
Yes, you can adjust shovelhead pushrods without removing the rocker boxes by performing the adjustment at the pushrod tubes, but access may be limited.
What should the clearance be for shovelhead pushrods?
The typical clearance for shovelhead pushrods is around 0.006 to 0.008 inches when the engine is cold, but always refer to your specific service manual for exact specifications.
Is it necessary to replace pushrods during adjustment?
No, it is not necessary to replace pushrods during adjustment unless they show signs of wear or damage during inspection.
What common mistakes should I avoid when adjusting shovelhead pushrods?
Common mistakes include not ensuring the engine is at the proper temperature, misreading the feeler gauge, or neglecting to check the adjustment after tightening.
