The Harley-Davidson Street Glide's 350 V-Twin engine is a powerhouse, but like any high-performance machine, it requires regular maintenance to keep it running smoothly. One crucial aspect of this maintenance is adjusting the valves, a task that can seem daunting to the uninitiated. But with the right knowledge and tools, you can tackle this task confidently and keep your ride in top condition.
Regular valve adjustment is essential to prevent excessive engine wear, maintain optimal performance, and ensure your Street Glide's longevity. In this comprehensive guide, we'll walk you through the process of adjusting the valves on your 350 V-Twin, providing clear, step-by-step instructions and expert tips along the way.
Understanding Your 350 V-Twin's Valve Train
Before diving into the adjustment process, it's crucial to understand your engine's valve train. The 350 V-Twin features a pushrod-operated overhead valve (OHV) design, with two valves per cylinder - an intake and an exhaust. The pushrods transmit the motion from the camshaft to the valves, opening and closing them in sync with the engine's rotation.
The valves are held closed by valve springs, and their clearance - the gap between the valve and its respective pushrod - is what we'll be adjusting. Too much clearance can cause valve float, leading to noisy operation and reduced performance. Too little clearance can cause valve binding, leading to excessive engine wear and potential damage.
Gathering Your Tools and Materials
Before you begin, make sure you have the following tools and materials on hand:
- Valve adjustment tool (Harley-Davidson part number 99052-91 or equivalent)
- Feeler gauges (set of 0.002" to 0.010" gauges)
- Torque wrench
- Socket wrench
- Pliers
- Rubber mallet
- New valve shims (if required)
- Engine oil and filter (for post-adjustment service)
Preparation: Disassembly and Access
To access the valves, you'll need to remove the engine covers and some other components. Start by draining the engine oil and removing the oil filter. Then, remove the engine covers, spark plugs, and ignition coils. Disconnect the fuel and vacuum lines, and remove the intake manifolds. With these components out of the way, you'll have clear access to the valve covers and rocker arms.
Remove the valve covers, being careful not to lose the small sealing washers. You'll now see the rocker arms and pushrods, which provide access to the valves themselves.
Adjusting the Valves: Step-by-Step
With your tools and materials gathered and the engine disassembled, you're ready to begin the valve adjustment process. Remember, it's essential to work methodically and double-check your measurements to ensure accurate results.
Before adjusting the valves, warm up the engine to operating temperature. This allows the valves to expand to their operating dimensions, providing the most accurate adjustment. After warming up, allow the engine to cool slightly to prevent burns.
Adjusting the Intake Valves
Begin by adjusting the intake valves. Using your valve adjustment tool, compress the valve spring until the pushrod is fully extended. Insert a feeler gauge between the pushrod and the rocker arm. The clearance should be between 0.004" and 0.006". If the clearance is outside this range, you'll need to adjust the valve shim.
To adjust the shim, use a socket wrench to loosen the rocker arm nut slightly. Then, use a rubber mallet to tap the pushrod gently, moving the shim to the desired thickness. Once the correct clearance is achieved, tighten the rocker arm nut to the specified torque (usually around 15-20 ft-lbs for Harley-Davidson applications). Repeat this process for all four intake valves.
Adjusting the Exhaust Valves
Adjusting the exhaust valves follows the same basic process as the intake valves, but with a few key differences. First, the exhaust valves have a different clearance range, typically between 0.007" and 0.009". Second, the exhaust pushrods are often stiffer than the intake pushrods, requiring more force to compress the valve spring.
Begin by compressing the exhaust valve spring and checking the clearance with a feeler gauge. If the clearance is outside the specified range, adjust the shim as described earlier. Once the correct clearance is achieved, tighten the rocker arm nut to the specified torque. Be sure to double-check your measurements and adjustments, as incorrect exhaust valve clearance can lead to serious engine damage.
Reassembly and Final Touches
With the valves adjusted, it's time to reassemble the engine and perform a final service. Begin by reinstalling the valve covers, being sure to use new sealing washers if necessary. Then, reinstall the intake manifolds, fuel and vacuum lines, ignition coils, and spark plugs.
Before refilling the engine with oil, it's a good idea to perform a leak-down test to ensure that the valves are sealing correctly. If the test passes, refill the engine with fresh oil and install a new oil filter. Finally, start the engine and allow it to warm up, checking for any leaks or other issues.
Congratulations, you've successfully adjusted the valves on your 350 V-Twin! Regular valve adjustments are crucial to maintaining your engine's performance and longevity, so be sure to add this task to your regular maintenance schedule. Riding your Street Glide with confidence knowing that its engine is in top condition is a rewarding experience. Happy riding!