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Valve Springs

Valve Springs

Valve springs are as important for the timing as the cams

Valve springs for the V engines from Harley-Davidson, from original replacements to such for performance engines. From manufacturers like Andrews, S&S, Manley and - last but not least - Eibach.

What does a valve spring do?

First of all, and quite simply, it keeps the valve closed in its seat for an undisturbed combustion process. The exhaust valve should remain reliably closed during the intake process while the piston generates a vacuum in the cylinder, which is why the springs for the exhaust valves have always been somewhat stronger. The valve spring also ensures that the valve follows the cam without vibrating or developing a life of its own.

In the early days of motorization the intake valves were automatic, i.e. they were opened by the downward movement of the piston through negative pressure. To prevent them from reacting too sluggishly, they were fitted with comparatively weak valve springs. During the compression, working and exhaust stroke, they were pressed onto their seat by the pressure in the cylinder anyway. That was the theory, but by the 1910s at the latest, it had become clear that it could not be upheld.

More power requires more mixture and an automatic intake valve is not enough to ensure that the engine gets a really good mixture. The intake valves were fitted with a tappet and push rod control and stronger springs.

What are the benefits of stronger valve springs?

The valve spring controls the valve in that it adheres to the timing specified by the cams, tappets, rocker arms, etc. In engines with increased performance, it can happen that the springs no longer fulfill this task. The valve then starts to vibrate at higher engine speeds and constantly lifts off the seat.

This phenomenon is traditionally countered with stronger valve springs. Unfortunately, in our pushrod-controlled Harley-Davidson V engines, this results in more load on the entire valve train. Logical, isn't it? Higher spring force simply means more wear on the pushrod heads and the 20 cm long pushrods also tend to bend under load. If the valves no longer open fully as a result, the stronger valve spring has mutated into a performance brake.

The use of stronger valve springs must therefore be carefully considered. If in doubt, the camshaft manufacturer will provide information on whether original or stronger valve springs are required.

Have any questions?

Our service team will be glad to help out: Mondays - Thursdays 08:00-17:00 CET, Fridays 08:00-16:00 CET, Phone: +49 / 931 250 61 16, eMail: service@wwag.com