We use cookies for analytics, advertising and to improve our site. To find out more see our privacy policy.
Valve Train

Valve Train

Valve control

Camshafts, pushrods and tappets ensure that the 4-stroke OHV engine breathes quickly without choking. The pushrods are omitted on the SV engine, otherthan that it´s the same. The valve timing is an ingenious piece of engineering and - let's be honest - who could the fascination of the open ticking valve train of an F or J model from the 1920s ...


We have camshafts from The Cyclery, Samwel and Andrews for the IOE and SV engines to control the valve train, and Cannonball, Leineweber, Andrews and S&S for the OHV models. Valve trains such as tappets, tappet guides and pushrods come from Cannonball, Jims, S&S and Andrews. A wide range of quality parts for engines from Pocketvalve to Twin Cam.

How much play does the camshaft need?

The camshaft runs in bearings, up to and including Evolution in plain bearings or needle bearings. It must not have any perceptible play in these bearings. However, to prevent the camshaft from jamming when the timing cover is fitted, it must have a certain amount of play in the axial direction, i.e. lateral play, on all engines up to the Evo. Take the seal into account when testing and measuring! Approximately 0.1 mm is sufficient, even if H-D allows up to 0.125 mm.

Can the timing chain tensioner of the Twin Cam be adjusted?

No, timing chain tensioners on the Twin Cam work automatically. Either with spring pressure (Twin Cam 88) or with oil pressure (Twin Cam 96, 103 and 110). This means that the timing chains on the Twin Cam always have the correct tension.

What is timing and how do I compare it?

Timing is the name given to the opening and closing times of the valves. In modern engines, an intake valve opens shortly before top dead center of the piston and closes after bottom dead center. An exhaust valve opens before reaching bottom dead center and closes after reaching top dead center. Inlet and outlet valves are open simultaneously for a short time. This time span is called overlap. As a rule of thumb, the greater the overlap compared to other camshafts for the respective engine type and the later the intake valve closes after bottom dead center, the more suitable a camshaft is for higher compression and higher revving engines.

Why can't I set valve clearance on the Evo?

Original Evolution engines have automatic valve lash adjustment, just like Shovelhead and Panhead. Unless they have been removed by the previous owner, all these engines have hydraulic units that eliminate valve lash as soon as oil pressure is applied. With the Evolution, there is also no longer a basic setting like on Panhead or Shovelhead engines. The pushrods have a fixed length, the preload of the hydraulic units is determined when the pushrods are installed.

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