Stock Harley-Davidson Valve Tip Protrusion with Stock Valve Sizes

Application Tip Protrusion
900 & 1000CC Iron Head XL Sportster 1957 – 1983 Tip to Valve Guide Flange: 1.375″ (max. limit 1.420″)
 1200CC Pan Head & Shovel Head 1948 – 1979 Tip to Valve Guide Flange: 1.500″ – 1.550″
 1340CC Shovel Head 1979 – 1984 Tip to Spring Seat: 1.600″ – 1.650″
Evolution Big Twin 1984 – 1999 Tip to Spring Seat: 2.000″ – 2.050″
Evolution Sportster with 5/16″ Stems 1986 – 2004 Tip to Spring Seat: 2.000″ – 2.050″
Twin Cam with 5/16″ Stems 1999 – 2004 Tip to Spring Seat: 2.000″ – 2.050″
Twin Cam with 7mm Stems 2005 and up Tip to Spring Seat: 2.025″ – 2.069″
Sportster with 7mm Stems 2004 and up Tip to Spring Seat: 2.050″ – 2.082″
V-Rod Tip to Spring Seat Intake: 1.739″ – 1.762″, Exhaust: 1.704″ – 1.728″

 

Tip length on the Sportster 7mm Valves is .100″ vs. .070″ on the Twin Cam 7mm Valves, but the spring spacing is the same because the protrusion is higher on the Sportster. All specifications apply to stock cylinder heads.

On heads with over-sized valves and modified camshafts, you may need to sink the valve seat deeper for valve to valve clearance and this may result in higher protrusion. The engine builder needs to decide what minimum spacing is needed between the intake and exhaust valves and then sink the seats to get the correct valve to valve clearance at TDC lift.

Stock Head Thickness: Evolution Big Twin: 3.750″; Twin Cam Big Twin: 3.750″; Evo Sportster: 3.700″

Heads with over-sized valves, modified camshafts with longer overlap, or heads that have been milled fro increased compression require special attention to valve to valve piston clearance. Piston’s valve pockets need to large and deep enough to prevent collision with the valve. Also adjustable push  rods might be required if the heads have been milled of if the valve tip protrusion is higher than the stock specifications. All valve spring spacing must be adjusted to get the correct spring pressure.

Source: www.av-v.com

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