1. Rocker Arm
Pushrod Length
Lifter Plunger Preload
Lifter

3. Aftermarket rocker arms with different geometry can have an effect on the needed pushrod length
Anything that causes stem protrusion to change can have an effect on the needed pushrod length.
Valve Spring Surface
(part of cylinder head)
Anything that changes the overall height of the cylinder head can have an effect on the needed pushrod length
Changes in head gasket thickness can have an effect on the needed pushrod length
Anything that changes the overall height of the cylinder can have an effect on the needed pushrod length
Changes in base gasket thickness can have an effect on the needed pushrod length
A different type of lifter can have an effect on the needed pushrod length
Cams with a different base circle can have an effect on needed pushrod length

4. Top Dead Center on Overlap
Intake
Exhaust
Intake Valve
Starting to Open
Exhaust Valve
Almost Closed
Measure from case deck
down to top of lifter
Measure from case deck
down to top of lifter

5. Top Dead Center on Compression
Intake
Exhaust
Both Valves Closed
Measure from case deck
down to top of lifter
Measure from case deck
down to top of lifter

6. .100” ideal preload
.200” available travel
Lifter plunger

7. TDC Overlap
TDC Compression
TDC Overlap
Intake Stroke
Compression Stroke
Power Stroke
Exhaust Stroke
BDC
BDC
Intake Valve Open Shown in Red
Exhaust Valve Open Shown in Blue