Pushrod Length Calculator

We’ve created this pushrod length calculator for engine builders and automotive enthusiasts to help measure the optimal size of pushrods.

Pushrods transmit motion from the camshaft to the rocker arms, actuating the valves. The correct pushrod length ensures proper valve timing and lift, contributing to engine efficiency and performance.

When upgrading a V8 engine with new cylinder heads and a high-lift camshaft, a pushrod length calculator would help determine the ideal pushrod length to accommodate these changes, ensuring optimal valve train geometry.

Pushrod Length Calculator

Engine Type	Block Deck Height	Cylinder Head Height	Rocker Arm Ratio	Valve Lift	Lifter Diameter	Calculated Pushrod Length
Small Block Chevy	9.025″	1.200″	1.5:1	0.480″	0.842″	10.103″
Big Block Chevy	9.800″	1.300″	1.7:1	0.520″	0.875″	11.109″
Ford 302	8.200″	1.250″	1.6:1	0.480″	0.875″	9.343″
Ford 351W	9.500″	1.300″	1.6:1	0.500″	0.875″	10.725″
Chrysler 360	9.600″	1.350″	1.5:1	0.500″	0.904″	10.796″
LS Engine	9.240″	1.100″	1.8:1	0.600″	0.842″	10.158″
Ford Coyote (5.0L)	9.500″	1.200″	1.6:1	0.500″	0.875″	10.325″
Dodge HEMI (5.7L)	9.600″	1.300″	1.5:1	0.490″	0.904″	10.566″
Pontiac V8 (400)	10.200″	1.350″	1.5:1	0.480″	0.842″	11.180
Buick V8 (455)	10.500″	1.400″	1.6:1	0.510″	0.875″	11.294
Chevrolet Big Block	9.800	1.400	2:1	0.600	0.875	12.000
Nissan RB26DETT	9.000	1.200	2:2	0.550	0.865	10.300
Subaru EJ20/EJ25	8.000	1.150	1:5	0.450	0.900	8.225
BMW M50/M52	8.700	1,250	2:5	0,480	0,850	9,450

Pushrod Length Formula

The formula is expressed as:

Pushrod Length = Block Deck Height + Cylinder Head Height + (Rocker Arm Ratio × Valve Lift) - Lifter Diameter

The pushrod length formula considers several key factors:

• Block deck height
• Cylinder head height
• Rocker arm ratio
• Valve lift
• Lifter diameter

Let’s use the following measurements (in inches):

• Block Deck Height = 9.000
• Cylinder Head Height = 1.200
• Rocker Arm Ratio = 1.6:1
• Valve Lift = 0.500
• Lifter Diameter = 0.842

Pushrod Length = 9.000 + 1.200 + (1.6 × 0.500) - 0.842
= 9.000 + 1.200 + 0.800 - 0.842
= 10.158 inches

How to Measure Pushrod Length?

Measure block deck height: Distance from crankshaft centerline to top of block deck.

Measure cylinder head height: Distance from head gasket surface to rocker arm mounting point.

Note rocker arm ratio: Typically stamped on the rocker arm or provided by the manufacturer.

Determine valve lift: Maximum lift of the valve, specified by the camshaft profile.

Measure lifter diameter: Diameter of the lifter body.

Calculate: Apply these measurements to the formula.

Fine-tune: Make small adjustments based on actual fitment and valve train dynamics.

While rebuilding a small-block Chevy engine, you measure:

• Block deck height: 9.025″
• Cylinder head height: 1.300″
• Rocker arm ratio: 1.5:1
• Valve lift: 0.480″
• Lifter diameter: 0.842″

Calculated pushrod length:
9.025 + 1.300 + (1.5 × 0.480) – 0.842 = 10.203 inches

How do I know if my pushrod length is wrong?

Incorrect pushrod length can lead to various issues:

• Valve float: Too short pushrods can cause valves to remain open longer than intended.
• Reduced lift: Overly long pushrods may not allow full valve lift.
• Premature wear: Improper geometry can accelerate wear on rocker arms and valve stems.
• Noise: Incorrect length often results in increased valve train noise.

If your calculated pushrod length is 10.203″, but you use 10.000″ pushrods, you might notice increased valve train noise and premature rocker arm wear due to improper geometry.

How long is a 351 pushrod?

For a Ford 351 engine, the pushrod length varies depending on the specific variant (Windsor, Cleveland, or Modified):

• Block deck height: 9.500″
• Cylinder head height: 1.300″
• Rocker arm ratio: 1.6:1
• Valve lift: 0.500″
• Lifter diameter: 0.875″

Pushrod Length = 9.500 + 1.300 + (1.6 × 0.500) – 0.875 = 10.725 inches

This calculated length is close to the typical range for a 351W, which often uses pushrods between 7.950″ and 8.620″ depending on specific components.

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