If you're building, modifying, or maintaining a Honda B-Series engine, knowing the correct bolt sizes is crucial. Whether you're working on a B16, B18, or B20, having the right hardware can save you time and prevent costly mistakes.

At PLM, we know the importance of precision when it comes to performance, so we’ve compiled this comprehensive bolt size reference for your B-Series engine.

Honda B-Series Engine Bolt Size Reference

Below is a detailed guide to the bolt sizes for key components of the Honda B-Series engine. This will help you ensure you have the correct fasteners when assembling or upgrading your engine.

Cylinder Head & Valve Cover

Valve Cover Nuts: M6 x 1.0mm, 12mm hex
Valve Cover Studs: M6 x 1.0mm, 28mm length
Cylinder Head Bolts: M12 x 1.25mm, 150mm length (OEM)
VTEC Solenoid Bolts: M6 x 1.0mm, 25mm length
Distributor Bolts: M8 x 1.25mm, 30mm length

Intake Manifold & Throttle Body

Intake Manifold Bolts: M8 x 1.25mm, 35mm length
Intake Manifold Studs: M8 x 1.25mm, 45mm length
Throttle Body Bolts: M8 x 1.25mm, 30mm length
Fuel Rail Bolts: M8 x 1.25mm, 30mm length

Exhaust Manifold & Downpipe

Exhaust Manifold Studs: M8 x 1.25mm, 40mm length
Exhaust Manifold Nuts: M8 x 1.25mm, 12mm hex
Downpipe Bolts: M10 x 1.25mm, 35mm length

Transmission & Clutch

Transmission Bell Housing Bolts: M12 x 1.25mm, 40mm length (varies by location)
Flywheel Bolts: M8 x 1.25mm, 16mm length
Pressure Plate Bolts: M8 x 1.25mm, 20mm length
Starter Bolts: M10 x 1.25mm, 40mm length

Oil System & Engine Mounts

Oil Pan Bolts: M6 x 1.0mm, 25mm length
Oil Pump Bolts: M6 x 1.0mm, 30mm length
Oil Filter Housing Bolts: M8 x 1.25mm, 30mm length
Engine Mount Bolts: M10 x 1.25mm, 40mm length

Camshaft & Timing Components

Cam Gear Bolts: M10 x 1.25mm, 30mm length
Timing Belt Tensioner Bolts: M8 x 1.25mm, 35mm length
Crank Pulley Bolt: M14 x 1.5mm, 70mm length

Suspension & Subframe Components

Front Lower Control Arm Bolts: M14 x 1.5mm, 50mm length
Rear Lower Control Arm Bolts: M12 x 1.25mm, 40mm length
Subframe Bolts: M12 x 1.25mm, 45mm length

Having the correct bolt sizes when working on your B-Series engine ensures reliability and ease of installation. Whether you're assembling a high-performance build or performing routine maintenance, use this guide to keep your project on track. At PLM, we provide high-quality performance parts designed for enthusiasts who demand precision.

For all your Honda B-Series performance parts, including headers, exhaust systems, and intake components, check out our PLM store and get the best value for your build!

Got a B-Series project in progress? Share your build with us on social media and tag us! We’d love to see your setup and feature it in our community!