Intake Valves

Can the original intake valves handle the revs, boost pressure and camshaft your project is going to run? This category contains valves for the intake side of the cylinder head – in standard and oversize dimensions, as single valves or complete sets for engine builds and cylinder head work.

What the intake valve does in the cylinder head

The intake valve opens and closes the path of the air-fuel mixture into the cylinder. The camshaft opens it, and the valve spring keeps it closed. At higher revs, with more aggressive cams or more boost, material, weight and sealing can matter for whether the valve follows the cam and seals properly. The exhaust side works at completely different temperatures, so those valves are found under exhaust valves, while both types are grouped under engine valves.

How to choose intake valves

Start with the engine and the dimensions, not the brand. The product names typically state:

• Head diameter, e.g. 30, 32, 33.6 or 35 mm. A head larger than stock, e.g. +1 mm, may require machining of the valve seat and cylinder head.
• Stem diameter and length, e.g. 5.47 mm and 109.30 mm. These must match the valve guides, springs and installed height.
• Seat angle, e.g. 20 degrees, which must match the seats in the cylinder head.
• Quantity: single valve or set, e.g. with 8 valves.

We stock valves from brands including Brian Crower, with variants for e.g. Mitsubishi 4B11T, Toyota 2JZGTE and Honda K20A, and Ferrea as well as Supertech, GSC Power Division and Edelbrock. Always check the dimensions for the specific part number against your engine. Ideally, have an engine builder assess springs, guides and valve-to-piston clearance before the parts are installed.

Frequently asked questions

Should I replace intake and exhaust valves at the same time?

It depends on the project and the condition of the cylinder head. In a major rebuild, both sides are often replaced at the same time so seats and guides can be machined in one go. However, it can also make sense to replace only the intake valves.

Can I use oversize valves without machining the cylinder head?

Typically not. A valve with a larger head than stock normally requires the seat to be machined or replaced so the valve can seal properly. This is a job for an engine shop with the right equipment.

What else should I check when replacing intake valves?

Check that the valve guides have no play, and that springs and retainers match the new valve's stem and length. Also check the valve-to-piston clearance. The valves should normally be lapped into the seats during installation.