Valve Guides

Is oil getting past the valves, or does the cylinder head need to be prepared for higher revs? Valve guides guide the valve stem precisely and transfer heat from the valve to the cylinder head. We have guides for the intake and exhaust side for you who are rebuilding or tuning your engine.

What valve guides do in the cylinder head

The valve guide is pressed into the cylinder head and keeps the valve centred so it can seal tightly against the valve seat. At the same time, the guide dissipates some of the heat from the valve stem, which typically matters most on the exhaust side. If the guides are worn, the valve can develop play, seat unevenly and wear the seat and seals. This can lead to increased oil consumption and poorer compression. That is why guides are often replaced together with valve stem seals and possibly new valves.

How to choose valve guides

The guide must match both the engine and the valve. Pay particular attention to:

• Stem diameter: e.g. 5.5, 6.0, 6.6 or 7.0 mm – the size must match the valves you use.
• Intake or exhaust: many products are designed for one side, e.g. Brian Crower Honda H22A 5.5mm Intake or Mitsubishi 6G72 6.6mm Exhaust.
• Engine code: the range includes, for example, guides for Toyota 4AGE, Nissan RB26DETT, Nissan SR20DE(T) and Acura/Honda K20.
• Quantity per set: sets are available with e.g. 8 or 12 pieces, so check how many valves need replacing.
• Matching parts: some product names specify a part the guide must be used with, such as Ferrea's K20 guides.

Installation typically requires pressing out the old guides, pressing in the new ones and then reaming them to the correct clearance – depending on the product. The work is therefore often carried out by an engine machine shop, which can also inspect the valve seats and valve springs. In addition to Brian Crower and Ferrea, the category also includes GSC Power Division, Supertech and S&S Cycle.

Frequently asked questions

How can I tell if the valve guides are worn?

Typical signs can be blue smoke at start-up or under engine braking, increased oil consumption and measurable play between the valve stem and guide. The most reliable method is to measure the guides and stems with the cylinder head removed.

Should valve guides always be replaced together with the valves?

Not always, but the guide and valve work as a pair. If you switch to valves with a different stem diameter, the guides must match. With worn guides, it is often sensible to also replace the valve stem seals and inspect the seats.

Can I install valve guides myself?

It typically requires tools to press the guides out and in, plus machining to the correct clearance, and some cylinder heads also need to be heated. Without that equipment, an engine machine shop is often the safest choice.