What angle are valve seats cut at?

The actual valve-seat angle is generally 45 degrees.

When a valve face is ground at 44 degrees and valve seat is ground at 45 degrees the one degree difference in angles is called?

For instance, if the seat is ground 45°, the valve face is ground at 44°. This one-degree difference is called the interference angle, Fig. Interference grinding will raise the surface loading at the seat contact point due to the reduced seating surface area.

What is valve seat cutting?

A valve seat cutting machine is the most accurate and efficient tool for cutting valve seats. As the valve seat has different angles, hand cutters will struggle to achieve the precision needed to ensure each angle is accurately cut.

Why are three angles cut into the valve seat?

Because each turn is less sharp, more of the air can make the turn, causing flow to increase – particularly at low valve lifts. The use of three-angle seats in production engines is a compromise between airflow and the cost of manufacturing.

Why do you cut valve seats?

Yes, narrower seats have better airflow, but there’s a trade-off. Narrow seats are less durable so you’ll be working on them more often, which leads to another problem. The more you cut away at the 45° angle, the wider it will become and the lower your valve will seat which opens another whole can of worms.

How do you perform a 3 angle valve job?

The basics of a three angle valve job: On the inlet valve, the lap marks should be placed on the outer edge of the 45° valve face. This takes full advantage of the diameter of the valve. When the lap marks sit inside the outer edge of the valve, the overhanging portion of the valve serves as an obstruction to flow.

What happens when valve spring tension is too low?

If the spring pressures are too low, a condition called “Valve Float” will occur.

Which valve guides will last the longest?

Cast iron guides work fine and are easy to install, last a long time, and may be clearanced with a reamer. Bronze guides require more clearance, must be clearanced with a hard stone wet hone (Sunnen type), and need to be installed by someone with MG specific experience and the proper equipment.

What is a 3 angle valve job?

A 3 angle valve job is the process of machining the contact area of the underside of the valve, so that the mating surface is smaller or sharper, and making the seat angle greater. This allows the valve to seal faster and more tightly.

What is a valve seat in an engine?

In simple terms, the Valve Seat is the seat for the air intake valve and air exhaust valve. It is the part that makes contact with the valve, and maintains the airtightness of the combustion chamber.

How do you perform a 3-angle valve job?

What is triple cut seat?

Triple cut valves (AKA 3-angle valve seats) are where the valve seats are machined at 3 progressively steeper angles.