A common question is what is a three-angle valve job. In an attempt to explain, I'm including some sketches out of our Performance Handbook. A picture is always worth a 1000 words.
First a sketch of a "stock" rebuild so you can see what Ford intended.
Now a sketch of the three-angle cut. Some people make a four angle cut by adding a 60 degree cut down into the port bowl.
The cuts are not made to the valve, but rather to the valve seat.
A "backcut" can be made to the valve that will trick the engine into thinking that it has a higher lift camshaft. On a stock valve there is a pronounced lip where the second cut is made on this modified valve.
We don't recommend doing a backcut to an exhaust valve except on a "race-only" engine. The exhaust valve absorbs a lot of heat and needs its mass on a street engine.
Please start a new topic to ask questions.
Good Luck
First a sketch of a "stock" rebuild so you can see what Ford intended.
Now a sketch of the three-angle cut. Some people make a four angle cut by adding a 60 degree cut down into the port bowl.
The cuts are not made to the valve, but rather to the valve seat.
A "backcut" can be made to the valve that will trick the engine into thinking that it has a higher lift camshaft. On a stock valve there is a pronounced lip where the second cut is made on this modified valve.
We don't recommend doing a backcut to an exhaust valve except on a "race-only" engine. The exhaust valve absorbs a lot of heat and needs its mass on a street engine.
Please start a new topic to ask questions.
Good Luck
