Has anyone ever overlapped there valves on a 00' Ford Focus ZX3 with the Zetec engine?

Question

My engine is stock and is the 2.0 liter dual overhead cam Zetec engine. I want to overlap my valves, has anyone ever done this? What are some tips?

Answer 1

What are you talking about, overlap your valves?

Answer 2

I'm not sure what your talking about.

Lapping valves refers to an old technique of restoring the valve seating surfaces using lapping compound and spinning the valve by hand or with a hand-operated drill and pressing it gently against the valve seat. It's worthless with today's modern hardened valve seating surfaces and hardened valve seats.

Overlap refers to the period in the four-stroke otto cycle where both the intake and exhaust valves are partially open. A certain amount of overlap can increase performance by both allowing more complete scavenging of the spent combustion gasses and allowing a more complete charge of fresh fuel-air mixture for the next power stroke. You change the valve overlap by installing a new camshaft with greater than stock overlap; it's not an adjustment that you can make.

Answer 3

You can't overlap valves. If you have a bad valve, you need to buy a new seat and a new valve...rather inexpensive. They will be ground to 47.5 degrees and 43.5 degrees or whatever it is....can't remember...getting old. Weld a small bead to the old seat....don't damage the aluminum head....then use the bead to pry on to pop the old seat out. After sitting in the freezer for a few hours....take the new seat out and put it into the head. Don't dilly dally or you'll have to re-cool it. Tap it firmly into place with a brass drift. Then lap the valve in. Clean thoroughly with brakeclean and put the valve back in with the spring and locks. Now, you can reassemble in reverse order and your valve problem will be fixed.