Lapping

[Jethro]

Now, I know my dog makes this sound when drinking out of the toilet, but in respect to my Suzuki- what the heck does lapping the valves mean?

[SqDancerLynn1]

It is a process during a rebuild A small amount of grinding compound is put on the valve and the valve is rotated back and forth to get the best seal possible against the valve seat

[shaftzuki]

check out this link:

http://www.dansmc.com/valve.htm

8)

[Jethro]

Good article, thanks. 8)

[Anonymous]

Lapping the valves seems like religion. You'll never convince me that you need to do this if a proper valve job has been done. I have never heard of high end racers doing it. As a matter of fact, some of the articles I've read that were written by the likes of Keith Black specifically went out of their way to say they DON'T do it.

To each his own I guess. I look at it as 'shade tree'.

[Anonymous]

Lapping is not really worth the trouble. First the compond can get into the valve guide causing trouble. Second the process of lapping the valves flattens out the seats on both the valave and the valve seat. There is supposed to be a .5 to 1 degree difference between the two to enable the carbon build-up to be chipped away with the movement of the valve. The chipping action is also helped along with the sharpness of the edges on the ground edges. lapping rounds out these edges.
To be able to propely lap valves you still have to take the head completely apart. While the head is apart to the point that you can lap the valves, you might as well just pay some one with the correct tools to grind the valves and seats. If you are trying to save some money, you could take the head and the valves to the machist after you have disassembled and cleaned everything. Most machist will do a simple grind for less money than if they have to disassemble clean and then reassmble the head.
Now, that I am registered with this site I wuill try to help out on the techinical questions. If for some reason that someone wants my input and I have not responed then please e-mail me.
I have worked in the past as a ASE certified master machinist and master mechainic. I have worked on just about any type of motor and/or engine. I also have an extensive backround in the electronic industry.