Since I have been intrested in tools I have saw plenty of old valve grinders, both locally and online. I feel a little stupid in saying I don't really get the whole valve grinding process and why one would do it. Could someone please explain valve grinding to me. I can't find any good sites to explain it but if you have one posting the link would help to.

Why is the easier part.

Poppet valves in gasoline engines can not leak, bad things happen when they do, If an exaust valve leaks when the cylinder fires, hot exhaust gas will cut a channel along the edge of the valve making the leak bigger and bigger until the valve loses part of it's side and the engine won't run at all. If the intake valves leak, hot gas ignites fuel in the carburator making the engine backfire all the time.

Engine blocks, and valves are not quite a perfect fit when made, so they are lapped, or ground into each other so they both have exactly the same shape and are both the same size at the hole, so they don't leak. Older engines, before hardened inserts, and particularly when carbon deposits were a problem, and carbon occasionally got stuck under the valve, also needed the valves and block relapped from time to time to adjust for normal wear.

If the valves were new, or in fairly good shape, all that was needed was to put some abrasive compound on the edge of the valve and spin it around in the hole in the block. For damaged or badly worn valves, there were tools to cut off some metal on the edge of the valve to make it smooth and round again, then it was also lapped in place....

Good, I'll only add a few things.    I went to school back when it wasn't un common to grind the valves on an automotive engine every couple of years.  Hard running would get the valves hot, the heat would slightly warp them so they wouldn't fit on the seat well.   Weak valve springs would also let a valve burn, as it would not close fast enough.   Imagine a Tupperware lid that doesn't close all the way at one spot.   The little oscillating grinders we see so often, suction cup grinders, are actually just valve lappers.   These just moved the valve like Rusty pointed out.  In the repair shops and engine rebuild shops there were larger machines that actually machined a new surface on the valve, until the valve was beyond specification.   There were also valve seat grinders, that came with many round stones and mandrels that would grind a new surface on the seat, which was in the head or the block, depending upon it being a flat head or an overhead valve engine.   For the poor man there were the hand cranked ( grinders), where one just put on the lapping compound and cranked away until the burnt area was gone.  Either way the finish  was done with the lapping compound for a final fit.   The auto dealership I work in, gave away our valve grinding equipment when I wasn't looking.  With the engines today, the gas, the oil, and fuel injection it is almost a thing of the past.

Back in the day, I ground and lapped thousands of valves on motorcycles. A valve grinding set up and several stones and grinding heads. For lapping, I used a piece of clear fuel hose that I pushed on to the valve stem, after putting lapping compound on the valve face, then I would spin the valve back and forth by hand. The rubber suction cups never worked for me.

I recently rebuilt a Kohler engine and  was short and intake valve.So I went over to a friends machine shop and put the old valve in his valve grinding machine and trued it up.I brought a friend son with me who just finished high school small engine class. The kid never saw a valve grinder or a lapping tool. They never mentioned this in his class.I guess it's too old school.

There was a period when they made valve seat cutters with guides that you operated by hand.
Most came in nice wooden boxes with a Varity of different sizes and angles.
Once the unleaded gas and hardened valve seats and valves were fazed in , valve repair
was a thing of the past.
Restorers of tractors , vintage engines and cars still like to do their own valve work with the old tools.

I've been looking for a reasonably priced seat cutter set  for some time now.I'm not having much luck. About $600.00 new and $350.00 and up for used ones. Some day I'll have my own.

Thanks for the explanation guys, that really helped.

Quote from: Nolatoolguy on September 04, 2013, 07:51:05 AM
Thanks for the explanation guys, that really helped.

It helped me also.  Thanks for the thread.

Quote from: Papaw on September 01, 2013, 07:20:57 PM
For lapping, I used a piece of clear fuel hose that I pushed on to the valve stem, after putting lapping compound on the valve face, then I would spin the valve back and forth by hand.

I was (and still am) too lazy for that. I stick the valve through the head and chuck it up into a drill motor. Put a little compound on it and stand on the head and pull up on the drill motor. Oh yeah, power lapping, baby!!!

Back in the day when  you pulled the head every 30k miles to decarbonize  the head, lapping was all that was needed. Engines with 100-200k have a little more wear.  Here is a pic of my K.O.Lee, the seat grinder is a dry Black and Decker(no pic it is in cabinet)  A operator's manual here http://www.liberatedmanuals.com/TM-9-4910-428-10.pdf they were also sold under Snap-on brand.

I have a weakness for tools in old wooden boxes.

here is a Willis -Jones valve reseater.

http://www.flickr.com/photos/skipskip/sets/72157635423756558/



SEP 102 by skipskip, on Flickr


SEP 099 by skipskip, on Flickr



It's a complicated old toy, but it prolly did the job.

Bet the garage owner paid a lot of pre-depression dollars for it.

Quote from: skipskip on September 09, 2013, 08:36:37 PM
I have a weakness for tools in old wooden boxes.

here is a Willis -Jones valve reseater.
......

Complete with instructions.  Very nice!

And, to add to the conversation, the whole business could get pretty sophisticated.  Later valves would get as many as three different angles ground on the valve where it was going to contact the seat.

yes 3 different angles where the vale meets the seat, then custom grinds / blends on the back side of valve , from the seat edge to the stem.