Wednesday, September 04, 2013

Lapping valve seats

I was hanging out with Joe Groeger this past Sunday. I joined him for breakfast at his usual spot and we had some coffee and oatmeal together. It's wonderful how many people will stop and say hello to Joe and his dog Lola while he is eating breakfast.

Afterwards, we returned to the shop and he said, "Let's work on one of your projects. What have you got?"  I went out to my car and pulled out a pair of R69S heads that are going on my own bike as part of my long-running R69S motor rebuild.

I brought the heads back into the shop and put them down on the table by the door.  It was then that Joe noticed that the lighting for this table isn't too good.  When you are 94, I suppose you need good lighting. So Joe set about trying to rig up some lighting for his table. When you are Joe Groeger, you can't just string an extension cord across the floor and setup a table lamp. You have to do it "right" ... hang some 2x4's from the ceiling joists, reinforce them with a triangulate, tap into the correct lighting circuit, run new electrical flex conduit from a junction box down the 2x4s, and then install a grounded 4-plug outlet box about 3' off the table.  This is why Joe's shop is so amazing.  Even when he is building something for himself, he builds everything  so that it will perform flawlessly for another 100 years.  And Joe is 94 years old.

So yes, Joe does have a way of getting side tracked on shop projects while he working on other projects. These side projects are often fantastic and wonderful in nature, so I don't usually complain when we get off-track. I just go with the flow and I usually learn something fantastic and wonderful from watching and helping. Last week Joe decided that the knob which tightens the collett on one of his lathes was too small and too hard to grip.

So we rooted around in his parts bin until we found a lovely wooden wheel that looked as if it had been made in 1925 and we transformed it into a lathe handle.  Talk about wonderful. I was in heaven.

But today I was a little under the gun. I've decided to get my motor swap done in time for the Norcal TT which is in 2 weeks.  I had to get these heads done today.  So with Joe preoccupied which his electrical project, I went in search of his box of tools for head reconditioning.  Joe keeps all of his tools in bins in a room dedicated to /2 engine work.  Each bin holds a selection of tools, jigs and parts for performing a particular job on a vintage BMW motorcycle. In this sancta sanctorum, the air is still and quiet and the aroma of bare metal and decade-old oils calms the mind.

On the top shelf I found an unlabeled box which contained some devices I recognized to be valve seat grinders. I also found some valve stem guide reamers and drifts, so I knew I had the correct box. I took the box out to the main workshop and emptied the contents on the bench.

I have always removed valve springs using one of those c-clamp looking things that reaches around the head and squeezes the valve from both sides. They are clumsy and awkward and always managed to slip off the face of the valve and send springs and keepers flying everywhere.  I did not find a valve spring compressor in the box so I asked Joe where I could find one and he walked over and showed me his system.

His valve spring compressor consists of a stand that he made which holds the head by the valve face.  Two "arms" hold the head and keep it from slipping off the stand.  Joe had made several windows bushings for various BMW models (R50, R60, etc.) and they were in the box.  You can see them in the photo above. The ends of the window bushings were stepped on a lathe so that they gripped the valve spring tops and would not slide off.  Once assembled, the entire unit was placed in the arbor press and the keepers were easily removed.  It was a simple (and fast) two-handed operation...and brilliant!

I was so excited that I forgot to take a photo of removing the keepers.  Here is a photo showing the head stand with the valve lapping tool installed.  (I'll get to that later.)

Next up was grinding the valves. Joe has a cool, old valve grinder that does a great job.

The valve guides on these heads are well within spec so I left them in place and just ran the reamer through with a hand tool to remove any carbon build up.  I then taped up the guides and media blasted the heads, valves, valve covers and finned exhaust rings.

When it comes to lapping valves, I've always used one of those suction cups on a handle things that you spin between your hand. But I couldn't find it in the tool box.   "They don't work!" says Joe.  Joe's valve lapper is another one of those items in his shop that looks as if it was created as a side project during a main project, and built to last 100 years.

An old Jacobs chuck mounted to a shaft with a hand grip. After lubing the valve stem with oil and coating the valve seat with grinding compound, the chuck is tightened on the valve stem.  

Then, the entire assembly can be lifted up by the handle on the chuck and the head can be "swung" around in circles, effectively (and quickly) lapping the valve seats using the weight of the head. It is quick and easy and, again....genius. 

I had some video of me swinging the head around and lapping the valves, but my digital camera ate the footage. Next time I do it I'll try again to shoot video.

Putting the heads back together was a snap. 

My heads are now ready to go.

The only thing I am waiting on right now is a pair of Ed Korn's lightened wrist pins.  Once they arrive, I will be able to finish up the motor and break in the new motor before the big ride!

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