Valve refacing: grinding vs. machining

[supersteve]

I was always under the impression that valve refacing was a grinding operation until I saw this Neway promo video:

At about 19:15 they show a valve being faced on a lathe.
I'm tempted to try this on my top quality HF 7X10 with some old junk valves.


Anyone have any experience with this?

 

[mbshop]

After grinding like forever, I started using the neway system in the late 80s. Never looked back.

 

[MShaw]

You just need to be sure your lathe chuck is holding them true. After use most 3 jaw chucks will develop some runout. Check with an indicator on the valve stem. It may be necessary to hold them in a 4 jaw chuck and indicate them.

 

[Showkey]

The old school valve grinders also used a three jaw chuck.
Many valves have inserts so grinding or cutting is not recommended. Often valves are so cheap replacing is not a huge concern. Then there is the lack of valve margin that makes cutting or refacing less viable.

I used Neway from the '80s on as well........great product.

Example of the old school grinder:

 

[Firebrick43]

I would suggest an er40 chuck and collets to hold the valves.

You might run into issues with the little harbor fright lathe. Carbide tooling put greater pressure and the hardness of the valve increases it even more. Size is deceptive, but the HF (and hobby lathes in general) lack ridgidity this leads to chatter. Sharp hs tooling is prefered as it reduces pressure and therefore chatter. I doubt he tooling will work on valves though.

If you do use carbide insert choose one with a positive cutting angle and narrow radius. Most cheap inserts are negative cutting angles and are used on 5-10hp+ Machines that weigh several thousand pounds.

 

[Packard V8]

FWIW, I've always ground valves on Sioux or Kwik-Way machines. Recently, I was reducing the diameter of GM LS intake valves for use in Studebaker V8s. Having sixty-four of them to do, I asked a friend with a CNC lathe to do them. I'd expected to have to grind the final finish, but it took him only seconds per valve and the finish and runout was perfect.

jack vines

 

[kkroger]

Needs an Air Collet Closer and a stem Stop but I can certainly grind them faster than that. Seats are another deal entirely, I can grind them but I would prefer to use the seat cutters.

 

[supersteve]

Well, I gave it a whirl with an intake valve from an old American V8 and the results were about what I expected. It gave a true cut but the finish was unacceptable. I suppose if I was desperate i could have used a block and some 180 grit sandpaper to finish. You could tell the old girl was at her limit: lots of flex, feed, feed, complain and then cut some chips. I used HSS as Firebrick suggested, ground pretty sharp with some positive rake, this has always given me the best results in the past. Didn't have an exhaust to try and I'm a-scared to....

I may get a Dremel and try to rig it as a tool post grinder. Maybe rough cut with the HSS and then grind to finish. I don't have the money or space for real equipment like Jack's friend.

Questions for head guys-
-Do you have a rule of thumb for valve margin before you toss?
-Do you ever cut that lip off an intake valve for a performance job?


Also, Hello MShaw, how's everything going In York?
The last time I saw that place was in the rear view mirror exactly 20 years ago.

 

[supersteve]

Also, one more question please. Does anyone know of a good source online for Neway seat cutter kits?