valve face runout

O

ole4

Member
Was wondering if anyone is checking new valves for runout? I was having issues where even though seat concentricity was good when I would drop in a valve with stem and guide dry it would not bounce on the seat like usual. rechecked the seat, lapped and still no bounce. Now for many years of doing this on automotive and motorcycle valves when seat is concentric and valve is good it will usually bounce off the seat unless the guide is too tight and the valve falls in slow. I bit the bullet and bought a valve face runout gauge that reads in ten thousandths. What I found was the stock Chinese valves from the take out harbor freight motors were all under .001 from .0005 to almost .001. The aftermarket valves were all over some over .003 runout others almost 0. I had two identical valves one with .0007 runout and another with .0032. These were 32mm valves and when I did the bounce test the .0032 did not bounce. When I do a vacuum test I do not do it from the port but pull vacuum from the chamber using a thick acrylic plate with a rubber gasket open around the chamber so I can add alcohol to see leaks, I use stock springs and even though the .0032 valve seals it does leak a small bit in one spot on the valve. I was just wondering if anyone else has seen this with aftermarket valves?
 
I also would be suspect of the valve grinding machine that does the refacing. Back when I picked up a nice used Sioux machine I was all excited about gaining another tool to the shop until I soon found out that it wouldn't chuck up and spin anything true. I spent many hours trying to rebuild the chuck with out any luck. Now it is just a nice bench grinder.
 
I do not have acess to one. I can do them on my lathe with a tool post grinder and a collet but runout measured on the valve stem right at the collet is almost .002. Works good for regrinding a valve for a mower but not good enough for a competition head.
 
I have the same trouble with my three jaw chuck and lathe. I guess when I need to get 0 run out it is time to mount up the four jaw chuck and chase the needle.
 
I did a lot of reading on speed talk forum about getting a valve grinder and lots of issues with getting low runout with them as well as issues with smaller stems.. They have to change motor bearings, spindle bearings and the balls in the chuck. The balls not kept clean are much harder than the chuck so it wears the chuck from the grinding dust of the wheel over time. Replacing just the balls does not fix the issue as the chuck itself can wear. Valves are only 15-17 bucks, I will just order some more and just check them before using. Looking online for a spec for runout I see values of 0011 to 002 in various posts. I am going to shoot for .001 or less.
 
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