Author Topic: Grinding Valves with a B&D Refacer -  (Read 8933 times)

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Offline goodfellow

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Grinding Valves with a B&D Refacer -
« on: May 25, 2010, 02:44:32 PM »
While waiting for my cylinder head and block to get machined, I'm using the time to clean up parts and to address the valves. The valves will get ground on my "new" B&D valve refacer.



First up is the #1 exhaust valve. The grind on all valves is a standard 45 degrees. Since exhaust valves and seats take more of a beating, I decided to address these first. The body and stem measured within spec, so no valve guide wear was detectable, but as you can see in this pic, the face of the valve was very pitted.



Setting up the valve grinder is pretty simple. Chuck the valve, bring it very close to the grinding wheel (without actually touching) and start the chuck motor only. Then bring the grinding wheel forward to where it just makes the slightest bit of contact with the valve -- you can hear a very faint grinding sound. At that point, the micrometer wheel on the grinding head is "zeroed", and the main grinding wheel and coolant is started.







The valve is now cut according to the "zeroed" dial -- I start with a 0.001" first cut by dialing in 0.001" and moving the valve across the face of the cutting stone.





The face of the valve will start to clean up and become shiny -- Then I continue to feed 0.001" at a time until I've cut 0.003"- 0.004" off the face --
In this case you can see that my exhaust valve is still showing some pitting and even by adding another 0.001" (making a total of 0.005" grind) the face of the valve is still not completely smooth and concentric

Conventional thinking suggests that if the valve doesn't clean up after a 0.005" grind, then it's best to trash it because it will eventually sit too deep in the valve seat; hence the valve seat would have to be modified with an offset grind to accommodate the difference. That's way too much work for this XK head -- better to replace the valve (they cost less than $10 each). All my exhaust valves are pitted and so I will replace them.



Better news on the intake valves. As with the exhaust, the #1 intake valve was ground after the dial was "zeroed" and it only took 0.002" to get a clean concentric face



Since 0.002" was ground off the face (making the valve sit deeper in its seat) the stem will have to be ground the same distance in order to compensate for the increased height on the tappet. To do that, we need to grind the stem on the right wheel (flatwheel).

Again, the valve is chucked into the stem grinding fixture and brought close to the flatwheel. The wheel is turned on and the micrometer feed is used to allow the stem to just make the slightest contact with the wheel (a slight grinding noise is what I'm looking for at this point). The wheel is turned off at this point and just as in the previous grind, the micrometer dial is "zeroed" and the cutting fluid and wheel are turned on again.







The valve is ground 0.001" at a time by moving the fixture across the grinding wheel until a max of 0.002" is indicated. At that point the valve is symmetrical again.



All of the intake valves can be successfully refaced -- Voila!! A perfectly ground intake valve



 




 
« Last Edit: March 13, 2011, 10:09:38 PM by goodfellow »

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Grinding Valves with a B&D Refacer -
« on: May 25, 2010, 02:44:32 PM »