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Re: Valve lapping

From: joe d.
Remote Name:
Date: November 21, 2002
Time: 23:31:44


in many cases I have put new valves in with no lapping or any trouble. but... i also did a full emmision 305 monte once that cost me a teardown due to not checking the valves after the machine shop was done. So..just simply put the valve in its hole, then use a little valve compound on the seat area (first)and slowly work the valve back and forth until you hear the compound stop the scuffing noise, then pull the valve back out and be sure to see if there is a nice full ring all the way around the valve and seat. this ensures there is a good valve seat, and also that the valve did not get bent during shipping or in transit from machine shop to home. they make a suction cup for the valve to spin it back and forth, but i simply put the valve in the hole after applying the compound, then CAREFULLY and light pressure attach visegrips to the tip and use it to spin it back and forth while applying pressure to the valves head. remove all compound when done, and install valve seals after not before, the compounding method creates a lot of grit in the heads and will kill an engine if left in. hope this helps. I have seen machine shope also use the blue spray dye, and then spin the valve in the hole to check for seating. if they seat nicely, nothing needs done except reassembly. it will run fine and valves will seat perfectly. if the machine shop gives you the heads already done, then flip them over and spray penetrant in each chamber and see if it leaks into either valve area. that is when you would definitely pull apart and check by lapping.


Last changed: July 19, 2018