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    I have about 80% or more of my current engine completed (Howell V2) and have encountered my old nemesis, vave sealing, as I have in all of the previous enginge I have built. I turn the seat and valve using the same setting on the compound and then lap the two with a fine diamond lapping compound. My result is that it takes many hours of tedious lapping, trial and test to get valves that seal. Surely there must be a better way. I would like to hear from others on how they handle this part of engine building.
    • CommentAuthorBruce Harr
    • CommentTimeSep 14th 2012
    Mr. Hatch...
    When making valves/seats as you describe, I always make sure that I have at least 1.5 -2 deg. difference between the seat angle and valve angle. try to keep the contact area very narrow. If you keep a very good finish on the seat and valve and maintain the concentricity on valve and seat/guide. lapping should not be needed. If you want to see the contact area you can use some very fine compound,install the valve,turn back and forth a few times. clean thoroughly (toilet tissue works great) Then you should observe a very narrow grey line all the way around the valve and also the seat. If these do not go all the way around both pieces you can see where the problem lies.
    • CommentAuthorgbritnell
    • CommentTimeSep 16th 2012
    Hi Mr. Hatch,
    This subject has been covered numerous times on other forums. It seems like this is one of the biggest problems builders have when making small engines. My method is as follows. First make the valves and seats 45 degrees. I'm not familiar with how Jerry Howell made the seats for his V-twin, in head or inserted valve chamber. In any case don't cut the seat when using either method. If the valve guide is not truly concentric with the valve port then no amount of lapping will clean it up. I make up a small seat cutting tool from drill rod, it has a stem to fit my required guide diameter (as tight as I can get it without binding) followed by a 45 degree cutting surface. Depending on the size I make no less than 3 flutes but up to 6 flutes for support. This tool is turned by hand just kissing the corner of the valve pocket to give a small seat area. Even if the guide and port aren't concentric this will align the two. By this method I rarely need to lap the valves for more than a couple of turns. Email me at and I will send you a drawing of the tool.