Re: [MV] Valves: to lap or not to lap
Tue, 26 Oct 1999 21:19:55 -0400 (EDT)


There is no need to lap your valves if you had a valve job done. Lapping valves instead of a valve job is kind of like a band aid fix. The engine will run OK for a while, but the valves will start to leak resulting in power loss. Most automotive machine shops can handle a valve job on a flat head without any problem. I lapped vavles for years before I bought a valve grinder and a seat grinder and I can assure you there is no comparison. If you do lap, lap the absolute minimum it takes to produce a 360 degree contact with the seat. Do not mix the valves up. You can test by assembling the valves into the block and turn the engine upside down. Pour kerosene into the ports. There should be no outright leaks. Good luck.

Dave Fillman
45 MB

---- you wrote:
> All,
> I am reassembling my M38A1 engine. The machinist recommended to "lap
> the valves in good". Now my question is when do I know when I'm done
> lapping? I'm using a hand lapped and Napa grease based silicon grit
> compound. How long can I expect this to take? Any advice is welcome.
> Dave

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