To Lap or not to Lap?

HingsingM37 · Post by **HingsingM37** » Wed Aug 27, 2008 6:16 am

Ok, I always thought that after a valve grind whether it be tri-angle or single the valves should be lapped in with Clover compound to ensure a good face to seat mating? Opinions?

Lifer · Post by **Lifer** » Wed Aug 27, 2008 9:01 am

Properly done, a valve job should result in matching angles on the valves and seats. Lapping should not be necessary, but as Jewish mothers are so fond of saying..."it can't hoit!"

HingsingM37 · Post by **HingsingM37** » Wed Aug 27, 2008 10:49 am

Ahh, I see.
Thanks Lifer. Good luck with the move

MSeriesRebuild · Post by **MSeriesRebuild** » Wed Aug 27, 2008 2:50 pm

HingsingM37 wrote:Ok, I always thought that after a valve grind whether it be tri-angle or single the valves should be lapped in with Clover compound to ensure a good face to seat mating? Opinions?

I'll have to disagree with Lifer on this one. Valves require lapping to the seat surface always. You will not get a good seating valve if you don't lap. This will result in poor engine performance & a strong possibility of burning a valve because of a leaking seat to valve face surface.

HingsingM37 · Post by **HingsingM37** » Wed Aug 27, 2008 5:22 pm

I seem to recall always using the compund to lap any style valve job myself. Although I talked to a few folks who are of Lifer's opinion, hence my confusion and the reason for my post. Thanks Charles.

uglyranger · Post by **uglyranger** » Wed Aug 27, 2008 6:03 pm

Check out this discussion:
http://www.eng-tips.com/viewthread.cfm? ... 885&page=1

Lifer · Post by **Lifer** » Thu Aug 28, 2008 4:55 am

Thanks, Charles.

I'm not too old to adapt myself to new ways of doing things. Your answer makes sense, so I'll retract my former statement and add it to my still growing mental data bank of mechanical lore.

Juan · Post by **Juan** » Thu Aug 28, 2008 5:44 am

Awh, I thought about lap dance when I read the post subject.
I'm dissapointed.

HingsingM37 · Post by **HingsingM37** » Thu Aug 28, 2008 6:33 am

Ranger, Thanks for the post to the discussion. Seems it is a split decision with folks on this issue.
Charles, I will be lapping

Juan, if I had a single $ a lap dance would be in order! However I throw all my dollars at the truck now

MSeriesRebuild · Post by **MSeriesRebuild** » Thu Aug 28, 2008 8:14 am

To better explain my opinion here, you can see tiny rays of light around the valve face & seat when light is shined into the intake & exhaust ports. Try it & you will see it's true every time. Lap the surface good & no light will be visible. This is simply a short cut some builders choose to get by with, but not my style.

TRACTORg25 · Post by **TRACTORg25** » Tue Sep 02, 2008 7:21 am

For a propperly seated valve you will need to hand lap irreguardless of wether three angle or single. Each valve should be lapped to its matching seat. This will remove any small high spots or grinding grooves left over from the stones. Also the lapping compond must be cleaned from both valve and seat to prevent premature valve burn. Some hot rodders will disagree in that you do not need to hand lap valve on thre angle. However , most of the time there engines only run a short time period before being disassembled and rebuilt. From my experience as a heavy equipment technician and hobby of rebuilding old farm equipment I all ways hand lap after grinding.

To Lap or not to Lap?

To Lap or not to Lap?

Re: To Lap or not to Lap?

valve lapping