Lapping the valves

I bought a new head and all new valves and springs for one of my tractors. Do people still lap new valves in or was lapping pretty much a technique used to get a few more miles out of a head. Do people still use gear bluing and fit them in that way?
I'm just wondering what others here do before I go ahead and assemble this thing. I've always just taken my heads in to the machine shop for a valve job and torqued them on when they were done.
Thanks

Send it to the machine shop to mate the valves with the seats.
The can of grit,a stick and suction cup.Is a low priced stop gap measure to get an engine to run a little longer.

The problem with lap grinding valves is that it makes the valve seats too wide.
Have it done at a machine shop where they can do a three angle valve job to get the seats the right width and in the correct location.

Using the bluing or lapping will tell you if they are seating properly and how wide the seat area is. I'd do it !

He said he has a NEW head and NEW valves. I highly doubt he is going to "grind" away much with lapping compound. Everything should be good with new parts , but you still need to check them.

Lapping compound works great as a marker. When you"re in the process of grinding/cutting, and narrowing seats, a quick lapping will show you exactly where they are, how wide and also any imperfections. If you"ve done a proper job of narrowing with a two of three angle cut, using lapping compound won"t hurt a thing. Not even with interference angles. Just gives you some insurance that all is right.

Lapping is one of those misunderstood words. Lapping is a step in seating valves when having seats cut or ground and valves faced. When lapping is used instead of grinding the seats and valve faces it is really not a good band aid.

I always spark face new valves. Every now and then I find a new valve that will not spark 360 degrees. I spot blue valves to the seats. Having all new parts does not mean that you will automatically have a perfect fit.

Exactly what I said. Until the seats are ground to the proper width and height. For durability if nothing else.
He didn't say gas or diesel either. If the diesel has the valves sitting too proud of the head's deck. There will be a bad sound as the valves and pistons meet.

UD:

To answer your specific question: No, few folks still lap in new valves or even check fit with bluing (outside of HP engines) but not because either is an archic or non useful practice but rather to avoid spending the time necessary to so do.

Dean

You do not even have to use anything as coarse as "Lapping Compound" to check..

You can use good old rubbing compound, or even Polishing compound..either will leave a discernible mark and finish for you to verify the seating and seat width..
Are you positive the head is actually ready for valves to be dropped in..??
Actually, I would be surprised if it is "Ready" for valves..
I myself grind each valve and seat to be a perfect match and I need no spring pressure to see a full 360 degree "touch" on the seat..
You don't see that from NAPA...!!!
Ron..

Thanks fellows.
A friend of mine works at a machine shop and I will borrow a little bluing from him tomorrow. At least check how well the valves are seating and go from there.

i agree 100%...the new components need to be cut to match each other and lapped in to finish the seal...no such thing as parts being ready to put together just cause theyre new.

(quoted from post at 22:54:21 03/22/10) I bought a new head and all new valves and springs for one of my tractors. Do people still lap new valves in or was lapping pretty much a technique used to get a few more miles out of a head. Do people still use gear bluing and fit them in that way?
I'm just wondering what others here do before I go ahead and assemble this thing. I've always just taken my heads in to the machine shop for a valve job and torqued them on when they were done.
Thanks

Click to expand...

I have always did my own valve work,,, always lap'em,,, most of the time spray the seats with the blue chit so I can see how wide the seat is when done lap'n,,, even then go back a leak check with fluid and air...

Just installed new seats and valves in a N block,,, cut the seats lapped the valves,,, after I installed them with valves closed pored a little varsol on each cylinder valves closed and looked for leaks thru the ports,,, even blew a little air at the bottom of the valve,, I hate to get beat when I am this close to it....

Back around 1992 I thought I was good,,, installed a head,,,,had a leaker after that I confirm it while I am close to it :wink: its a over kill but I don't mine doing it,,,, my machine shop man either hates me are likes me dunno,,, I recheck and clean every thing behind him....

I started out wranch'n in a shop were they did their own head work,,, bunch of old timers that were old school,, shops use to do their own valve work but its a lost art.... I have sent heads out for seat work ,,, machine shops make a lot of mistakes you have to recheck their work,,, they also think they are to good to fudge up

FWIW, General Motors recommended their dealer shops to discontinue the practice 40 or more years ago.Their reasoning was that no matter how hard you try, you can never get all the compound off. As a result the compound keeps cutting which shortened the life of the valve seal.FIL was a service manager back then. Two things he insisted on was no lapping compound and all valve guides were to be knurled.

Is that a Ford 3 cylinder diesel head?

You can make a series of marks all the way around the valve face with a common #2 pencil, then drop it in the head an rotate it, then have a look at the marks to see how it's seating and how wide the seat is.

I learned that method at Cummins Diesel service school many years ago.

NO special goo needed and NO grit. Give it a try!

Yes.
4600D. I'm putting it on a 4000 gasser. Go figure