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Discussion Starter · #1 ·
Hi Guys

I'd like to know how you guys out there go about lapping your
valves


QUESTIONS:

How close can one get to perfectly sealing the valves ?
Is it possible to have a completely sealed valve?

What's the BEST way to lap a valve and know that you got a good seal?

I respect and appricate all you suggestions and comments.

Thanks guys
GOD BLESS

Schooner
 

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Get a valve lapping suction cup.

Get some Valve lapping compound (package of course and fine or fine and medium available at auto zone Napa and Kragen etc...)

Get some valves to lap.

Wire wheel the carbon and gunk off the head and the sealing area and the stem.

Stick the valve to the suction cup.

Spread a tiny bit of grinding compound onto the edge of the valve.

WD-40 the stem and insert into the head and like making FIRE, spin it back and forth!

Lifting and turning every 3rd or 4th twist, etc...

Once the valve and seat look to be cut equally cirrcular you are done.


FE
 

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Discussion Starter · #4 ·
On 2006-11-06 23:30, FEandGoingBroke wrote:
Get a valve lapping suction cup.

Get some Valve lapping compound (package of course and fine or fine and medium available at auto zone Napa and Kragen etc...)

Get some valves to lap.

Wire wheel the carbon and gunk off the head and the sealing area and the stem.

Stick the valve to the suction cup.

Spread a tiny bit of grinding compound onto the edge of the valve.

WD-40 the stem and insert into the head and like making FIRE, spin it back and forth!

Lifting and turning every 3rd or 4th twist, etc...

Once the valve and seat look to be cut equally cirrcular you are done.


FE
Hi Guy

Here's what I just read on an e-mail my friends friend wrote me.
He said, " Being that you've got stainless steel valves and harden seats. After the machine shop ground your valves. Now, you first get Prussian Blue die at a Napa store and coat the harded seats with the die.
Then put fine compound on the valve edge and spin,twirl the section cup back and forth. Applying slight presure as you're dong this procedure. Also, lifting up the section stick once in awhile to change the direction of the twirling. After awhile stop and look at the edge of the valve.
If there is a gray ring around the seat of the valve and its in the middle of the valve seat ~ you've got a good seal.

That sounds pretty good to me. What do you thins guys ?
Thanks for all your impute.

Schooner
 

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If you have good eyes you do not need blue dye. At my shop we use a blue ink pen... Sometimes I don't use anything.

Those directions are good and are essentially what I already told you.

Useing fine coarse or medium will not matter in the slightest. Period.

Once you get the seat ground and you have a full and perfect gray circle of area where the valve and seat contact then you are OK. It does NOT have to be in the middle of the valve, but it is safest that way.


FE
 

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Discussion Starter · #6 ·
On 2006-11-07 01:19, FEandGoingBroke wrote:
If you have good eyes you do not need blue dye. At my shop we use a blue ink pen... Sometimes I don't use anything.

Those directions are good and are essentially what I already told you.

Useing fine coarse or medium will not matter in the slightest. Period.

Once you get the seat ground and you have a full and perfect gray circle of area where the valve and seat contact then you are OK. It does NOT have to be in the middle of the valve, but it is safest that way.


FE
Hey FE

Gotcha, and THANKS AGAIN.

Schooner
 

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If the valve seat and face for the valve were ground accurately and smooth, the lapping process ought to consume no more than 30-60 seconds per valve. Takes longer to clean off things and find the supplies than to accomplish the task.

I began lapping valves as a matter of practice after hauling in a cylinder head to a shop, an while they were still sitting on the bench, I could see light across the faces. The machinist was commenting on how GOOD their equipment was. He thought it light refraction. Yes, you could see light across the face to three of the valves at the seats. I took a cup of water and poured it into the combustion chamber and it seeped right through in to the port. "If such a good seal, why does water go through?"

But those valves had some sort of automatic lapping done. No need to be done via hand. Machinist said to just mount them up and I will be happy for years. Sure.....

Never, went back there again, 'cept to pick up my re-machined heads. Boy, did they have a whole bunch of excuses as to why that happened.

It only takes a few minutes but the Secrets to valve lapping are few as others have explained here already. When getting a valve job for the heads, ask if they Lap in the valves by hand or let some machine do it for them.


Wm.
 

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Coosbaylumber,
you are so right. I used to lap my valves as described above but if you accurately grind the valves and seats (I like a good three angle job) then you can check the seal by putting some Prussian Blue on the valve or seat and drop it onto the seat. lift it of and where the blue has been pushed aside is the seal. If that ring is .015" wide on the exhausts and .010" on the intakes you are good to go!
If you do lap your valve you are actually making a groove that interupts the flow at very small openings - and that is where you want the suction to start that column of air and fuel moving into the cylinder. I don't lap valves unless they don't seat properly - I just check them.
Paul
 

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Making a groove by lapping valves??? BS...

Something is terribly wrong if you have lap them enough to make a "groove"...
 
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