valve lapping

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scooby

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so if I understand correctly your saying rub soap on the head? Do I focus heat on the head around the cage, on cage, or both?
 

Steamchick

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Yes, the fat in the soap will char with the alkali..... at somewhere around 200 to 250C. (I think!). This is above the char temperature for the loctite. Just warm the whole job, not any specific zone.... (I reckon. You'll soon tell me if I am wrong!). As I don't have your head and valve seats I can't try it for you..... hot air gun should be fine....
Take care whatever you do.
K2
 

scooby

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Tried using toothpaste, but I think I'm gonna try this: McMaster-Carr
and then use toothpaste if needed.

When using toothpaste, how often do you do wipe off/clean from valve and put new toothpaste on it? After a couple minutes of lapping?
 
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JohnBDownunder

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For what it's worth, here in OZ some of us use "Gumption cleaner". It's a mildly abrasive household cleaner that rinses out / off with water.
To be fair, some use various grits of lapping compound be it a diamond or carborundum grit.
Personally, I use the Gumption cos I'm cheap and it's in the laundry cupboard. Probably replenish it a bit less frequently than toothpaste and it works for me.
John B
 

minh-thanh

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Hi scooby !
The first : make sure the valve and seat are "relatively "concentric
Use a grit size of about 600, 800... this depends on the surface of the seat and valve when you do it. The time for this lapping is also more or less depending on the surface. For me, this step only has the effect of "shaping the contact surface" of the valve and seat . So it doesn't take much time and, again it depends on the surface
If, when the above step is completed, lapping valve and seat with a size smaller : 1800 or 2000 or ... . Just these 2 steps are enough
If the valve and seat have very few leaks, use toothpaste
The above steps do not need to change the material used for lapping often, just change it when it "feels" like it is no longer effective. With toothpaste, only change it when it starts to change color
A question : is this your first IC engine ?
 

David Shealey

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Yes, the fat in the soap will char with the alkali..... at somewhere around 200 to 250C. (I think!). This is above the char temperature for the loctite. Just warm the whole job, not any specific zone.... (I reckon. You'll soon tell me if I am wrong!). As I don't have your head and valve seats I can't try it for you..... hot air gun should be fine....
Take care whatever you do.
K2
You do not need to "char" Loctite to seperate parts. Loctite will soften (it is a polymer), and make it easier to separate parts at a much lower temp. I have removed many parts, bearings, bushings, screws and nuts, by heating just enough for the Loctite to soften and make removal easy. Never to a point where anything would char.
 

scooby

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I've done some other of Jerry Howell's engines. Beamer stirling, Bill 1906, and Powerhouse. I've spent much more time working on the v4 then the others and want to make sure I get everything right instead of dealing the the disappointment of a non-starting engine. I get much more enjoyment out of making things rather than putting things together. Give me a blueprint dimensioned correctly, and I'm happy.

My heads were dirty so the soap will help clean them anyway :)
 

scooby

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How do you quote someone and and put it in your reply? I tried clicking on the persons quote, and wrote in the box on the bottom, and nothing shows up when I post
 

minh-thanh

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First: "quote"
Then " insert quote "
After :
Untitled.jpg

And. :
You can delete some in " quote "
 

scooby

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Tomorrow I'll have some of the higher grit lapping compounds (2oz this time)

Right now the ends of the valve cages are 90 degrees (bored the inside of them and when pulling out of hole used same boring bar to face end of it)

Do I use the valve seat cutter I made and do a couple hand turns to get a small bevel on the cages and then apply the lapping compound to the valve?

Or do I NOT use valve seat cutter and just use lapping compound on it? (I tried this on a test pieces and I get a line of contact on valve)
20211123_195038_resized.jpg


I've been using isopropyl alcohol with a q-tip to wipe off the lapping compound to clean the cages and valves. Should I be using liquid dish soap like mentioned before to clean this compound off or can I just use the isopropyl alcohol or mineral spirits to clean the compound off?

I really do appreciate all the help you have all provided me
 

minh-thanh

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Hi !
 

scooby

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Hi !
If drawing calls for a .015 seat, is that .015 dimensioned at A, or at B?
VALVE SEAT.jpg




I should use spirit initially, then soap and water. An ultrasonic cleaner ($20) is cheap and effective to clean these things well with a drop of detergent in the water bath. Uten 600ml Ultrasonic Cleaner Timer Jewellery Coins Cleaning Machine With Basket | eBay
K2
When using an ultrasonic cleaner, do you clean parts every time you change grit size, and how long do you keep in the ultrasonic cleaner for?
 

scooby

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Previously I had not cut seat in cage, just put 600grit lapping compound on valve and lapped. This made a single line of contact on the valve.
I re-cut the 45 deg on test valve to get a fresh surface. Then used valve seat cutter to make small bevel on test valve cage (still don't know if A or B is right from previous post). I put on the 600grit lapping compound and moved valve back and forth against cage about 10 times, lifted off, rotated and repeated a few times. That made a line of contact like the first time, but thicker. Are the lines of contact supposed to be noticeable on the valve after lapping, or is the 600 grit too course to start off with

20211124_141210.jpg
 

Brian Rupnow

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600 grit will leave a visible contact ring completely around the valve face. Using toothpaste for lapping might work if you live long enough. --The "grit" in toothpaste is about 2000 ---Fine for teeth, rather useless for steel.
 

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