Clover Lapping Compound

[PackardV8]

So no rotation of the valve required?
It's concentricity, width and placement I'd like to see.

My mentor, Bo Fields, told me sixty years ago, "Ya gotta realize, when the engine is running a valve never seats in exactly the same place twice."

So measure valve stem to face concentricity, measure guide to seat concentricity, but trying to correlate the two when assembled is a different thing.

[1980RS]

I use tooth paste form the dollar store. Nice, gritty and cheap but it works.

[hoodeng]

These days i trust seats off the Contour more than anything previously. As Tony said, valves move around the seat a bit.

That said, if i am just going to give a valve a lick on a run seat to satisfy myself i use straight Silicon Carbide grit. Easily obtained from any Lapidary supply house, this is the base of pretty much any lapping paste. Grit size is your choice, i have used a dab of 180g for years, a dab mind you not a plastering, all i am looking for is confirmation. I had tried other finer grit sizes, these did not give what i wanted, so 180g it was.
But we could be just scratching up what was a perfect seat if it has just come off the machine.

It used to cost about $20 for a pound/500g, mixed with honing oil, perfect! I also change my tube of blue every Christmas, just like every grease nipple and oil pot in the workshop gets a gift.

Cheers.

[skinny z]

We all can see what going on here.
Lapping compound: Yes. No.
Magic marker.
Layout dye.
Toothpaste.
Do nothing as lapping has no value.
Lapping has value for confirmation.
And in all truthfulness, I expected nothing less.

FWIW (and I'll bet that's not much), I'm no stranger to any of this. But every now and then I think to ask those with experience beyond my own to sort of expand my horizons so to speak.
The notion of any type of lapping compound being prohibited in a given shop was a bit of a revelation (although I did read that response in a similar post).
That said, I'll start with the least aggressive approach and see what I get. If the omnipresent sharpie marker gets the job done, then I'm in.
As mentioned, all I'm after is confirmation of the seat width and location.

[In-Tech]

What's wrong with a simple vacuum test? It will tell you all you basically need to know if you are untrusting of a shop. Or simpler yet, throw some carb cleaner or brake cleaner in the ports.
Those valves are moving all over the place when the engine is running. It's a time factor, more RPM, less time to leak.

[skinny z]

What's wrong with a simple vacuum test? It will tell you all you basically need to know if you are untrusting of a shop. Or simpler yet, throw some carb cleaner or brake cleaner in the ports.
Those valves are moving all over the place when the engine is running. It's a time factor, more RPM, less time to leak.

The seal is one thing. and that's something I'll visit via the filling the ports method. (I've no vacuum system available although I could cobble together the necessary components with the equipment in the shop I would think).
But I'm also interested in the condition of the existing valve job as well as checking on the kind of work the shop did. The valve seat looks superb. Where it all fits together is what's driving my curiosity.
Really nothing more to it than that.
Lapping compound was one workaround that I'm familiar with.

[fabr]

These days i trust seats off the Contour more than anything previously. As Tony said, valves move around the seat a bit.

That said, if i am just going to give a valve a lick on a run seat to satisfy myself i use straight Silicon Carbide grit. Easily obtained from any Lapidary supply house, this is the base of pretty much any lapping paste. Grit size is your choice, i have used a dab of 180g for years, a dab mind you not a plastering, all i am looking for is confirmation. I had tried other finer grit sizes, these did not give what i wanted, so 180g it was.
But we could be just scratching up what was a perfect seat if it has just come off the machine.

It used to cost about $20 for a pound/500g, mixed with honing oil, perfect! I also change my tube of blue every Christmas, just like every grease nipple and oil pot in the workshop gets a gift.

Cheers.

Not meaning to argue,just an observation. 180 grit particle size is .003" .with a particle of that size it can show the seat /face as concentric even though it could be out by as much as .003" since the particles/grit will fill the gap and abrade both the seat and the face yet not be mated well at all. 600 grit would be much the better at a size of .0006 and even better yet would be 800 @.0004" . My .02

[fabr]

We all can see what going on here.
Lapping compound: Yes. No.
Magic marker.
Layout dye.
Toothpaste.
Do nothing as lapping has no value.
Lapping has value for confirmation.
And in all truthfulness, I expected nothing less.

FWIW (and I'll bet that's not much), I'm no stranger to any of this. But every now and then I think to ask those with experience beyond my own to sort of expand my horizons so to speak.
The notion of any type of lapping compound being prohibited in a given shop was a bit of a revelation (although I did read that response in a similar post).
That said, I'll start with the least aggressive approach and see what I get. If the omnipresent sharpie marker gets the job done, then I'm in.
As mentioned, all I'm after is confirmation of the seat width and location.

Try the dry erase marker instead. I find it works better. YMMV though.

As you I often ask questions just to see if there is anything I need to know that might influence my way of doing. It never hurts to upgrade tooling and knowledge.

[fabr]

The seal is one thing. and that's something I'll visit via the filling the ports method. (I've no vacuum system available although I could cobble together the necessary components with the equipment in the shop I would think).
But I'm also interested in the condition of the existing valve job as well as checking on the kind of work the shop did. The valve seat looks superb. Where it all fits together is what's driving my curiosity.
Really nothing more to it than that.
Lapping compound was one workaround that I'm familiar with.

Hit it with 600 or 800 grit lapping compound and clean it well. (I assume you are not using coated valves.)

[skinny z]

The seal is one thing. and that's something I'll visit via the filling the ports method. (I've no vacuum system available although I could cobble together the necessary components with the equipment in the shop I would think).
But I'm also interested in the condition of the existing valve job as well as checking on the kind of work the shop did. The valve seat looks superb. Where it all fits together is what's driving my curiosity.
Really nothing more to it than that.
Lapping compound was one workaround that I'm familiar with.

Hit it with 600 or 800 grit lapping compound and clean it well. (I assume you are not using coated valves.)

800. 1000 grit too.
And dry erase markers.
Ferrea stainless valves. Nothing special.
The whole works need a good wash regardless.

[hoodeng]

hi Fab, i am not trying to generate a seat as such, just confirming a uniform contact. As i said, just a dab is enough, the sound a seat and valve makes when they come in if they are good is almost instantaneous, you can hear it. If you are rubbing, stop, it is not right.

Like all tests, if you are capable of doing it yourself, or can trust someone, the results should always be the same regardless.

Just got a set of fuel heads sent to me that had apparently been attended to by a ......reputable shop.... seats were supposed to be 50° in and ex,, one ex cut to 45° ,inlet cut to 50° but .035" deeper than spec, [=2.8cc] when springs were removed we could see daylight past the seated inlet, knew something was up when i had to pop the in of the seat, these passed a solvent test when assembled, hate to have seen what could have eventuated after a couple of passes. And, they would have been judged by the 'last guy touched it rule'. Me.

Really, there are more ways to skin a cat than you would think, if your results give reliable repeatable service in your endeavors, stick to it.

[rgalajda]

Persian Blue or
Magic Marker . Draw a few lines and twist the valve . You can see the seat width, and location on valve.
Pop test is informative.
Non corrosive liquid for leak test. Valve springs removed. Pour liquid in combustion chamber and let it sit, to leak test.
I have my own valve equipment . Still using stones . I’m sure someone will balk at that.

A few years ago someone asked me to put their motor together ( 455 Pontiac ) after getting everything back from the machine shop. When I leak tested the valves, half of them leaked. The machine shop said they would be fine after it runs for a few minutes. I sent the heads back. This fella wasn’t who I use ,but I still talk to him to this day.

[David Redszus]

If we were to use a surface profilometer to obtain the Ra of both valve and seat, we would quickly
understand that we are attempting to mate two minature mountain ranges. Lapping with a fine compound will reduce the peaks but not eliminate them.

When the engine is fired and run for a while, those seat peaks get slammed by the valve while
seating and a new surface is formed. That is now the true sealing junction.

Valve/seat concentricity is a huge issue. If the valve in the guide is lifted slightly, can it be wiggled
side to side? If so, the valve to seat is not concentric and one edge of the valve will hit the seat,
forcing the valve to tilt, and increasing valve stem/guide wear. The tilting valve is more inclined
to bounce and will affect the valve/seat contact surface.

An interesting thought experiment is to use a CAD program to draw a seat and valve contact cross
section in separate layers, magnified 5X. Now lift the valve off the seat and tilt slightly. What does the contact area look like?

[BCjohnny]

I think the crux of the matter is whether you're trying to bring the seat, or valve, 'in' by lapping or just trying to create a witness

The former is misguided, but I'd aver we've all been tempted to do it, the latter I don't really see a problem with

Different aims, different processes, different outcome ....... and FWIW I've seen more than a few 'machinists' tie themselves up in knots with 'blueing' a seat

[skinny z]

I think the crux of the matter is whether you're trying to bring the seat, or valve, 'in' by lapping or just trying to create a witness

The former is misguided, but I'd aver we've all been tempted to do it, the latter I don't really see a problem with

Different aims, different processes, different outcome ....... and FWIW I've seen more than a few 'machinists' tie themselves up in knots with 'blueing' a seat

As stated in post #1.

More of a check to see if the old valve job was still holding up.

The objective is to observe and not correct or change anything.