Question about Intake Valve Margin when dressing valves

[Hattrick]

I am new to grinding valves and seats but want to try this myself. I picked up a nice older B&D facing machine. The question I have is about the amount of required margin on the intake valves. I am not sure if these valves have been ground before but the margin or step on them is very minimal. Is there a standard as far as how much margin the valve should have after grinding? I know I could easily get new valves but thought if the ones that I have are within spec I would just use them. Any help or advise appreciated.

 

[wore out]

What are you working with and how will it be used?

If a "parade queen"/not heavy use the intake valve margin will be FINE so long as it's not so thin it's approaching being "sharp".

If it's going to be run hard and hot, at least 0.060" or at least half of the original margin.

 

[Hattrick]

Thanks. That is kind of what I was looking for. They are not yet sharp but would likely be close when I grind them. Probably best just to get new valves. But it is a parade queen or less. I would just rather
not have to do the work twice.

 

[Mark-Ia]

We always used to grind them at 44.5 degrees.

 

[Hattrick]

So seats at 45 and valves at 44.5?

 

[used red MN]

I agree with woreout and may even go a little less. I
would say it is okay even down to .025 on an intake for
what you are going to do with it. And that would even
be okay for for an occasional couple hours of plow day.
Now the exhaust I would stick with his .060 number
and that is a bare minimum. I was never taught to
practice the half degree difference between the seat
and valve face angles and my valve jobs lasted just
fine. The main thing is getting them ground so the seat
rides near the center of the valve face. The guy that
taught me used spray graphite. A quick spray on the
valve face and then a couple quick smacks of it against
the seat holding it up slightly with your left index
finger. Then the seating location showed up real well.

 

[Janicholson]

I agree, 1/16 .0625inch would be minimum after grinding. They dont see the heat that an exhaust valve does, but they can more easily warp when thin. Jim

 

[Mark-Ia]

That's what we used to do 40 years ago in a dealership.

 

[redforlife]

Just remember, it probably not gonna
matter much on what you are
speculating, on a valve you haven't
even ground yet. If you plan to grind
them, grind them. Then decide whether
you want to use them, or replace them.
I'm sure you want to try out your new
facing machine anyways. Wouldn't hurt
to get a little experience with it,
even though you may not use the valves
once ground.
When it comes to machining, it's
always best not to take off anymore
than needed to true something up. And
that comes with a little practice.
Whether it be, you never done it
before, or using a machine you never
have used before.

As others have said, intakes are not
as technical as exhaust. Type of
engine has some to do with it too. A
lower compression, lower RPM engine,
is going to be more forgiving than a
higher performance engine, when it
comes to a questionable valve.

 

[pete 23]

If you cannot shave with the edge of the valve and seat is well down on face it will be ok for
light work, unless you are running lean. Kidding a little about the shave.

One thing though. You said you are learning to operate the machine. Never run the valve off the
side of the stone and back on while refacing. I have seen guys do that and they get corrected
immediately.

Always dress the stone with the diamond point before starting a refacing job. As for the
interference angle of 1/2 degree, it is common practice and it gives you a real good pinch point
to seal but will soon wear in to full contact. I was not taught that in engine rebuild but went to
it later on as that was being pushed in all the vocational schools around here.

Then you just slap the valve down onto the seat a couple times and see if you have a nice line all
around the face of valve.

Make sure the seats in the head are tight. If you see any sign of pitting or carbon build on the
outer edge of seat where it sit in head, it is suspect. A light tap underneath the seat with a
suitable tool, like a screw driver and light hammer, the seat must not move.

 

[caterpillar guy]

For checking seat fit after grinding. We just used a pencil marked the seat around it a few places from center to outer edge, the with valve in turned it with our fingers. If the mark was wiped out it was good if not then had to look at the reason why and maybe replace seat or change valve depending on whether the valve was good or not might replace valve if it warped. The 549 V-8 Ih truck engine was terrible about warping those elephant ear sized intake valves.

 

[pete 23]

The pencil mark on valve face is the way I was taught but I went to the interference angle method and liked it better.

 

[Hattrick]

I need to find the tool to true the stone but i resurfaced one valve knowing that they would likely need to be replaced. They were like a knife on the edge by the time they trued up. I am wondering what grit stone is best? I just ran what was on it. Seems a little course.

(quoted from post at 03:17:44 04/11/22) If you cannot shave with the edge of the valve and seat is well down on face it will be ok for
light work, unless you are running lean. Kidding a little about the shave.

One thing though. You said you are learning to operate the machine. Never run the valve off the
side of the stone and back on while refacing. I have seen guys do that and they get corrected
immediately.

Always dress the stone with the diamond point before starting a refacing job. As for the
interference angle of 1/2 degree, it is common practice and it gives you a real good pinch point
to seal but will soon wear in to full contact. I was not taught that in engine rebuild but went to
it later on as that was being pushed in all the vocational schools around here.

Then you just slap the valve down onto the seat a couple times and see if you have a nice line all
around the face of valve.

Make sure the seats in the head are tight. If you see any sign of pitting or carbon build on the
outer edge of seat where it sit in head, it is suspect. A light tap underneath the seat with a
suitable tool, like a screw driver and light hammer, the seat must not move.

 

[Hattrick]

I ground one of the valves and by the time it was trued up it was almost sharp on the margin. I will need new intake valves for sure. I am also curious what grit stone would be best? On the one valve that I did it was not as smooth as I had hoped but probably me just being critical. The valve refacer I have is missing the bit for the truing stone so I will need to source on of those too. Any recommendations on a good place to find quality valves? I have been real happy with parts that I have bought from YT but just wanted to check. I prefer quality over price.

 

[Fritz Maurer]

You need not only the diamond, but you need the
jig to hold it. The Diamond is easy, but black and
decker valve machine parts are scarce. If you could
post a picture, that would help to identify it. The
wheel that is on it is probably the correct grit, since
it is a stepped wheel and not readily replaced with a
universal wheel from the hardware store. I run a
220 grit and am happy with that. As far as your
knife edge results, a couple different things can
cause that. The valve is bent, the stem is dirty, the
collet gripping the worn part of the valve, or the
angle is incorrectly set on the machine. I go years
and years without ever seeing a sharp margin ;
even the worst valves clean up within a few
thousandths of cross-feed travel. When setting up
your machine for a particular angle, remember that
intake and exhaust valves in the same motor can
be different angles. So its best to assume nothing,
when switching from intake to exhaust. Make sure
the valve is running true; take the collet assembly
apart and make sure it is clean, undamaged, and
lubricated. Clean the valve stem with sandpaper,
mainly so you can see where the worn part of the
valve stem is, and clamp the outer collet jaw just
past the wear line on the unworn part of the valve.
Use coolant if you have a pump. Water if nothing
else. This will help keep the wheel from plugging,
produce better work, and keep all the grit away from
the precision parts of the machine.

 

[Fritz Maurer]

As far as service parts are concerned, your best bet is probably eBay. To expand your options, type in Van Dorn and see if it looks like your machine. Black and Decker owned Van Dorn in 1945 so they were the same machine for awhile.

 

[Hattrick]

From the pictures online of the model I have my holder for the dresser is not original. They sell them on e-bay like this one. You put it in the chuck for the valve and use it as the guide. I will try and post a pic of what I have.

 

[Hattrick]

Here is the tool I found in the tool box that I think is the holder that can hold the bit to true the stone.

 

[Fritz Maurer]

Thats it exactly. Loosen the collet and push it all the way in until the fork locates on the stud of the spanner nut for your angle adjustment. The Diamond is in a 3/8ths slug about 3/4 inch long. I believe I got mine from production tool in Cleveland. Did you get the whole cabinet, or the bench top model?

 

[Hattrick]

I got just the grinding unit but then he gave me a huge Kwik-Way box with all the stones, guides, dresser and a bunch of valve guide cutters. Oh and also the drill driver. I gave $200 for the lot which I thought was a good price for juts the refacer. The box of tools is likely worth twice or 3 times that! Sometimes you get lucky. I also bought a complete Kwik-Way Model M seat cutter with all of the cutters awhile back but have not yet used it. I have a cub that needs a couple of inserts. Cool old tools.

 

[Fritz Maurer]

Would you mind posting a picture of the other side? Mine was missing part of the micrometer stem grinder, want to see what it looks like. If a guy told me $200 for that lot, think I would sprain a finger trying to get the money out of my pocket fast enough.

 

[Fritz Maurer]

Incidentally, if you have the stuff for grinding the seats, there should be a diamond to dress those wheels too. Dont know what kwik-way looks like, but I used my threaded Sioux diamond for awhile, wrapping a pop can shim around it so as not to mess up the threads with the thumb screw.