Valve seat contact area & cyl inspection

[Pablo]

Edit: title should say CHAMBER not cyl inspection..

Have my heads apart and want to see how good the valve job has held up (or was to begin with) so I marked up the seats with black magic marker and turned the valves some to look at where the contact is.
What is the preferred method? Spinning them all the way around or just 1/8th turn? I read somewhere to only turn it 1/8th.

What am I looking for exactly? It seems like a lot of the intake valves have a very narrow contact area.

The other thing I noticed is that it seems like my passenger side head ran hotter than my drivers side head. Especially the #6 cylinder. I have polished chambers and you can see significant discoloration from the heat on that cylinder. The exhaust valve also seems to have a baked on layer of deposits on it (the other valves are clean)

Is this a common air distribution issue? Or is this related to running large amounts of methanol in a manifold not designed for wet flow? I am running the power plate btw.

 

[turbofabricator]

Post a few pictures.

 

[Pablo]

a few picts. You can see the ex valve in #6 with some baked on deposits. You can really see the difference in temp if you look at the discoloration leading out from the ex valve with a hot spot right on the edge of the spark plug threads. Most of the other cyls dont have this.
The witness mark on that one seat is from spinning the valve all the way around. I just recently tried by just spinning it 1/8th of a turn and there must be some high spots because i dont get full contact on all of the valves but it seems pretty close. Any thoughts or advise is appreciated.

 

[87GNSteve]

Use some fine lapping compound to see where the seats and valve faces are. The marker will give you a general idea but lapping them will show better and can correct small blemishes/high spots.

 

[Pablo]

Thanks for the reply

An update: I installed some of the valves with springs on the head and found that I have a small amount of light shining through on the #6 exhaust valve. I turned off the lights in the room and put a small flashlight in the exhaust port and could just see some light coming through. The rest of the valves seem to be good.

Now I'm glad you mentioned lapping, I'm not sure I've ever done it properly (I only did it once before a long time ago). Can I correct the #6 ex issue with lapping? I am reading a lot of people speaking negatively about it (on speedtalk) but without any specifics. Can you elaborate on what to do? Just spin it and lift a few times?

 

[charlief1]

If light is coming through you need a valve job. What I do to check how the valve is seating is put one finger under the stem and slap the valve up and down on the seat. This will leave a slight mark on the valve and the seat if everything is clean and you can see where it's contacting. Sounds like the seat may have been a little narrow and got burned.

 

[cruzn57]

clean-clean-clean

seats and valve MUST be clean, or carbon can hold the valve off the seat.
as charlie said, tap the valve down with your finger, repeatedly, to see the seat mark.
spin it while slightly open to ck for bent valve, put some chalk on the valve face , spin slightly, it will show the location
of the seat, machinest bluing on the valve face will work better,

lemme know what it looks like

 

[Pablo]

what is the preferred method of cleaning the valves? The way I did it was I chucked them into my drill and held a red scouring pad on them while they spun. The valve in question does look like it has some deposits still on the seating area. I hope I didn't screw anything up cleaning them this way.

 

[cruzn57]

I usually glass bead mine,

I doubt you hurt it,
is the seat clean?

 

[Pablo]

Looked pretty clean but I will have to pull it apart to double check. Do you glass bead the heads too? Is there an alternative way of cleaning the seats?

 

[cruzn57]

do not glass bead the head!.
wire brush, and chemical cleaner. carefully!

 

[charlief1]

do not glass bead the head!.
wire brush, and chemical cleaner. carefully!

A wire brush in a drill will work but be careful. It can cut the seats sometimes. I have used a wire wheel on a grinder to clean the valves before with good results, but make sure you have a good grip on the valve. It can be sent accross the room if the wheel grabs it.

 

[Pablo]

Yeah I actually cleaned it with a plastic bristle brush in my parts washer with "purple power" degreaser. I cleaned the chambers with some oven cleaner to get the carbon off but I didn't let it get on the seats or anything although I don't think it would harm them (doesn't seem to do anything to ferrous metals)

I just got back in from tinkering in the garage and I think the heads need to be redone. It seems like I have too much valve guide play on that valve, and as clean as I could get the valve and seat I can still see light in one particular spot. I also did the tapping technique with some magic marker while it was still wet and could see that the same area of the valve seat where light is coming through was not touching the valve.

Pretty bummed about it.

 

[Pablo]

btw you guys talking about a steel wire brush? and what chemicals do you normally use to clean them?

 

[charlief1]

I'm talking about a steel wire wheel. I will dunk them in old gas in a bucket and flip them after 24 hours. Stinks like crazy but dries the gunk out. After that it pretty much falls off with a little pressure and a had held wire brush.

 

[Chuck Leeper]

My $.02...

A couple comments:
1.Depending on the blast media, air psi, there could be particles imbedded in the stems. This WILL destroy the guides and stems. [Very common on titanium valves.] Full strength ZEP version of "Purple Stuff" is what I use.
2.Once clean and ready to check, I always chuck the valves in a drill motor. This will tell you real quik if they are bent.
3.Once the valve job is done and the head is assembled, I put it chamber down on a sheet of masking paper, shoot a "spritx" of WD in each port. WD, with it's unique ability to "sneak" into tite places, you will quickly see just how well your valve faces and seats match.
4. The comment about NOT blasting the heads...X2!

As for #6...Poor air distribution from a ft mt throttle body can/will put more air flow to the rear cyls, resulting in a leaner AFR. What's # 5 look like?

Back to assembling my pro stock Briggs..

 

[cruzn57]

wire brush

the best brush is a BRASS wire brush if you can fine one, its easier on what ever your cleaning.
I use brake clean from wall mart, or buy it in 1 gal cans and put it in pressure sprayer.
it loosens most anything,

 

[Pablo]

A couple comments:
1.Depending on the blast media, air psi, there could be particles imbedded in the stems. This WILL destroy the guides and stems. [Very common on titanium valves.] Full strength ZEP version of "Purple Stuff" is what I use.
2.Once clean and ready to check, I always chuck the valves in a drill motor. This will tell you real quik if they are bent.
3.Once the valve job is done and the head is assembled, I put it chamber down on a sheet of masking paper, shoot a "spritx" of WD in each port. WD, with it's unique ability to "sneak" into tite places, you will quickly see just how well your valve faces and seats match.
4. The comment about NOT blasting the heads...X2!

As for #6...Poor air distribution from a ft mt throttle body can/will put more air flow to the rear cyls, resulting in a leaner AFR. What's # 5 look like?

Back to assembling my pro stock Briggs..

#5 looks good. I was hoping that the power plate did a pretty good job of evening things out which is why I was wondering if flowing all that methanol through the manifold threw things off.

What do you guys think about oven cleaner? It seems to do an awesome job on carbon and I've used it before on SBC heads but I always had a valve job done after. Think it would harm a seat?

 

[cruzn57]

it shouldn't hurt it, as long as DO NOT allow it to etch the surface, I'd spray it, use a brush to agitate and rinse, I would not allow
it to soak or etch ,
your seats should be hardened and shouldn't be damaged easily.