Achieving Rpk , Rk and Rvk numbers during honing

[stokerboats]

When you use rtv on the intake gasket, how do you prevent the rtv from squishing out into your otherwise pristine intake/head port match? I have found that challenging at times.

[joespanova]

When you use rtv on the intake gasket, how do you prevent the rtv from squishing out into your otherwise pristine intake/head port match? I have found that challenging at times.

That would be my concern as well.....

[Frankshaft]

I prefer Mega Black from Versachem, vs Ultra Black from Permatex, but either is better than "silicone". Right stuff works too, but is more difficult to remove. So it doesn't ooze, put it on lightly. You can also leave it slightly away from the extreme edges, except on the bottom. You don't need to use half the tube. You could use hi tach, you could use a spray on sealer as well.

[joespanova]

I prefer Mega Black from Versachem, vs Ultra Black from Permatex, but either is better than "silicone". Right stuff works too, but is more difficult to remove. So it doesn't ooze, put it on lightly. You can also leave it slightly away from the extreme edges, except on the bottom. You don't need to use half the tube. You could use hi tach, you could use a spray on sealer as well.

Sounds good..thanks.

[MotionMachine]

I use my profilometer so much I wore out the stylus. There actually 7 parameters I measure. IMO, Rpk, Rk, and Rv (peak, valley and wall) are the most important. If you get those 3 where they should be, the others fall in line. I only use diamond though, the only time I tested the finish with a profilometer using vitrified (Serv-Equip AN hone) was on a SBC for a buddy who wanted to know what he was getting with his method. I did a simple 220, 280, plateau and got perfect numbers. I don't have any 400 AN stones so I can't tell you what the finish would be with them but from experience I would say that all the numbers would have been on the low end of the scale but probably still good. The numbers that are also useful are the Ra and the Rz. They compare to each other and they will tell whether the valley is too deep or too shallow compared to the peak. Too little a ratio and the result can be no ring seating causing blowby. Too much and it'll use oil as there is too much valley depth.
It's block hardness that determines different techniques. Harder the block, the finer the finish will be with any given grit. A 280 grit will act like a 400 grit on a hard block. A soft block will act the opposite. A 220 grit will give you very deep valleys on a soft block, much shallower on a hard block or ductile sleeves. Some ductile sleeves I've installed go right from a 220 grit diamond to a 500 grit, it's the only way to get any valley depth. Sometimes it's 220, 320, then 600. It's all down to trial and error but from my one time experience with testing vitrified, I'd say it's way easier to get a good finish with that than diamond.

[joespanova]

I use my profilometer so much I wore out the stylus. There actually 7 parameters I measure. IMO, Rpk, Rk, and Rv (peak, valley and wall) are the most important. If you get those 3 where they should be, the others fall in line. I only use diamond though, the only time I tested the finish with a profilometer using vitrified (Serv-Equip AN hone) was on a SBC for a buddy who wanted to know what he was getting with his method. I did a simple 220, 280, plateau and got perfect numbers. I don't have any 400 AN stones so I can't tell you what the finish would be with them but from experience I would say that all the numbers would have been on the low end of the scale but probably still good. The numbers that are also useful are the Ra and the Rz. They compare to each other and they will tell whether the valley is too deep or too shallow compared to the peak. Too little a ratio and the result can be no ring seating causing blowby. Too much and it'll use oil as there is too much valley depth.
It's block hardness that determines different techniques. Harder the block, the finer the finish will be with any given grit. A 280 grit will act like a 400 grit on a hard block. A soft block will act the opposite. A 220 grit will give you very deep valleys on a soft block, much shallower on a hard block or ductile sleeves. Some ductile sleeves I've installed go right from a 220 grit diamond to a 500 grit, it's the only way to get any valley depth. Sometimes it's 220, 320, then 600. It's all down to trial and error but from my one time experience with testing vitrified, I'd say it's way easier to get a good finish with that than diamond.

VERY GOOD , thanks for sharing.

[David Redszus]

At one time, surface profilometer readings for Ra were used almost exclusively. While still true
for numerous machining operations and materials, Ra has become obsolete for cylinder bore measurement.

An acceptable visualization of surface finish can be obtained by the use of peak height and valley depth values.
While providing absolute numbers, that does not tell us how many peaks or valleys nor their size distribution.

A much more useful measure is the use of Abbotts Bearing Curve, which provides a visual of peaks, valleys,
load bearing surface and oil retention volume.

Modern surface profilometers actually provide ten times more information regarding the surface condition.

[joespanova]

At one time, surface profilometer readings for Ra were used almost exclusively. While still true
for numerous machining operations and materials, Ra has become obsolete for cylinder bore measurement.

An acceptable visualization of surface finish can be obtained by the use of peak height and valley depth values.
While providing absolute numbers, that does not tell us how many peaks or valleys nor their size distribution.

A much more useful measure is the use of Abbotts Bearing Curve, which provides a visual of peaks, valleys,
load bearing surface and oil retention volume.

Modern surface profilometers actually provide ten times more information regarding the surface condition.

We use Ra FREQUENTLY in the commercial aircraft industry. Materials like HVOF have very specific surface requirements. As far as I know our surface gauges do not use Rpk , Rk and Rvk.

[David Redszus]

At one time, surface profilometer readings for Ra were used almost exclusively. While still true
for numerous machining operations and materials, Ra has become obsolete for cylinder bore measurement.

An acceptable visualization of surface finish can be obtained by the use of peak height and valley depth values.
While providing absolute numbers, that does not tell us how many peaks or valleys nor their size distribution.

A much more useful measure is the use of Abbotts Bearing Curve, which provides a visual of peaks, valleys,
load bearing surface and oil retention volume.

Modern surface profilometers actually provide ten times more information regarding the surface condition.

We use Ra FREQUENTLY in the commercial aircraft industry. Materials like HVOF have very specific surface requirements. As far as I know our surface gauges do not use Rpk , Rk and Rvk.

What information do you get from Ra measurements?

[joespanova]

At one time, surface profilometer readings for Ra were used almost exclusively. While still true
for numerous machining operations and materials, Ra has become obsolete for cylinder bore measurement.

An acceptable visualization of surface finish can be obtained by the use of peak height and valley depth values.
While providing absolute numbers, that does not tell us how many peaks or valleys nor their size distribution.

A much more useful measure is the use of Abbotts Bearing Curve, which provides a visual of peaks, valleys,
load bearing surface and oil retention volume.

Modern surface profilometers actually provide ten times more information regarding the surface condition.

We use Ra FREQUENTLY in the commercial aircraft industry. Materials like HVOF have very specific surface requirements. As far as I know our surface gauges do not use Rpk , Rk and Rvk.

What information do you get from Ra measurements?

Boeing and liaison engineering tell us what they what , and that's what they get . If they require greater "specificity" it would be part specific. On parts I see frequently , either static or dynamic , that's all they require.

[zums]

You can get different numbers across the board using the same grit stone, stroke , rpm speed, stone pressure, lube,, lots of variables, didnt see anyone ask how low the tops of your guides are and how is your top end drain back, external lines?, it takes alot less oil then most think to flood the top of the guide, dont matter what seal is on there it aint meant to work completely submerged, do you declutch at end of track or wind it down
Tom

[joespanova]

You can get different numbers across the board using the same grit stone, stroke , rpm speed, stone pressure, lube,, lots of variables, didnt see anyone ask how low the tops of your guides are and how is your top end drain back, external lines?, it takes alot less oil then most think to flood the top of the guide, dont matter what seal is on there it aint meant to work completely submerged, do you declutch at end of track or wind it down
Tom

zums..the guides aren't low. They'd be what I would percieve as typical SBC height.The seals are the good Comp ( gold metal body , light blue seal w/ retaining spring).Not the cheap white P.C style seals. How did you figure I have a clutch? LOL
I "clutch and dump" immediately thru the traps.
However , all this has me wanting to rethink how I'm pulling vac . at covers.

[zums]

You can get different numbers across the board using the same grit stone, stroke , rpm speed, stone pressure, lube,, lots of variables, didnt see anyone ask how low the tops of your guides are and how is your top end drain back, external lines?, it takes alot less oil then most think to flood the top of the guide, dont matter what seal is on there it aint meant to work completely submerged, do you declutch at end of track or wind it down
Tom

zums..the guides aren't low. They'd be what I would percieve as typical SBC height.The seals are the good Comp ( gold metal body , light blue seal w/ retaining spring).Not the cheap white P.C style seals. How did you figure I have a clutch? LOL
I "clutch and dump" immediately thru the traps.
However , all this has me wanting to rethink how I'm pulling vac . at covers.

Straight oiling lifter, edge orifice, any restricters in the block, pushrod hole size, you relying on oem drainback path?
Tom

[gunt]

I've seen this is a poorly executed valve guide job , on a particular model of head and several of they by different shops , but there were huge arguments by everybody and when I pulled a head and got it done myself by my guy , the issue stopped therefore it could only have been the guides regardless of 2 sets of new seals ,

[joespanova]

I've seen this is a poorly executed valve guide job , on a particular model of head and several of they by different shops , but there were huge arguments by everybody and when I pulled a head and got it done myself by my guy , the issue stopped therefore it could only have been the guides regardless of 2 sets of new seals ,

Well , the heads are at Bischoffs as of today. If there's a problem it'll get caught.