Valve job with stones

[steve cowan]

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I really want to learn how to do my own valve jobs as i want to experiment with different angles.i had a bad experience with my machine shop at Christmas which ended up with a pair of ruined heads at my expense.
Ultimately i want to purchase a good quality mill to do valve jobs and milling decks,obviously there is a huge expense to pursue this endeavour.
A friend has a old set of stones so we done a couple of exhaust seats at 50deg with a 37deg top cut.
When you look at the photos the seat is rough in texture and the top cut is only just with a bit of the 30deg top cut still showing. Does the rough seat matter??
We done the valve at 51deg on a valve grinding machine.
The biggest thing I found is the port had zero turbulence and I mean zero,every exhaust port I have done has had some form of turbulence over 28" depression.
This port was smooth and quiet from 200"-700" lift.i tested up to 45" and have flow numbers if anyone is interested but I am more interested in the seat profile comments.
Thanks in advance,

[benno318]

i still use stones regularly myself, what kind of stone holder are you using, W&B? what are you driving it with?

i use W&B holders which have adjustable "pressure" (basically a slip clutch type deal) however i never actually use it this way, i just vary the speed and/or pressure i exert on the stone. dress regularly for best results.

i use a die grinder to drive them, no side load. mainly use the stones for the quick daily driver repair type jobs more so than performance work, however they are more than capable of performance - just takes time and care to keep all seats the same.

recently i had a customer drop off his LS3 heads that he races in production car circuit racing - "need more power" he says. well i looked over the rules, and there wasnt a lot that could be done - the worst was the wording "it is permitted to re-grind a valve seat provided that the grinding process doesnt remove any of the original cylinder head casting material"
none of my newen valve seat cutters would have cut the seat without touching aluminium. so i took the time and did a 6 angle job with stones.
between that, correcting uneven chamber volumes, and advancing the cam a touch, we picked up 20-odd peak hp but almost 40hp in the midrange.

most people seem to bag the stones out, but i wouldnt ever get rid of mine.

[steve cowan]

Benno,
thanks for your reply,a mate just bought the stone kit from a deceased estate it has the WB stone holder and we played with clutch settings,we used a battery drill to drive.we refaced the stones on a diamond grinder.the stone we refaced to 50 deg seemed to be more course than the 37deg.
I have read a lot of old threads on guys using stones with good success.i will be buying a seat runout gauge and a valve face runout setup as well.i am concentrating on the exhaust side at the moment as I think it will be easier with less sharp angles to consider.

[KnightEngines]

Drive it with a die grinder, far better finish.
Reface the stones on the valve faces for the seat contact angle.
If you have plenty of spare stones you can wet grind for final finish, degreaser works well. But stones you get wet will cut slow & load up from then on unless you bake them dry in an oven.

Stones can do a very good job, just takes a bunch of time.
Make sure your pilot is a snug fit & use a drop of oil so it doesn't gall in the guide.

Who killed the heads?
Pretty good chance I could save them if you want?

[Roadknee]

There is absolutely nothing wrong with stones. It does take care and a lot of time to get consistent quality results. I have Sioux pilots, holders, stones, air driver and a Kwikway valve refacer. Use the finishing stones, even on hard seats, to get a smooth mirror-like finish and minimal runout.

Using a seat runout gauge is mandatory. You can take your time, applying very little pressure and avoiding side pressure to grind a well-appearing seat that still has 0.005” runout. Use the runout gauge to find the high spot and gently push the stone holder in that direction while grinding. With practice you can get under 0.002” runout pretty easily and 0.001” if you work at it.

Verify your pilot is not bent before you start each job. Insert the pilot in a guide and use the runout gauge to find the high spot. Rotate the pilot 180 degrees and recheck. If the location of the high spot moves, or the amount of runout changes your pilot is bent.

I understand the majority of shops now have seat cutting machines like the Serdi, but I’m real curious how many actually know how to use their own equipment to get concentric seats. I’m currently 0 for 2 hiring shops to cut seats. One was late model Chevy heads where new seats were installed in the center exhaust cylinders and seats cut. The worst seat had 0.006” runout. For my last build I drove the Merlin BBC heads 125 miles one way to a shop with a Serdi. The owner gave me a tour. He had an assortment of live pilots, cutters, a runout gauge and certainly talked up his ability. I had him install K-line liners, hone to fit, and cut the seats. I left convinced these heads would turn out excellent. When I picked up the heads he told me the exhaust seat inserts were an older material, and the cutter removed shavings instead of chips. He said they took additional time, but assured me they’d seal fine. When I got the heads home I brought out the stones to improve the appearance of the seat finish. The stone touched off on one small side of the first seat. I had to sink the worst seat 0.010” just to get a 45 angle all around and another 0.005” to achieve concentricity. I had to sink the best seats 0.010” total. All the intake seats were less than 0.002” runout, so he has better luck cutting cast iron. The guide liner install looked good. I borrowed the proper clearance checking micrometer from a friend. Clearance on valve seal side was to spec, but most had 0.0005” taper, being larger on the seat side. He showed me that he had all the proper tools to measure his work. I guess he was just too proud to use them. Personally, I think shops should check runout on every seat they cut, or at least one intake and exhaust per head. I wonder how many really do.

[rebelrouser]

I prefer stones. First stones like any other abrasive come in different grits and materials, if you have a rough texture on the seat, the speed of the stone and the proper grit for the seat material is important to get the right finish. I have always had a valve and seat grinder in my repair shop since 1976, If I pull a head for a head gasket, it takes very little time to touch the seats up and install new valve seals. I find newer engines are very hard on exhaust seats.
https://www.cylinderheadsupply.com/valv ... sioux.html
I also like to use a lifting spring so I can get the right amount of pressure on the seat and when it releases clean that seems to make a better finish as well. When cutting the 60 degree angle if you don't use a lifting spring the stone can bind and explode so be careful.
I use Sioux seat and valve grinding equipment. I have used a Sioux wet seat grinding bench, but I get good results dry as well. And wear a mask when grinding fine dust is hard on your lungs.

And like others have said, I leak test all my seats with a vacuum tester and I see lots of new heads done with cutters that leak air, and they may run the engine, but I always was taught you don't let an engine leak any more air than you have to. My other reason for doing my own seats and valves is time, to drop off a set of heads at a machine shop takes time, and when a person brings me a car, they always ask two questions how much and how long, with my own valve equipment I can answer those two questions with a lot more accuracy.

[engineguyBill]

Grinding stones work very well for valve seat grinding. It is important that the pilots are correct size and in good condition, stones are properly faced using diamond fixture and that the seas are checked for concentricity. The seats and the valve faces should be smooth for best results.

[steve cowan]

Drive it with a die grinder, far better finish.
Reface the stones on the valve faces for the seat contact angle.
If you have plenty of spare stones you can wet grind for final finish, degreaser works well. But stones you get wet will cut slow & load up from then on unless you bake them dry in an oven.

Stones can do a very good job, just takes a bunch of time.
Make sure your pilot is a snug fit & use a drop of oil so it doesn't gall in the guide.

Who killed the heads?
Pretty good chance I could save them if you want?

Tony,
these are my 178cc cast iron darts,i asked for K-lines,spring seats cut for 1.550'' spring,stud bosses milled down,50deg valve job with angles and widths I wanted,angle mill heads to 62cc,spot face,intake manifold correction etc.very labour intensive for them but they said no probs so merry chrismas to me .
they flat milled down close to seat ring on intake,45deg standard valve job
now the heads go turbulent at 450'' lift,so i bought a sonic tester to check meat on SSR got 100'' max and its hard to measure because its not flat at the turn,if i sink the valve job i am not sure if i can get the turn correct.on these heads i just wanted to do some exhaust port work and resizing the PRP.i could send them to you they are just heavy little buggers.

[steve cowan]

There is absolutely nothing wrong with stones. It does take care and a lot of time to get consistent quality results. I have Sioux pilots, holders, stones, air driver and a Kwikway valve refacer. Use the finishing stones, even on hard seats, to get a smooth mirror-like finish and minimal runout.

Using a seat runout gauge is mandatory. You can take your time, applying very little pressure and avoiding side pressure to grind a well-appearing seat that still has 0.005” runout. Use the runout gauge to find the high spot and gently push the stone holder in that direction while grinding. With practice you can get under 0.002” runout pretty easily and 0.001” if you work at it.

Verify your pilot is not bent before you start each job. Insert the pilot in a guide and use the runout gauge to find the high spot. Rotate the pilot 180 degrees and recheck. If the location of the high spot moves, or the amount of runout changes your pilot is bent.

I understand the majority of shops now have seat cutting machines like the Serdi, but I’m real curious how many actually know how to use their own equipment to get concentric seats. I’m currently 0 for 2 hiring shops to cut seats. One was late model Chevy heads where new seats were installed in the center exhaust cylinders and seats cut. The worst seat had 0.006” runout. For my last build I drove the Merlin BBC heads 125 miles one way to a shop with a Serdi. The owner gave me a tour. He had an assortment of live pilots, cutters, a runout gauge and certainly talked up his ability. I had him install K-line liners, hone to fit, and cut the seats. I left convinced these heads would turn out excellent. When I picked up the heads he told me the exhaust seat inserts were an older material, and the cutter removed shavings instead of chips. He said they took additional time, but assured me they’d seal fine. When I got the heads home I brought out the stones to improve the appearance of the seat finish. The stone touched off on one small side of the first seat. I had to sink the worst seat 0.010” just to get a 45 angle all around and another 0.005” to achieve concentricity. I had to sink the best seats 0.010” total. All the intake seats were less than 0.002” runout, so he has better luck cutting cast iron. The guide liner install looked good. I borrowed the proper clearance checking micrometer from a friend. Clearance on valve seal side was to spec, but most had 0.0005” taper, being larger on the seat side. He showed me that he had all the proper tools to measure his work. I guess he was just too proud to use them. Personally, I think shops should check runout on every seat they cut, or at least one intake and exhaust per head. I wonder how many really do.

thanks for the feedback and information,the thing I noticed with stone is you can't see what you are doing and it is kinda guess work in a way but like most things time and experience come into play,the kit my friend has is very old but for a few grand I can get kitted up myself,probably have to learn how to replace seat rings as well

[steve cowan]

I prefer stones. First stones like any other abrasive come in different grits and materials, if you have a rough texture on the seat, the speed of the stone and the proper grit for the seat material is important to get the right finish. I have always had a valve and seat grinder in my repair shop since 1976, If I pull a head for a head gasket, it takes very little time to touch the seats up and install new valve seals. I find newer engines are very hard on exhaust seats.
https://www.cylinderheadsupply.com/valv ... sioux.html
I also like to use a lifting spring so I can get the right amount of pressure on the seat and when it releases clean that seems to make a better finish as well. When cutting the 60 degree angle if you don't use a lifting spring the stone can bind and explode so be careful.
I use Sioux seat and valve grinding equipment. I have used a Sioux wet seat grinding bench, but I get good results dry as well. And wear a mask when grinding fine dust is hard on your lungs.

And like others have said, I leak test all my seats with a vacuum tester and I see lots of new heads done with cutters that leak air, and they may run the engine, but I always was taught you don't let an engine leak any more air than you have to. My other reason for doing my own seats and valves is time, to drop off a set of heads at a machine shop takes time, and when a person brings me a car, they always ask two questions how much and how long, with my own valve equipment I can answer those two questions with a lot more accuracy.

thanks for the link,Didn't realize how many different grade stones are available,I can buy a vacuum tester here in Australia as well as measuring equipment,the bounce spring makes sense,one thing I noticed is the stones cut the seat fairly fast which I was a bit surprised with.

[steve cowan]

Grinding stones work very well for valve seat grinding. It is important that the pilots are correct size and in good condition, stones are properly faced using diamond fixture and that the seas are checked for concentricity. The seats and the valve faces should be smooth for best results.

thank you Bill,
I have seen photos of some nice finished seats done by stones,i was curious if stones can keep sharp angles on the intake port side and it looks like it is certainly possible.i can buy a new Goodson kit for around $2000 available here in Australia.

[jed]

There is a lot if good information in all the posts above. Pay attention to each post and make a list of do and dont's.
You asked does the rough seat matter. Yes it matters. The seat should be as smooth as possible and flat. Dress your stone
to keep it sharp and flat. The stone will cut faster and you'll have a flatter seat.
If you want to nit pick make sure your valve refacer and stone dresser are at the same angle. Just because you refaced valves at 45' and dress your stones at 45' don't mean they match.
Also the seat angle should be the last angle ground.
Use the pilot with the least taper you can find. Less taper will help the pilot follow the centerline of the guide. Clean/brush
the guide out before inserting the pilot.
Vacuum checking is ok but use as little a vacuum as possible. Something less than 10" of vacuum and NO valve spring.
Seat grinding can do good valve jobs. Any more it's not for a profit shop.
let us know how it goes

[steve cowan]

There is a lot if good information in all the posts above. Pay attention to each post and make a list of do and dont's.
You asked does the rough seat matter. Yes it matters. The seat should be as smooth as possible and flat. Dress your stone
to keep it sharp and flat. The stone will cut faster and you'll have a flatter seat.
If you want to nit pick make sure your valve refacer and stone dresser are at the same angle. Just because you refaced valves at 45' and dress your stones at 45' don't mean they match.
Also the seat angle should be the last angle ground.
Use the pilot with the least taper you can find. Less taper will help the pilot follow the centerline of the guide. Clean/brush
the guide out before inserting the pilot.
Vacuum checking is ok but use as little a vacuum as possible. Something less than 10" of vacuum and NO valve spring.
Seat grinding can do good valve jobs. Any more it's not for a profit shop.
let us know how it goes

thanks Jed,
we faced the valve at 51 deg,i am thinking this so the valve does not stick to the seat ring?? on a running engine.
on the photo of the valve there is a seat contact mark,we blued the seat and back blued to the valve face for a visual,i did not want to lap the valve as we could see the seat was rough in texture,again the stone kit we used was very old,seems the stones are still popular and I am willing to follow through with this.

[jed]

Just as a reminder when you dress a stone any stone the you must have a good diamond with a sharp point.

[allencr267]

Looks horrible, un-dressed or really coarse stone or dressed on the sidewalk?

I don't expect a mirror finish on some materials, but close to it on all.