Valve job with stones

[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.

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.

The bump spring will help with that, you can control how much pressure you put on the stone. Most of the time I just give them a quick blip, and then look at them to see how much grinding I will need to do. Most heads with hardened seats a quick blip is many times all that is needed. One other tip is you can use a lot of things to mark the seats so you can see the angles better, but I just use a black magic marker, cut the 45 degree mark the seat, and then hit it with a 30 and then a quick blip with a 60, the black line left is the seat, all engines will have a spec for seat width.

[modok]

Air drivers have less kick, and may be easier to control speed. I don't generally use a spring.
I WOULD use a spring if using an electric driver.

A holder that is a very tight clearance on the pilot will cut smoother and produce far less runout.
Looser fit will cut more aggressively.

[steve cowan]

Air drivers have less kick, and may be easier to control speed. I don't generally use a spring.
I WOULD use a spring if using an electric driver.

A holder that is a very tight clearance on the pilot will cut smoother and produce far less runout.
Looser fit will cut more aggressively.

hi Glen,
thanks for your input much appreciated.
I had chatter on the seat because of old rough stones and yes the stone holder was a bit loose on the pilot as you said,Again I am just trying to get my head around it as this was the first time I have ever touched a valve seat.
I really do appreciate everyones advice so far,I will be ordering a new box of goodies tomorrow.
Warren and Brown setup with air driver,pilots,stones, diamond sharpener,stone holder and tool box is $1650 plus GST here in Australia,i would need different finishing stones and different angles as well.

[benno318]

pm sent steve cowan - not sure if allowed to plug a sales company on here...

[1980RS]

Stones must work. My car with stock heads goes mid-11's with 45° valve job and I still don't know what I'm doing. One thing I do it and I know some here don't like this step but I still lap all my valves in after grinding. Not sure if it hurts or helps but a head porter up here said it brings the engine right up to power lapping in the valves. He must know, most of the stuff he races is in the 8 sec zone with really small cube engines.

[BCjohnny]

I always use a bounce spring, and put light pressure to 'kiss' the seat and get back out fast .... you will have to do this several times to bring the seat or angles in

Not using a spring can be a recipe for disaster, and can get you into trouble fast .... especially when learning the ropes

Be careful with die grinder speed ..... depending on stone diameter speeds of 9000 - 12000 rpm for what you're doing is ballpark ...... die grinders can go 30k +

Most 'aftermarket' units are basically angle grinders with an adaptor, due to their entirely appropriate speed rating, if looking a little ungainly to use

Now the controversial bit :

I get the seat height baselined, lap the valve in with my very fine homemade checking paste to create a witness, and then bring the angles in to suit .... but everyone has their own particular process, swears by it ....... and at everyone else's

Stones can be incredibly accurate in the right hands, but are sloooow

[steve cowan]

I always use a bounce spring, and put light pressure to 'kiss' the seat and get back out fast .... you will have to do this several times to bring the seat or angles in

Not using a spring can be a recipe for disaster, and can get you into trouble fast .... especially when learning the ropes

Be careful with die grinder speed ..... depending on stone diameter speeds of 9000 - 12000 rpm for what you're doing is ballpark ...... die grinders can go 30k +

Most 'aftermarket' units are basically angle grinders with an adaptor, due to their entirely appropriate speed rating, if looking a little ungainly to use

Now the controversial bit :

I get the seat height baselined, lap the valve in with my very fine homemade checking paste to create a witness, and then bring the angles in to suit .... but everyone has their own particular process, swears by it ....... and at everyone else's

Stones can be incredibly accurate in the right hands, but are sloooow

thanks BC,
I don't think the controversial part is that at all,you have a style that works for you and probably for other people as well,thanks for sharing.
I figured stone went out of use in the 1980s and everyone had a seat and guide machine lol.
it is nice to see a lot of guys doing there own thing at home as a hobby as well and I fall into that category,looks like I can get plenty of advice here so thanks everyone.

[modok]

I quit lapping about 15 years ago.
IMO it is probably good for the seat, but not good for the valve.

I've seen many different finishing tools that can do a similar function without putting a groove in your valve.
There was a guy who made CBN abrasive coated valves for finishing cut seats for instance.

[BCjohnny]

I don't 'lap' the valve into the seat ...... not in the conventional sense most here would regard as, anyway ......

[Rimmo]

I take my hat off to you Steve, you don't do things by halves when it comes to working on your engines. I have to admire your dedication to your craft.

[SpeierRacingHeads]

If you want to lap it, use toothpaste.

Or dykem it up, put the valve in or stone, and spin it. If it's right, it will mark the seat.

[steve cowan]

I take my hat off to you Steve, you don't do things by halves when it comes to working on your engines. I have to admire your dedication to your craft.

Thanks Rimmo,
Its the speedtalk community that gives me inspiration

[steve cowan]

If you want to lap it, use toothpaste.

Or dykem it up, put the valve in or stone, and spin it. If it's right, it will mark the seat.

Chad,
Thanks for doing the video,very helpful and appreciated, the toothpaste trick is interesting will try that for sure.

[rebelrouser]

I want to see where the seat hits the valve. I sometimes use fine lapping compound just to see where it marks the valve. Stock engines I want in the center, performance I want a little to the outer edge. Many times you can simply take your hand and rap the valve sharply against the seat with your fingers a few times and it will leave a thin dark line where the valve is touching the seat.
And that leads into the question do you cut the job with or without an interference angle? I seldom use one, even though a lot of OEM's ask you to do it. My idea is that an interference angle takes a while to wear a seat in, and most performance engines I want to seal perfectly on fire up.

[allencr267]

Will low RPM pound out the high spots lapping makes to destroy a mirror perfect finish that'll cut/crush through the combustion leftovers, or does it need some thrashing?