Grinding Valve Seats and Margins at Home?

[DirtyMech]

I'm replacing some intake valves in a cylinder head right now, and have found that,

big surprise, the new valves don't fully seal. I strongly suspect that the engine will

run like crap if I don't make these seats air-tight.

 

So I'm wondering if anyone here has succeeded in grinding their own valve seats and

margins at home? I understand that this is a high-precision operation that normally

requires accuracy within .001" and some very expensive machining tools.

 

Therefore my questiions is a two-parter:

 

1. Are there any shortcuts that would suffice for doing this job? I've imagined using squares

of snadpaper to put over the valve stems and grind the seats by rotating the valves in-place,

or using some low-cost drill bit attachments that are specifically made to grind the seats and

margins. So far I haven't been able to find any cheap tools or short-cuts like this.

 

2. I may have some money to invest in a proper valve griding machine. Does anyone recommend

a model or brand that goes for well under $10,000 new?

 

-------------------

 

Okay so that's my question. Now for general amusement, I'd like to share the at-home techniques I've used to detect the valve seal leakage:

 

1. Light Test: Put a small flashlght in the intake/exhaust ports in a dark room, and check if light shines through the valve seals.

 

2. Water Test: Put a garden hose in the intake/exhaust ports and check seals for water leakage with hose at full blast.

 

3. Air Test: Seal intake/exhaust port with lips (if possible) and blow into port to check for air-tightness. This is a bit harder to do than the others,

especially with heads that have fuel-injector ports, but it seems to be very effective.

[nipper]

er um

 

 

i am so afraid of you

 

"i wanted to save a little money" goes right up there with "here, hold my beer".

 

 

Not that i should encourage you, but you dont need an expensive machine to do the valve seats, but something more like this

 

http://cgi.ebay.com/ebaymotors/Kwik-Way-Willis-Jones-Valve-Grinding-Reamer-Tool-Sets_W0QQcmdZViewItemQQcategoryZ43991QQihZ019QQitemZ290249836552QQrdZ1QQsspagenameZWDVW

 

now if you have to grind the valves themselves you need a lathe, and an understanding of what the heck your doing.

 

nipper

[torxxx]

take the head to a machine shop and pay them to do it unless u plan on doing it for a living.

[screwbaru2]

I've done this a few times but not to Soobs. If the valves are new and the seats in the head are not burned or pitted you don't need to grind. Lapping the valve to the seat with lapping compound will do the trick. You want to see a narrow uniform "line" around the valve face and head seat. After putting the valves back together (spings installed) spray carb cleaner into the ports, if it doesn't leak out from around the valves after a few minutes you were sucessful! If not keep trying until they seal. Or take it to a machine shop and have a beer.

[DirtyMech]

er um

 

i am so afraid of you

 

"i wanted to save a little money" goes right up there with "here, hold my beer."

 

nipper

 

Ha ha yes nipper, I'm a novice with a tight budget. Thank you sooo much for going out of your way to discourage my attempt at a home repair job while pointing that out. While the initial ideas I threw out there might have seemed a bit naive (though the second one sounds very close to what's in that link you posted), I would've expected that kind of overtly disdainful remark from a dealership mechanic rather than a fellow USMB poster. And just to clarify, "I wanted to save a little money" (by doing the job at home) is one of the major reasons, if not The major reason, that this forum exists, no?

 

On a less sarcastic note, thank you sincerely for cluing me into the valve seat grinding tool. That's more or less exactly what I was hoping existed out there.

 

While, as you noted, I'm no automotive expert, I do understand from my 2000 Ed. of the GW Automotive Encyclopedia manual that the valve margins must extend 1/16" from the valve seats in all cylinder heads in order to ensure that the valves don't overheat. If the replacement valves are new and I have this tool, do you imagine I could meet this specification without the valve lathe?

 

If not, can anyone recommend a decent and affordable valve lathe?

[DirtyMech]

To Torxxx: Hell no. If I have to spend on special tools A HUNDED TIMES what I'd otherwise

have to pay a shop mechanic, then that's what I'll do. And yes, I'd like to be able to do

this for part of my living, and if not, at least for myself and my own stubborn curiosity.

 

To Screwbaru2: Awesome, that was exactly what I wanted to know. Thank you so much for cluing

me into Lapping Compound. Since I'm not hoping to make this car run forever, I'll try that first, though

I know I'll eventually be shelling out for the real tools. I'm still grateful for any suggestions on that

front if anyone highly reommends a particular tool.

[nipper]

http://www.chevyhiperformance.com/techarticles/89678_valve_angles/index.html

 

http://64.78.42.182/sweethaven/MechTech/Automotive01/default.asp?unNum=2&lesNum=4&modNum=4

 

Its technically not a hard thing to do, but i would find an old head to practice on.

 

I havent used a cutter, i've used stones, but here is a cutter

 

http://cgi.ebay.com/ebaymotors/NEWAY-VALVE-SEAT-CUTTERS-WOW-NO-RESERVE_W0QQcmdZViewItemQQcategoryZ35625QQihZ018QQitemZ280253089618QQrdZ1QQsspagenameZWDVW

 

 

nipper

[DirtyMech]

http://www.chevyhiperformance.com/techarticles/89678_valve_angles/index.html

 

http://64.78.42.182/sweethaven/MechTech/Automotive01/default.asp?unNum=2&lesNum=4&modNum=4

 

Its technically not a hard thing to do, but i would find an old head to practice on.

 

I havent used a cutter, i've used stones, but here is a cutter

 

http://cgi.ebay.com/ebaymotors/NEWAY-VALVE-SEAT-CUTTERS-WOW-NO-RESERVE_W0QQcmdZViewItemQQcategoryZ35625QQihZ018QQitemZ280253089618QQrdZ1QQsspagenameZWDVW

 

 

nipper

 

Awesome dude. I think I might actully try that first. Thank you!

[Reveeen]

I haven't used a cutter, I've used stones

 

Pretty well the same thing, when you use stones you must true them up all the time, a cutter is supposed to be harder than the valve seat (use cutting oil), never needs truing, and is far more suited to high volume production.

 

Lapping a "new" valve is perfectly acceptable, as long as you can get the seat to conform in short order, if you end up working the valve too much the contact area gets too wide, and you will be back inside in short order. The guides must be ok to lap the valve(s) successfully.

[DirtyMech]

I haven't used a cutter, I've used stones

 

Pretty well the same thing, when you use stones you must true them up all the time, a cutter is supposed to be harder than the valve seat (use cutting oil), never needs truing, and is far more suited to high volume production.

 

Lapping a "new" valve is perfectly acceptable, as long as you can get the seat to conform in short order, if you end up working the valve too much the contact area gets too wide, and you will be back inside in short order. The guides must be ok to lap the valve(s) successfully.

Cool, thanks for the expert advice Reveen! And thank you to everyone else who has offered advice. I measured how much the new valve's margins protrude from the old valve seats, and it appears to be almost exactly 1/16 of an inch. Therefore I feel confident attempting the valve lapping procedure first. Wish me luck!

 

On a side note, is that the Canadian (edit: Australian) magician Reveen that Ricky from Trailer Park Boys is mockingly nicknamed after? I was wondering how it was spelt; I could never find anything about him online!

[Reveeen]

http://en.wikipedia.org/wiki/Peter_Reveen

[WoodsWagon]

I got taught how to do valve work by an older guy who'd worked in ford dealers back in the 70's when they switched from leaded to unleaded, and they'd do valve jobs regularly.

 

Grinding the valves themselves is only to true the face up to the stem. New valve should be true, so no need to grind them.

 

Grinding the seats is to get the contact patch in the right area of the valve and to get it concentric to the guide. You use a post that fits tightly into the guide and use that to center the stones. You will need a 30 degree stone and probably a 46 degree stone. you want your main stone to be a degree off of what the valve face is so that they wedge. keep the stones cut straight with the diamond stone cutter tool. You pretty much drop the stones down on the center post that jammed in the guide and go to town with a 1/2 drill style thing and cut the seat till it's fresh the whole way round without pits. Then you take the valve and put it in the guide and smack it against the seat with your finger. A thin line will apear on the valve. You want the line in the valve face to be in the outer 1/3 of the contact area. When you lap the valve in, the contact patch will spread down the valve from this line. To adjust where the line is, you use the 30 degree stone to cut the face of the seat down.

 

It's crude, loud, and seems scary at first to take a grinder to the head, but it works. You need someone to take the time to show you how to do it.