Valve seat re-cutting vs replacement (1 Viewer)

[cps432]

I posted this thread in the 60 forum, but I’ve had no response. I thought I would try here before taking a blind plunge.

From my original post:

I’m overhauling my engine right now (1987 2F from an FJ60) and I’m at the point of doing the valve job. I have new guides and valves along with a reamer and lapping tool.

I’m not taking it to a machinist because it’s a 4 hour drive one way and I’ve done all the work myself up to this point.

My question for you engine gurus is this: If I replace my valve seats will I also need to have a cutter tool to fine tune them or will the new seats be ready to lap with my new valves right off the bat?

I’m wondering if it’s better to get a neway cutter tool and salvage my existing seats. They aren’t in great shape, but they aren’t beyond re-cutting either.

If I go the route of replacing them do you have any tips or tricks for getting the old ones out? I’m very skilled with a dremel/ die grinder and was thinking I’d cut some relief slots and pry them out. I have a press for installing new ones.

Any other advice on doing your first valve job?

 

[B y r o n]

The questions you are asking is why you take the time and spend the money to have a shop do the work. Valves done improperly will leak and/or burn. Heaven forbid you undersize the guide and get a valve to seize in the head. Not to mention if any of the surfaces need to be straightened or leveled. I'd say contact the shop and see if they can fit you in where you only have to do an over-niter. In the long run it will result in a better result and be money well spent.

 

[cps432]

The questions you are asking is why you take the time and spend the money to have a shop do the work. Valves done improperly will leak and/or burn. Heaven forbid you undersize the guide and get a valve to seize in the head. Not to mention if any of the surfaces need to be straightened or leveled. I'd say contact the shop and see if they can fit you in where you only have to do an over-niter. In the long run it will result in a better result and be money well spent.

I completely understand your point, however, I am a long way from the shop and I don’t have a vehicle I can use to make that trip.

 

[snaggletto]

I have 'notes' from a cruiser guru that generally recommended keeping the valve seats and opening them up for larger stainless steel small block Chevy valves (1.5" and 1.84") along with new valve guides. Sounds like you are staying with stock valves, either way, I would definitely clean up the seats you have rather than trying to remove and replace the valve seats.

 

[cps432]

I have 'notes' from a cruiser guru that generally recommended keeping the valve seats and opening them up for larger stainless steel small block Chevy valves (1.5" and 1.84") along with new valve guides. Sounds like you are staying with stock valves, either way, I would definitely clean up the seats you have rather than trying to remove and replace the valve seats.

I’ve heard of using Chevy valves in a 2F. Hadn’t considered it. Yes, I am keeping it as stock as possible. I’m not looking to make it a high performance engine or anything of the sort. I just need to make it run so I can get to and from work and go camping etc.

 

[Malleus]

As long as there's metal there, you're better off using it than replacing the seats. There's little danger of damaging the head installing them, but getting them out, on a bench in your garage, is another thing entirely.

If you keep the seats and can replace the valves with STD size, the seats should be recut, at least kissed, before lapping to ensure a good fit. Lapping only removes a frog hair thickness and a kiss with a cutter will flatten everything out, in preparation for the lap.

You might be able to get away without the cutter, but you might also spend 4 hours lapping and find out that 1) you're out of lapping compound , and 2) your seats don't fit.

I was taught to use a Coke bottle (the glass kind; the mouth is round and will seal on a good seat - fill the bottle half full of water and place the mouth on the seat) to check the seat fit. This way you can check one valve at a time, instead of filling the while head with water and looking for leaks.

 

[cps432]

As long as there's metal there, you're better off using it than replacing the seats. There's little danger of damaging the head installing them, but getting them out, on a bench in your garage, is another thing entirely.

If you keep the seats and can replace the valves with STD size, the seats should be recut, at least kissed, before lapping to ensure a good fit. Lapping only removes a frog hair thickness and a kiss with a cutter will flatten everything out, in preparation for the lap.

You might be able to get away without the cutter, but you might also spend 4 hours lapping and find out that 1) you're out of lapping compound , and 2) your seats don't fit.

I was taught to use a Coke bottle (the glass kind; the mouth is round and will seal on a good seat - fill the bottle half full of water and place the mouth on the seat) to check the seat fit. This way you can check one valve at a time, instead of filling the while head with water and looking for leaks.

That’s the kind of thing I was hoping to hear! The intake seats have a bit of pitting and the 3 angles have kinda become a rounded surface, but from my untrained eye they look to be salvageable.

I’ll go ahead and get a cutter tool and give them a kiss.

I’m a professional fine woodworker and I’m very detail oriented and skilled at creeping up on tolerances. I feel I can manage this on my own. If people can rebuild these engines in sub Saharan Africa in a shed with a dirt floor I assume I can do it in my heated garage. If I screw it up I’ll take the steps needed to correct it. I do it all day long at work.

 

[rkymtnflyfisher]

There's no shop in Belgrade or Bozeman that can make this happen? Who is 4 hours away?


Or are you not in Bozo?

 

[middlecalf]

Is that seat in the last pic (right one) have a chunk missing?

 

[cps432]

Is that seat in the last pic (right one) have a chunk missing?

Looks like it, but no. It’s carbon. I have it all cleaned up since those pictures.

 

[3_puppies]

There's no shop in Belgrade or Bozeman that can make this happen? Who is 4 hours away?


Or are you not in Bozo?

X2 there is a good shop in Three Forks, unless they just do diesel engines, that is what we used them for.
good engine shop in Helena also.

I thought Jim C had a write up about using the chevy valves and stainless seats in a 2F head
@FJ40Jim

 

[peesalot]

IMO those are not bad at all, it looks like a single angle seat, just need to lap the new valves in, lap first that way you can see if one needs to be cut.

 

[aztoyman]

Send a PM to @toyotaboy80. He is an engine machinist.

 

[toyotaboy80]

Engine machine work is really a case of you can only do it as good as your tools allow you to. Your expectations of the quality of work will dictate what tools you need.

Lapping a valve in is really old school and takes a lot of life out of the valve and seat face. A lapped valve doesnt seal as nice as a properly cut or ground seat. By the time you spend 4 hours lapping a valve into a worn out seat, you wont have flat surfaces and most likely will have widened the seat too much and changed the position of the seat on the valve.

99.9% of the time changing the guide will change the valves position relative to the seat. 99.9% of the time the seat needs to be cut to restore the center. And 99.9% of the time the change is too much to lap a valve into it.

Your intake seats will take a cut no problem. One of your pictured exhaust seats looks pretty hammered out, there may not be enough material left to restore the seat width and position.

A properly done valve job is so precise that zero lapping is required.

New seats are blank seats that require them to be cut or ground to final position. If the seat isnt the exact same dimensions as the one removed, seat pocket machining will be required. There are a couple ways to remove a seat... one is to cut it out with a pocket cutter until youre within a few thousandths and the seat can be peeled out not disturbing the pocket. The other is using a tig torch to go around the seat a couple times and the seat will shrink and you can pull it out. Installing the seat is best done with a piloted install die and hammer it in good and hard. You want minimum .005" interference on the seat to pocket or you risk dropping a seat when the head gets hot. Hammering in a new seat often times will disturb the seat concentricity of the one beside it. Always install seats before machining the one beside it.

As simple as cylinder heads are, they really require accurate tooling and skills to make them last for any appreciable amount of time.

Chances are the deck surface on any 1987 head is way off "flat".....aka needs to be resurfaced.

Can you freight your cylinder head to a machine shop?

 

[cruisermatt]

It’s so refreshing to learn a bunch of things in a single thread reply.

 

[cps432]

Engine machine work is really a case of you can only do it as good as your tools allow you to. Your expectations of the quality of work will dictate what tools you need.

Lapping a valve in is really old school and takes a lot of life out of the valve and seat face. A lapped valve doesnt seal as nice as a properly cut or ground seat. By the time you spend 4 hours lapping a valve into a worn out seat, you wont have flat surfaces and most likely will have widened the seat too much and changed the position of the seat on the valve.

99.9% of the time changing the guide will change the valves position relative to the seat. 99.9% of the time the seat needs to be cut to restore the center. And 99.9% of the time the change is too much to lap a valve into it.

Your intake seats will take a cut no problem. One of your pictured exhaust seats looks pretty hammered out, there may not be enough material left to restore the seat width and position.

A properly done valve job is so precise that zero lapping is required.

New seats are blank seats that require them to be cut or ground to final position. If the seat isnt the exact same dimensions as the one removed, seat pocket machining will be required. There are a couple ways to remove a seat... one is to cut it out with a pocket cutter until youre within a few thousandths and the seat can be peeled out not disturbing the pocket. The other is using a tig torch to go around the seat a couple times and the seat will shrink and you can pull it out. Installing the seat is best done with a piloted install die and hammer it in good and hard. You want minimum .005" interference on the seat to pocket or you risk dropping a seat when the head gets hot. Hammering in a new seat often times will disturb the seat concentricity of the one beside it. Always install seats before machining the one beside it.

As simple as cylinder heads are, they really require accurate tooling and skills to make them last for any appreciable amount of time.

Chances are the deck surface on any 1987 head is way off "flat".....aka needs to be resurfaced.

Can you freight your cylinder head to a machine shop?

This is awesome information! Thank you for taking the time to explain that much.

I could possibly freight the thing to a shop or take some time off work to make the drive if I can rent a truck for the trip. I am on a budget, but I also need to get this done so I can move forward.

@3_puppies, I did see the shop in Three Forks, but I think they only work on Diesel engines. There’s a shop in Belgrade but they’ve been booked up for a while and I’m not sure if they have the machines to do it or if they outsource this kind of thing anyway.

I’ve done all my own work on this truck and I’ve been learning so much. I kind of just wanted to learn to do a valve job on my own, but I’m thinking it might behoove me to leave it to the pros. Maybe I’ll get a carbide cutter tool and try it myself by hand. If I don’t have success I can always have someone else fix it.

The head is just barely out of spec around the 4-5 cylinders. Everything else is very flat.

 

[3_puppies]

the shop in Helena has done several for me in the last few years, he is an old school guy.
He's usually only 2-3 weeks out for my projects.

has the head been checked for cracks? that would be first before anything else.

 

[peesalot]

Toyotaboy80 has a point regarding if the seat needs to be cut, the cutting moves valve down and it can get too low so as the lip of valve hits surface around seat, thats when a new seat is needed. Lapping is like running a gear pattern for a diff, you can see what the contact rings looks like and if it is thin in spots.

 

[rkymtnflyfisher]

There is a Toyota shop in Missoula that may have some experience.

There is also an engine shop in Hamilton, but now we're at that 3 plus hour drive mark.

 

[middlecalf]

It’s so refreshing to learn a bunch of things in a single thread reply.

Man, I didn’t even know the valve seats were replaceable like the valve stem guides (U and Z), I thought they were just ground into the head block . (I‘m thinking F, not 2F). Don’t see anything about seats in the parts book.