Topic: Should I replace these valves?

[bahia]

I let one of my exhaust valves sit in an ultrasonic bath of Berryman's for a couple hours, and this is what they looked like afterwards.
I'm not sure if this is rust, or discolored carbon deposit. It definitely has a brown appearance to it.
Do I let it soak more? The rest of the exhaust valves looked to be about the same.
Intakes were not as bad, but haven't run them through the ultrasonic yet.

[spotty]

just my thinking but are the deposits proud of the surface or pitted below the surface ?

if they're above the surface you may well be able to cut them off whilst grinding the valves back into the seats, especially if they're just carbon, rust might be harder to move as it could well pull pits out of the surface as you grind them back

if the 'deposits ' are actually pitting below the surface you're probably best off getting new valves as the amount of work required to get the pits cut down as well as the amount of metal you'd lose would leave the heads of the valves way too thin to be safe to use

what condition are the valve seats in ? if the valves are that sh1tty they may well have hammered the seats to death

and have you tried some gentle wire wheel action on one to see what it does ?

[The Lone Builder]

Take a bit of emery paper to it; if it’s carbon, it’ll come off.

[robvangulik]

Clamp the valve in a power drill and turn it clean with a screwdriver. Only takes a minute.

[Bodi]

I would clean them with a wire wheel then try valve grinding compound and see if I get a good polished ring at the seat. If so, I think they would be good to go. There is some discussion about whether these valves can be reground (on a valve grinder) as the Stellite surface hardening is quite thin, and if you grind through it the valves will wear quickly.

[754]

Blast ,or otherwise get em clean, grind them see what you got..
 Btw do you know which valve went where ?
 If not then you really need the top line.

[bahia]

Thanks everyone!
I think it's more ultrasonic time, and wire wheel if necessary.

just my thinking but are the deposits proud of the surface or pitted below the surface ?
what condition are the valve seats in ? if the valves are that sh1tty they may well have hammered the seats to death
and have you tried some gentle wire wheel action on one to see what it does ?

The deposits are definitely proud of the surface. That's a good observation. I sure that can rule out the rust I feared.
I think I'm gonna give them some more time in the ultrasonic, and then hit them with the wire wheel if they're still looking nasty.

The seats just look like normal carbon deposit (see pic).
I'm dropping them off for vapor blasting tomorrow. I'm thinking those will clean up nicely.

Clamp the valve in a power drill and turn it clean with a screwdriver. Only takes a minute.

I've heard some frown on this, as it can damage the valves.
But, I'm not a machinist... so just something I heard.

Btw do you know which valve went where ?
 If not then you really need the top line.

Yes, I'm keeping track. I wasn't sure, but figured valves are one of those machined elements that marry with its partner.

[754]

That seat is looking bad, , it has to get ground.. 

[bahia]

That seat is looking bad, , it has to get ground..

Is that the same as lapping? Or something else?
I was planning on lapping.

[754]

Way beyond lapping... which is a slight touchup..
 Needs to be machined.. aka valve grind..

[bahia]

Way beyond lapping... which is a slight touchup..
 Needs to be machined.. aka valve grind..

Just got the head and cylinders back from vapor blasting. With all that carbon off now, still think they need to be ground?

[spotty]

they've come back looking real pretty, probably wouldn't hurt to get the lapping compound out and give them a spin just to check

[newday777]

Way beyond lapping... which is a slight touchup..
 Needs to be machined.. aka valve grind..

Just got the head and cylinders back from vapor blasting. With all that carbon off now, still think they need to be ground?

Much better! Even...A horse of a different color!

[newday777]

Did you end up replacing the valves?

[pjlogue]

At a minimum I would lap each valve/seat to check your contact width.  The valves you show look to have a wide contact area which isn't good.  It is hard to tell from the photos though.  The seats look pitted too.  While the engine is out and apart it makes sense to do the job right.  If the pits are deep or the contact margin too wide, the seats will need to be recut and the valves refaced.  Getting new valves and having the seats recut would be what I would do.. 

-P.

[754]

Ypou have had over a week to play with it, how did you make out ?
I do hope you realize  that eventually components wear out and need a rebuild. Not uncommon after 40 years.
 Also a good valve job these days , will probably out perform , what this motor had when it was brand new..

[PeWe]

Checked guides if too worn?

Put a valve into it, let it lift 10mm. Wiggle the valve holding the disc. It should not move sideways.
If not repaired, ex guides are most likely in need of replacement. Probably valves too.

If lucky, in guides might be OK. If just a little play, replace. Seats are cut after guide replacement so do not lap valves before guides are checked.

This might be a situation where valves/guides  are not worn enough to take it apart for a restore. But too worn to assembly if already taken apart.

[MRieck]

As Per said.....check the guides. I am sure they are loose. That exhaust seat is shot.....it needs a valve job. Not worth doing a valve job with lose guides. Personally I'd replace the guides and valves and get a fresh valve job.

[RAFster122s]

MRieck is an expert, he does this for a living. You can bank on what he is telling you.

[MRieck]

Thanks for the compliment.....I appreciate it. The head also has to be milled......you can see the corrosion in the fire ring area. The CB550 intake guides are still available and can be used on the exhaust side.....the cost is very reasonable. You will also need 8 orings that fit onto the guides. The only valves I know of are the Kibblewhite and those are a bit pricey but less than the OEM exhaust valves which are still listed as available.