Powered valve lapping tool

[Rannsachair]

Bu66er, I did find a few with poor reviews so chose the Katsu as folks on here have bought that brand.
Mrs Robo put an order in for one last night as she has a Prime account, at least Amazon returns are easy.

I thought the same, Ihave the Katsu dual action polisher and its lasted well for a few years now, though looks like the Chinese copies of the £40 Gunson are inferior. Sealey do one too at around £20, may be a safer bet?

 

[jsf55]

I had a Gunson one and wore it out i did so many heads with it, brilliant bit of kit !

 

[oldbikedavey]

I thought the same, Ihave the Katsu dual action polisher and its lasted well for a few years now, though looks like the Chinese copies of the £40 Gunson are inferior. Sealey do one too at around £20, may be a safer bet?

My two were made by Norbar, bought secondhand, and just bobble along happily.

 

[Melvyn Best]

I had one years ago ,possibly made by SPQR.? I didn’t use it much as I prefer lapping using a valve grinding stick . Must have done thousands of valves over the years. I also have a large tin of valve grinding paste that I “ borrowed “ off my dad around 68. A decent seat cutter and valve facing machine makes all the difference

 

[8ob]

There is always the argument that lapping doesn’t really work, being that the valve is raised on paste while grinding and when it’s wiped clean drops down a tad on unground parts of the valve and seat. In effect leaving a very thin valve/ seat contact ridge. Cutting/stoning seats and valves is a better way to go if you have the kit.

Bob

 

[minimutly]

There is always the argument that lapping doesn’t really work, being that the valve is raised on paste while grinding and when it’s wiped clean drops down a tad on unground parts of the valve and seat. In effect leaving a very thin valve/ seat contact ridge. Cutting/stoning seats and valves is a better way to go if you have the kit.

Bob

Well, if you cut the seat and either have a new valve or recut one, you should only need a tiny smear of fine paste, and after a couple of turns adding a drop of paraffin or heating oil gives as close as zero clearance as possible. Any mechanical means of lapping is just not needed imho.

 

[whm_fab]

Well, if you cut the seat and either have a new valve or recut one, you should only need a tiny smear of fine paste, and after a couple of turns adding a drop of paraffin or heating oil gives as close as zero clearance as possible. Any mechanical means of lapping is just not needed imho.

i was hoping someone would touch on this.

if the seats are cut properly, and valves are faced properly, there should be no need for the process of valve lapping at all. trying to recover a leaking /worn valve or seat through lapping will damage the shape of the seat that it will 'appear' as though it seals (when its cold because they've been worn into each other) but will leak like a sieve when operating as the valve and seat shape don't fit together anymore, one will be convex, one will be concave, or a combination of both.

the only caveat to that - usually the only time we lap valves on race engines is with a very fine diamond paste for a couple of seconds if there is a sign of very small chatter in the seat cutter, the lapping will flatten the microscopic ridges from the tool chatter on multiangle seat cutters.

a properly cut seat and valve should/will hold vacuum for over a minute without lapping

 

[Robotstar5]

I only want to do my old stationary engine valves so don't really need race spec tolerances as they only run at a few hundred rpm producing single figure hp.

 

[minimutly]

i was hoping someone would touch on this.

if the seats are cut properly, and valves are faced properly, there should be no need for the process of valve lapping at all. trying to recover a leaking /worn valve or seat through lapping will damage the shape of the seat that it will 'appear' as though it seals (when its cold because they've been worn into each other) but will leak like a sieve when operating as the valve and seat shape don't fit together anymore, one will be convex, one will be concave, or a combination of both.

the only caveat to that - usually the only time we lap valves on race engines is with a very fine diamond paste for a couple of seconds if there is a sign of very small chatter in the seat cutter, the lapping will flatten the microscopic ridges from the tool chatter on multiangle seat cutters.

a properly cut seat and valve should/will hold vacuum for over a minute without lapping

Well, ignoring stationary engines for a moment, I have some tweeks that allow valves to "relax" into seats, thereby improving sealing. However I've also been toying with heating heads on a bolted up torque plate, to try and replicate a running engine, given that the seat is at least likely to move in some direction. Carbon witness patterns on the back of race inlet valves sometimes show where leakage might be occuring, eliminating this leakage being the goal.

 

[OJCar]

 

[Seadog]

If only I could read it

 

[OJCar]

 

[Morris]

If only I could read it

 

[whm_fab]

I only want to do my old stationary engine valves so don't really need race spec tolerances as they only run at a few hundred rpm producing single figure hp.

ah, i missed that bit, a little ott so didnt realise it was was a put put put

 

[Seadog]

View attachment 523143

Have you tried to read the text?

 

[whm_fab]

Well, ignoring stationary engines for a moment, I have some tweeks that allow valves to "relax" into seats, thereby improving sealing. However I've also been toying with heating heads on a bolted up torque plate, to try and replicate a running engine, given that the seat is at least likely to move in some direction. Carbon witness patterns on the back of race inlet valves sometimes show where leakage might be occuring, eliminating this leakage being the goal.

im not sure thats going to be a worthwhile exercise tbh, how are you going to heat the valve red hot to 6-700c simultaneously in the head and make measurements?
there's no need to reinvent the wheel, just cut concentric, seats and valves, and the very same angle, and you dont need to worry about any of that, and valves 'relaxing' into seats, is honestly only a bad thing and gives me shivers

 

[Morris]

Have you tried to read the text?

Yes, I read it on my phone

 

[oldbikedavey]

View attachment 523129

Hackney's finest.....

 

[OJCar]

Have you tried to read the text?

Try it on a proper screen if your trying on your phone.
If you still can't read the text on a proper screen ...

 

[8ob]

I only want to do my old stationary engine valves so don't really need race spec tolerances as they only run at a few hundred rpm producing single figure hp.

Put the valves in a pistol drill and face them up with a house brick

Bob