Valve lapping tool

I have just spoken to my engineer who is doing my cyc. Head.
A problem has arisen with his lapping tool that he has nothing which will fit his machine.
This can't be the first time and it won't be the last, can somebody shed light how this should be correctly done.
For my 850 I have nominal diameters for the
Inlet: 28.573 mm
Exhaust: 31.76 mm
Is the diameter taken from new valves in new guides for the rotating dorn?
In this case: 7.912/7.886 mm

If somebody has any pictures they would greatly interest me.

John in distress

The dia is the diameter of the valve head, the valve stem dia does not come into the mix.

You need Neway valve seat cutters.



There are tungsten blades set in blade holders that work as hand cutters and work really well, the pilot needs to be sized to fit the guide, I have 2 pilots, 5/16 and 5/16 - 1 thou. There are 3 angles in the kit I use.

Uncountable valves have been lapped with the old-fashioned hand operated, suction cup tool and valve lap compound. The only thing that matters is getting a good seal. The engine will not know the difference between a good seal accomplished with the 5 dollar hand tool or the high-tech machine. The machine is, of course, faster

Oops, sorry...You are talking about cutting valve seats; I misunderstood, thought you were asking about lapping valves.

I have a lapping attachment for the electric drill - it was made by Gunson and is ancient.

I have just checked online, and amazingly you can still buy them.



It has worked brilliantly for years!

Kommando that looks just fine. What did the Neway kit cost or what does it cost now and where is it available.

It could be an option than getting a fitment made for his machine for 200 €.

I bought direct from Neway many years ago and the kit with the 3 angles was £120 but would be more now and no way to get it past customs anymore.

This is their German agent

GERMANY​

OKO SATURN WERKSTATT-TECHNIK GMBH & CO.​

Nurtingen-Reudern
Phone: 49 (0) 7022 60256 0
Fax: 49 (0)7022 60256 10
info@saturn-tools.de
www.oko-saturn.de



As the valve stem diameter is very close to certain VW valve sizes I am surprised he is not already got tools that can be used even with adaption.

The sizes the Neway heads say they will cover is conservative, you can move the blades out further than they say and still cut well. The blades are solid and thick with no deflection.

We seemed to have confused valve lapping with seat cutting!

They ain't the same, as the two vastly different tools pictured testifies.

Gforce has answered the question as asked, the rest of you seem to have answered the question the OP meant to ask!