Valve grinding

[millerman]

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Is this valve grinding good enough or does more time need to be spent twirling the suction pad

[bmcecosse]

The two exhaust seats still need a bit more..... to remove all traces of 'pits'. TBH - I use a leccy drill for the basic grinding....then just finish off by hand with the fine paste. Some suggest they should be finished with Brasso/Tcut...but frankly I think that's beyond all reason! Are the guides new? They look a little bit 'oval' - but that may be a camera lens effect.

[beero]

Put the valves and springs back on, put the head on it's side and pour some paraffin in the ports.
If none leaks then it's good to go.

[IslipMinor]

Millerman,

More grinding I'm afraid! There should be no marks on either the valve or the seat - there are witness marks on either/both.

I also use an electric drill. It is two speed and variable, so only use quite slow revs. Put the head on its side, ideally held in something like a 'Workmate' to hold it securely. Use plenty of fine paste (I have never needed to use coarse) and some oil on the valve stem. Tighten the chuck on the valve stem and pull/push the valve on and off the seat with only a few seconds of actual lapping time - if you hold the valve against the seat for any real time, it will squeeze the paste out and you will then have a dry valve to seat contact, which does nothing for good lapping.

After a minute or so, take the valve out, clean off paste and oil and repeat the process until fully lapped in. Usually needs no more than a few minutes for each valve.

[les]

I thought valve grinding was done by revolving the valve in alternate directions. Well that's how I was taught !

[bmcecosse]

That's because your wrists don't rotate..... You can switch the leccy drill back and forth if you wish....

[millerman]

Thanks all for replies.

Will give the job more time and use a drill as Richard's advice

[bmcecosse]

Are the guides good ? Pointless exercise if there is wear in the guides...

[mike.perry]

I thought that using a leccy drill was cheating, obviously it is common practice. I have one of those valve lapping things that fit in the drill.
If you have unleaded hardened valves and seats don't even think about trying to lap them in

[les]

It's all these new kids on the block Mike!

[millerman]

I thought that using a leccy drill was cheating, obviously it is common practice. I have one of those valve lapping things that fit in the drill.
If you have unleaded hardened valves and seats don't even think about trying to lap them in

How good are those "valve lapping things"? I remember them being advertised.

Wouldn't borrowing one to see how it goes but bit of a trip done the M4...............

[bmcecosse]

I remember the 'valve lapping tool' from years back....never had one.. If you have 'unleaded' seats and valves = they won't ever NEED lapping - if they are the real deal.....

[mike.perry]

The labels have long disappeared but I think it was SPQR or something. It is plastic orange, one end goes in the drill chuck and the other has a sucker on the end which is supposed to stick to the valve head. You hold the plastic bit in the middle and the valve end oscillates. It is a bit awkward on a side valve head as the head studs can get in the way. I will try a photo tomorrow

[bmcecosse]

This is the beast.... http://www.ebay.co.uk/itm/22-28mm-Valve ... 2a310ec37f