valve grinding

[grainger]

hi

im still here messing with my moggy (1098 1970 traveller) its been getting more sick all year, misfiring, oily plug (number 2), lack of power

anyway, i finally summoned up enough courage to take the engine apart, and yes i had a badly chipped exhaust valve and the valve stem oil seals had disintegrated.

there is also a build up of stony stuff on a couple of valves and in the exhaust port on number 4... is this the petrol additives ?

so ive got a new valve and cleaned it all up and ive started grinding the valves in. i was advised to use an electric drill rather than doing it by hand, but it doesnt seem to be doing the trick. after almost damaging the first one by tightening the chuck on the stem i decided to put a bit of plastic pipe on them, but its very difficult to get enough pull on it, and all this high speed spinning cant be doing the valve guides much good. i was thinking id prefer to do it by hand, does anyone know where i could get the proper suction tool from ? and a tub of grinding paste ?

cheers
grainger

[Willie]

I would imagine that any car accessories shop would sell the
tool and the double ended grinding paste tins. remember that
the exhaust valves need a good wide seating whereas the inlet
valves need only a thin complete ring of ground area.

[grainger]

cheers willie but i havent been able to find any in the shops round here. i just wondered if there was a decent supplier on the net. i borrowed a tin of paste but i dont want to give it him back empty, i thought id better buy my own !!

so the exhaust valve seating should be wider than the inlet, i will remember that. should the valves sit flush in the combustion chamber or do they usually stick out a little ?

thanks for the help

grainger

[Alec]

Hello Grainger,
the drill suggestion is not a good one, valve lapping requires a to and fro movement. You can buy a tool that uses an electric drill and replicates the traditionall back and forward movement. Assuming you find a rubber sucker stick, and some paste you will probably need to start with a coarse grade. Put some on the valve and add a drop or two of thin oil on the seat and into the guide and start lapping. You will find after a few turns that nothing seems to be happening, add some more paste and continue for a short while. The sound it makes tells you if it is cutting or not. Wipe both the valve and the seat and look at the colour, any low areas will be black and ground areas a matt grey. The valves usually will not be bad but the seats will tend to have lots of black spots indicating low areas. If you do not have a complete circle on the seat you either have a lot of lapping or else take the head to an engine repair specialist and have him re-cut the seats. Ideally the face of the valves will be proud of the combustion chamber, if not it means the seat is recessed and the valve will not flow as well.

Alec

[grainger]

thanks alec

yes i felt like i might end up doing more harm than good with the drill, i dont mind doing it by hand if i can find one of the sticks. ive been searching through the kids old toys for a plastic sucker dart or something such like, but they are all too grown up now !!

the valve that ive replaced is the only one with a badly pitted seat, i can see where the carbon is, i dont think its so bad to need recutting.

anyone have any idea about the white stony stuff in the ports and on the stem of one or two valves ? .. its incredibly tough to chip away.

cheers
grainger

[Alec]

Hello Grainger,
I'm fortunate in having a wire wheel on my electric grindstone and that makes short work of any such build up. You could try putting the valve in your drill and use coarse production paper (I think Hafords sell it), it is white in colour, you want 45 grit. Once the build up is gone you could use 180 or about wet and dry to finish off. Th ports are harde, so buy a wire brush that fits an electric drill, most accessory shops or engineers merchants sell them.

Alec

[Cam]

For a valve grinding stick try your local motor factors. There are LOADS round here. Motormania do them. Not sure about the paste though (I have a couple of double ended tins still).

Look for the small 'Arkwrights' type motor factors. I'm sure they would sell them.

Oh and an angle grinder with a twisted wire cup brush makes short work of the 'stoney white/brown' buildup on valves. Or just fit a new one, they are not expensive.