Valve seat recessing

[silloyd]

So, I'm heading down the 12g940 route and have what appears to be a perfectly good head but the exhaust valves are all sitting at about 280 thou, so too close to the face of the head.

I've looked at valve seat cutters but the Neway ones are ludicrously expensive.

As alternatives I've looked at the following:[frame][/frame]
Described as a Black & Decker / Wolf valve seat grinder wheel

or[frame][/frame]
Described as a Cobalt Countersink Drill Bit

Anybody got any views if either would do the job and if so which would be best please?

[Alec]

Hello Silloyd,

you will need a machine to run the first, probably around 10 to 15,000 rpm and with a mandrel that fits the valve guide, the second looks as though it is only 16.5 mm diameter (from the base of the spindle) so will be too small? A larger diameter will probably do the job as long as it is used in a pillar drill to keep it vertical. Just be sure it is a 45 degree angle, which the one in the picture is.

Alec

[horrace]

i have done the same with a 12g940 but i got my local machine shop to do it, they charged me £4 a valve plus vat, and that was for them to sink the valve to 320 with a 2 face grinding process so they sink the valve and then champfer back the shielding created by the extra sinking. for £20 it was a no brainer for me.............

[bmcecosse]

Mine were done with a 45 degree countersink held in a pillar drill - with a small square of emery paper in the countersink - top tip from the tool maker to prevent chatter. Obviously it must be 45 degrees - and large enough diameter to reach the whole seat. Each valve seat was centred under the countersink and the pillar drill run slowly with light pressure to cut the seat. The stop on the pillar drill was pre-set to the correct depth so all seats ended up the same depth. The head was restrained so it couldn't spin -but not clamped down so the cutter could self centre. The whole job took 10 minutes during a lunch break! The seats were lovely smooth grey colour and only needed the lightest of grinding in with fine paste.

[MarkyB]

I wouldn't try doing it free hand, my seat cutter has a bit that fits inside the guide to keep it centralised.
Could you hire one?

[silloyd]

Thanks for all the replies.

Looks like the grinding wheel is a non-starter. The Cobalt drill I'm looking at is 31mm diameter, so just wide enough, with 45 degree angle cutting edges and I do have access to a pillar drill.

That said, I am nervous about trashing the head, so I'll probably look into finding a local machine shop to do it at a reasonable price first.

Thanks again.

[MarkyB]

Have you asked at your local branch? Someone there may lend you one or do the job for you, it doesn't take long once the head is off and the valve out.

[Declan_Burns]

I used a valve seat cutter with the correct pilot. I think it was from Sykes Pickavant.They show up on ebay every now and again.[frame][/frame][frame][/frame]
Regards
Declan

[silloyd]

Had a quick chat with bloke in the garage what services SWOTBO's motor (and MOT's the Morris) and he said "I'm sure I've got a set of those cutters somewhere, haven't used them in years, cost me about £300, you can borrow it if you want..."

He did then try to persuade me to have hardened seats put in so that I could use it with unleaded....!

So, for a small (liquid) thank you I now have a solution in the form of a perfect Neway cutter, pilot and handle.

[Declan_Burns]

A depth gauge as shown in my photo above is quite handy. The 2mm aluminium angle fits over the cumbustion chamber and the depth gauge measures the distance through the hole to the valve+2mm. Here a better view how it works. Such a gauge is a very handy tool indeed and nowadays you can buy digital ones very cheap from Aldi. The usually have them once or twice a year for about a fiver (at least here).
Regards
Declan[frame][/frame][frame][/frame]

[silloyd]

Declan,

Thanks for the tip on the aluminium angle.

I do have a digital vernier (picked up of eBay for £7), which has the advantage of reading in mm/inches and the ability to zero at any point and take relative readings, so it will allow me to accommodate the thickness of the aluminium accurately.

[MarkyB]

Top result!
Treat his tools with the utmost respect and return them promptly, preferably clean and lightly oiled.
Don't be tempted to speed things up by using hand tools in a power drill.