Morris Minor Owners Club

I recently bought a 12G940 head on ebay, and I've just noticed that it has double valve springs. Is this standard fitment? It will be totally unnecessary for me to have uprated springs on a 1098cc, so I will probably change them if they're non standard!

The doubles were only fitted as standard to the larger inlet valve versions of the 940 head. As the 1098 MUST NOT be revved over 6000, just remove the inner springs......

I haven't got my spring compressor and I hadn't realized the springs were separate. If I have the big valve head, will I have enough valve clearance on a 1098? I know they sometimes require countersinking - is there a way to do this myself?

Measure the valve head diameter. The larger valve version is better saved/used on a 1275 engine. It's the exhaust valve (same size all 940 heads) that may need recessing..... Measure the gap! You need 320thou. It's detailed in many many threads.

Just use a valve seat cutter if you need to sink the valves.[frame][/frame]
Measure it up carefully.[frame][/frame]
Regards
Declan

Ok that looks easy enough... now just to find a correctly sized valve seat cutter!
Do you also have to measure from the top deck of the block to the top of the piston at tdc, or is this generally flush?
Is 40thou to much to attampt with lots of lapping compound and a pillar drill?

Fortunately for me it looks like I do have the small valve head (inlets are 33mm variety). Now I just need the space to clean and inspect the head!

You should really, really , go through the earlier posts! It is quite likely that there is enough clearance and you will not have to do anything at all!
Most people seem to get away as-is.
Personally, I would advocate assembling the top end with a good (Payen) 1275 head gasket, but with zero exhaust valve clearance. CAREFULLY turn the engine over on the handle until an exhaust valve is fully open. Using a suitable lever, check that there is still movement before the valve head touches the block top face. Thus, when set with .015" valve clearance, you will have your safety margin.
I did all the maths on my set-up, seriously and repeatedly, with a dial gauge and surface plate. This indicated that my clearance was borderline, yet when all was bolted down there was plenty of clearance! I come from an engineering background, but still believe in real situations over a page of figures any day!

PS: The piston top face doesn't come into the calculations as it is always below the top face of the block (unless someone has "blueprinted" the engine-you should be so lucky!)

PPS: If you do need to remove any amount of material with lapping paste it will take forever and you will end up with weird shaped valve seats! Lapping paste is just for removing/trueing slight imperfections!

PPPS: get a spring compressor, ditch the inner valve springs, and lightly lap the valves just because you don't know what the state of the seat is! At the same time, a little work with a dremel in the exhaust throat area will only be a good thing!

As above - well described LA! Can use plasticine as a depth gauge during the trial assembly... Valve hitting the pistons is not the issue - it's clearance from the block that IS the issue. 320 thou from top face of valve to head face is essential to avoid any damage. Gasket thickness and valve gap (15 thou) is the safety margin.....