cylinder head: odd valve appearance?

Side valve, 803, 948, 1098., 1275 and Vizard mods
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jcrcleeman
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cylinder head: odd valve appearance?

Post by jcrcleeman »

As I hope you can see from the attached photos 1 valve is totally different to the other 7 in its appearance.

It looks like when a spark plug goes when the fuel mixture is weaker and gets that light mushroom colour, but the other 7 look very dark and are "crusty" .How is this possible?

The head was very low on compression in no. 2/3 cylinders (75!) and evidence of gasket failure is evident on the head. Image But why the valve oddity?

Any suggestions/ideas are very welcome as usual.

John.
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philthehill
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Re: cylinder head: odd valve appearance?

Post by philthehill »

I would suggest that the colour of the valve (exhaust) in question is about right and the other valves are not right.
The other valves are crusty because of oil either coming down the valve guides or coming up past the rings.
The exhaust valve in question appears to be very pocketed/sunk into the head.
The land between No:2 and No:3 cylinder does not look to be good. The head face may benefit from a light skim.



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Custard
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Re: cylinder head: odd valve appearance?

Post by Custard »

What state is the top of the pistons in?

If you wind them to the top do they wobble around a lot?

Sean.



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jcrcleeman
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Re: cylinder head: odd valve appearance?

Post by jcrcleeman »

Thanks for those observations.

I'm actually fitting a fully reconditioned head (another 12G202) so hopefully if the valve guide's are the problem that will be solved.

I've not got access to the car again till Tuesday evening so I can't comment directly on the possibility of "wobbly" pistons, although when I wiped the piston tops to check the stamped details they didn't seem unduly sloppy. What degree of "wobble" are we looking for?

I've attached a cleaned piston photo, they were nothing like as bad as the head ports ( that's just clean oil on the pistons and bores by the way), also a couple of the skimmed refurbed head I'm going to fit....with an old style Mr Grumpy copper gasket set to 44ftlb torque (as per bmcecosse recommendations).

Am I doing this right?
John
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Custard
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Re: cylinder head: odd valve appearance?

Post by Custard »

I usually check the lip on the bore and I haven't an exact measure.

If they don't look unduly bad just put the head on and compression check after the valves have been set.

That's always good policy on your own car as you then have a baseline to compare it with for any future tests down the line.

I don't think there is anything different about a Mr Grumpy gasket to any other copper gasket and I wouldn't presume to possess enough knowledge to contradict the late BMCEcosse.

Sean.



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