De-Coke needed?

[M25VAN]

Finally got some pics of my coked up head.

RH chamber (No.1) the carbon was well above the valve bases

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Next pic shows RH chamber (No.3) with the space between the valve heads and chamber wall at 4-5 o'clock gone.
You may just spot in the LH chamber (No.4) the reason for the head removal .

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[bmcecosse]

Hahahaha - you could probably have cleared the 'coke' with some water injection - but the Holy valve does need head off... Be sure to use 15 thou gap on the exhausts - and check/reset every 3000 miles. Valves only burn when the gap closes up!

[M25VAN]

Hahahaha - you could probably have cleared the 'coke' with some water injection

I don't think the neighbours washing would have liked that, it was sheets day.

Valves only burn when the gap closes up!

Is that the likely cause of the problem? I've had a valve go like this in the past, just a bigger hole.
Wish I had checked the gap before I took the head off now although it had been ok on previous checks. I'll see how much wear is in the valves/guides when I "pop" them out.
One thing I will say is the new gasket went on without any hylomar this time. I've not had a leak when I've used it in the past but I forgot how much cleaning up it took to get it off. Half a day bent over the engine bay did my back no good at all.

[MorrisMinor-65-1000]

Hahahaha - you could probably have cleared the 'coke' with some water injection

Water injection is something I've always wanted to try but never got round to. I rebuilt my Rover engine a few years ago and cover a reasonable motorway mileage. I had the head off last year to change the little end bearings and it had picked up a fair amount of coke by then (big carbs running a touch rich for performance) so the time may come to decoke again in a year or two. How much practical experience do you/anyone have of water injection? There's a lot of scaremongering on the internet about bending con rods and such like, but it strikes me that as long as you get the ratio right, it should be very effective. How do you do it? Spray bottle to spray a mist into the carbs at meduim revs?
Any insight gladly received.

Cheers

[bmcecosse]

Yes - you could do it that way - or just suck water in via the vacuum advance pipe. Good hot engine, decent revs - and probably best out in the country well away from clean sheets........ And no need for Hylomar or any other bodger goo! A wipe with grease is all you need.... n the valve gap may only disappear when the engine is hot - enough to start the valve (and seat!) burn....

[IslipMinor]

Please see the pictures below to see the effect of an unintended introduction of water into No.4 cylinder - both the piston crown and head chamber are spotless! It works!

For the gory details of what happened please see the post 'A Real Puzzler'
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