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It happened - zero compression on cylinders 1 & 2

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John Gervais:
It looks like I might have gotten off easy!

I can't feel any burn through on the block face and can still see the milling marks between the chambers on the head.  There wasn't any coolant in the cylinders, either.  My back is killing me right now, but if it feels ok tomorrow, I'll clean everything up and hopefully put it back together.

I can barely see any of the cylinder hone's cross-hatch marks, so this one's apparently getting a bit tired, so I will need to rebuild the spare block at some point sooner than later.

I wonder why it burned through the gasket like that?

What I assume is #1 piston is suspiciously clean and also appears to have some pitting. These are typically symtoms of lean mixture and detonation. I thought your spark plug pictures looked like lean running (one man's opinion), I usually like to see brown to dark brown. They didn't seem extremely lean but I would always like the mixture to be a little rich rather than a little lean. Worse fuel mileage, more power and less chance of detonation.


John Gervais:
I just noticed that myself - I'll wipe the top with some solvent and take a look with my glasses on and a magnifying glass to be sure if they're pits or only towel dust from wiping the oil from the surface, and maybe back off the timing a tad and give it a little bit more fuel.  It's an Aldon Yellow dizzy, now with 2000 or so miles on it.  But I think that this head gasket will only be a band-aid - I think I need to build a new one.

I drive primarily on the highway, and my last trip (160 miles) averaged to 33mpg.  Generally, I'm getting between 31 and 34 mpg, measured over the past 5 or 6 months, and each highway drive is a minimum of 45 minutes over 4000 rpm at highway trot, usually between 70 - 80mph.

I was able to get a somewhat better picture of the plugs after I'd limped to the parking lot and shut it down.  Not that they show what it was doing when I lost compression...

Be sure you check that head carefully to make sure it's flat.....

John Gervais:
I will - it's one of Calver's, so I don't want anything bad to happen to it.

Are you using a precision-milled bar and feeler gauges to check yours?

I just found out that Hyacinth has a conference on Wednesday, so I'll have access to her car; if necessary I can take it to the MG racing shop and check it properly, and possibly leave it with them with my box of components (new valves, guides, seals etc.) to have it re-surface skimmed and rebuilt if necessary. 


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