Hi all,
Well I guess I'll be poking around tonight removing the sump first as it's
the easiest, trying to look down the spark plug holes (sorry no boroscope -
oh btw I can spell 'Titanic' <G>) etc. The spark plugs were all nice and
brown on the tip but a couple of them had some oil around the base, tiny
bit. Absolutely no sign of damage on the plugs. Someone mentioned a bit of
carbon could have dislodged from the top of the piston and thats what I'm
hearing, I'm afraid I'm not game to try breaking it up with the rev test!
Knowing my luck as it's running at the moment, I'll punch a hole in the
block!!
I really, really hope it wasn't my carb settings that caused this - Barney
my timing was on spec (at least over the last 6 months) - 20 degrees BTDC at
1000rpm, vacumn removed. I think one of the reasons why my timing was weird
yesterday was because the car was not fully warmed up and idling well (?).
It was running at it's normal temp - mine always sits 3/4s between Cold and
Normal and only gets to normal when it's idling on a really really hot day
or I'm giving it heaps. It doesn't overheat - new water pump, hoses,
radiator recore etc, doesn't lose a drop of water.
I feel sure it wasn't overly lean, mainly because it seemed to me, and I
have NO experience at this but when it was lean while I was tuning it, the
exhaust had a *really* distinctive splashing sound to it, when enrichening
the mixture the splashing went away to a steady beat - sounded great, the
note altered again to offbeat - no splashing with a black exhaust when I
went too rich - just like the manual says it should. Maybe the thing wasn't
used to getting so much good mixture into it as it used to have the biased,
lean needles, leaky carbs, leaky air pump botched manifold etc and this
extra power was too much for the rings/piston or whatever's broke. Am I
dreaming? <G> I don't know. You tell me, but I felt a distinct 'whoaa baby'
push in the back after my final alterations and a *sob* minute or so later
'Titanic' impression by the engine! <G>
Let y'all know what I find. Thank you very much everyone for your help,
valuable experience, and kind words. Feel better to know I'm not the only
one who's been through this! I guess you have to make some mistakes to learn
from them.
One last question - is it ok for me to just fix the one piston with the
problem? I was wanting to drive the car till end January when I was going to
rebuild the motor completely for racing. Can I get away with just fixing one
piston, new head gasket, rings etc?
Cheers,
Neil.
--
Neil Cotty - Sydney, Australia
1970 MG B GT / 1959 MG A 1600 Mk1
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