JamesyCottony
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| posted on 15/4/16 at 08:10 PM |
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quote:
Originally posted by rusty nuts
I was taught to clean SU piston and dash pot with brake fluid 50 years ago, it still works and is cheaper than carb cleaner. Clearances between
pistons and dash pots are critical and as BT points out never use any abrasives.
You guys reckon I have ruined the carb then?
It wasn't an all over harsh sand, it was just to get the muck off the surface with 2500 paper
[Edited on 15/4/16 by JamesyCottony]
[Edited on 15/4/16 by JamesyCottony]
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mark chandler
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| posted on 15/4/16 at 09:54 PM |
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You will not have done it any favours, but not all may be lost.
Anyway, depending on the carb it may have a lifting pin on the underside which raises the piston slightly when pushed, little rod, Spring and circlip
if not use a screwdriver to lift the piston 1/4" when idling.
If the revs increase it is running to rich so back out the mixture screw, to weak and the revs will drop, set correctly and the revs may rise slightly
or stay the same.
If it stalls or does not Rev cleanly when you crack open the throttle the oil in the dashpot is to thin so try a heavier grade.
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JamesyCottony
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| posted on 16/4/16 at 12:04 AM |
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quote:
Originally posted by mark chandler
You will not have done it any favours, but not all may be lost.
Anyway, depending on the carb it may have a lifting pin on the underside which raises the piston slightly when pushed, little rod, Spring and circlip
if not use a screwdriver to lift the piston 1/4" when idling.
If the revs increase it is running to rich so back out the mixture screw, to weak and the revs will drop, set correctly and the revs may rise slightly
or stay the same.
If it stalls or does not Rev cleanly when you crack open the throttle the oil in the dashpot is to thin so try a heavier grade.
How much do I fill the dashpot? Also surely not much damage was done as it still runs? And when I Rev it (after it dies then picks up) it sounds
really nice
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cliftyhanger
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| posted on 16/4/16 at 05:02 AM |
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Have you topped the damper oil up? (20/50 oil best, thinner oil reduces the enrichment, thicker increases it)
Lead additives don't contain lead (ok, a couple do but hard to find, even if they are still available) most contain a brew of other stuff that
hopefully does the same job as lead, but do your research as to which ones work. There was some proper lab tests a few years ago, IIRC the castrol one
was OK. And another which I can't remember. Most others did nothing very much.
But as I said, these cars will run for years with no issues as the seats harden up with lead memory from when leaded fuel was about. Our mini has been
with us for several years, never used additives. Head off recently, no recession at all and no sign of unleaded seats either.
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JamesyCottony
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| posted on 16/4/16 at 06:03 AM |
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How much oil goes in the dashpot and where does it go? In the small hole and to the top?
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ian locostzx9rc2
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| posted on 16/4/16 at 06:31 AM |
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The oil to the dash pot going in the top unscrew the cap on the top of the carb you only need a tiny bit of oil in it 20/50 is best but 10/40 will
work ok .is it idling now if so make sure it hasn't got any air leaks around the carb and inlet manifold spray carb cleaner/ wd40 around the
area if the revs change you may have an air leak ,also worth putting the area you live as I'm sure there would be someone locally on here that
could take a look .
[Edited on 16/4/16 by ian locostzx9rc2]
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JamesyCottony
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| posted on 16/4/16 at 06:48 AM |
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quote:
Originally posted by ian locostzx9rc2
The oil to the dash pot going in the top unscrew the cap on the top of the carb you only need a tiny bit of oil in it 20/50 is best but 10/40 will
work ok .is it idling now if so make sure it hasn't got any air leaks around the carb and inlet manifold spray carb cleaner/ wd40 around the
area if the revs change you may have an air leak ,also worth putting the area you live as I'm sure there would be someone locally on here that
could take a look .
[Edited on 16/4/16 by ian locostzx9rc2]
I live near Chichester 
I put some 20W50 in the dashpot and had to put my hand over the inlet to start it again.... and idle was rough and it kept on dying. I then (while it
was running) adjusted the mixture and the revs raised, it became smoother and when i put throttle on its revs nicely and draws air in nicely, seem to
be pretty sweet.
It got to temperature, the fan then kicked in 
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ian locostzx9rc2
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| posted on 16/4/16 at 07:33 AM |
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Glad you have got it running
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JamesyCottony
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| posted on 16/4/16 at 09:46 AM |
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I have noticed like a light brown sludge stuff coming into the coolant tank, would this just be old sludge that has built up due to lack of running?
It's not sitting on the top, oil on dipstick looks nice
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mark chandler
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| posted on 16/4/16 at 09:55 AM |
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Probably just rubbish coming through, skim it off.
SU's are very clever devices, much underrated.
Once warmed up do as I suggested above, air filter off you can see the piston sitting just off its seat with engine vacumn, using a flat bladed screw
driver insert in the gap between the body and piston and gently twist to lift the piston by 1/4" and if set correctly the revs may rise slightly
or stay the same.
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JamesyCottony
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| posted on 16/4/16 at 10:04 AM |
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quote:
Originally posted by mark chandler
Probably just rubbish coming through, skim it off.
SU's are very clever devices, much underrated.
Once warmed up do as I suggested above, air filter off you can see the piston sitting just off its seat with engine vacumn, using a flat bladed screw
driver insert in the gap between the body and piston and gently twist to lift the piston by 1/4" and if set correctly the revs may rise slightly
or stay the same.
When the engine was spluttering the revs didn't move at all when I did what you suggested. Will try later on when I get home
Thankyou everyone for your help so far
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britishtrident
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| posted on 16/4/16 at 02:06 PM |
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10w/40 oil as 20w/50 causes problems in winter weather
Autotrans oil also works
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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