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graham
United Kingdom
10 Posts |
 Posted - 07 Feb 2011 : 22:06:55
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Hi, My 111A has a flat spot just as you start to open the throttle. Adjusting and balancing the carbs has helped a little, but it's still there. It's a bit dangerous, as it can "die" as you pull out at a junction if you don't give it enough revs(although I'm used to it now). I have checked the points/plugs/timing.
I'm thinking air may be being sucked in to the mixture where it shouldn't, so I am going to take the carbs off and check the manifold gasget, and perhaps have the carbs re-built somewhere.
One thing I considered, if it is air being sucked in, can't you smear grease over (possible leaky) joints and see if a temporary fix occurs ?
There is no particular reason for this post, just musing. But if anyone has any thoughts they would like to share, I'd love to hear them.
I don't want to take the carbs off, if I am barking up the wrong tree !
Graham. |
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1922
United Kingdom
549 Posts |
Posted - 08 Feb 2011 : 18:27:41
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I'm not familiar with your carbs.
If it was a weber I'd say your accelerator pumps not working or progression holes/drillways blocked. Usually solved by a good clean but can be a broken spring.
For a stromberg it might be the piston lifts too easily - maybe the damper is broken or empty.
Sounds like running lean - I had similar symptoms when the inlet manifold came loose on the fastback (may years ago when I was running on twin Strombergs). Ran fine on the open road, ticked over ok, but was a real b*gger to drive around town.
I've got a Gunsons 'colortune' which is useful for diagnosing this sort of problem. It's a spark plug that you can see through - you can see what colour the flame is inside the combustion chamber and get an idea whether the car is running rich or lean.
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janmarine3
South Africa
286 Posts |
Posted - 08 Feb 2011 : 21:44:08
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Spray some quick start around the inlet manifold, carb bases and shafts - if there are leaks it will definately effect the running of the engine. Sometimres one can pinpoint a specific place where you have air leaks.
Also check in the engine bay when it is dark , have the engine running, the darker the better, to see or hear if you have any unwanted spark losses anywhere.
Cheers
Jan. |
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graham
United Kingdom
10 Posts |
Posted - 12 Jul 2011 : 22:08:25
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Hi Jan and 1922,
Thanks for your advice. I didn't have any success with a rebuild kit, so I sent carbs to Carburetter Exchange and they rebuilt them. Everything is fine now. They said that accelorater pumps seemed to have been deliberately blocked at some time but there was sufficient leakage past the blockages to fool me that they were OK !So you were right 1922:-) !
Graham. |
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1922
United Kingdom
549 Posts |
Posted - 13 Jul 2011 : 18:56:09
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Excellent - very pleased that we helped.
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twin zenith re-build
