Hasse
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| posted on 2/7/04 at 06:45 AM |
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Advice on X-flow please!
After 3.5 years of building, I have finaly got the car on the street for a test drive.
(All GRP-work remaining).
But.... the engine is running terrible.
It´s a standard 1600 X-flow from -79 with no tuning at all.
It starts ok with a bit of choke but the idling is very unstable and hesitates a lot when picking up rev.
There´s a lot of missfiring and carburator-flashes.
When "idling" on 6-7-800 rpm it suddenly goes up to about 1500 for a few seconds, and then fall back again.
When checking ignition with a stobe-lamp, it seems to be about right.
(about 12 deg before TDC, but moves with the unstable idling)
All electrical ignition parts new except for the coil.
Cant find any air leaks into the intake.
Have tried to clean the carb. The accelerator pump seems to be ok.
Any suggestions are welcome.
Thanks in advance.
/Hasse
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David Jenkins
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| posted on 2/7/04 at 07:14 AM |
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Hasse,
The first obvious thing to look at is the firing order - have you got the plug leads in the right place? The X-flow has an odd order - 1,2,4,3 with
anticlockwise rotation.
Apart from that, do you have the right coil fitted? The reason I ask is that I had exactly the same symptoms as you, because I had a coil designed for
electronic ignition rather than the correct one for points. The wrong coil gave me a weak spark that would only just run the engine.
Also look at the condition of the distributor cap, plug leads, rotor, and so on. Another cause could be trying to run a 12 volt through a ballast
resistor.
Do you have a Colortune? (or know someone who has?) - that gave me the clue that my spark was weak.
good luck !
David
[Edited on 2/7/04 by David Jenkins]
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muller
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| posted on 2/7/04 at 07:46 AM |
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Hasse
When I bought my Locost the car had stood for the best part of a year. It had great trouble starting and showed the same symptons as yours (erratic
idle, flashing back thru the carb etc)
Once I took the car for a proper long drive most of the problems disappeared.
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britishtrident
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| posted on 2/7/04 at 10:28 AM |
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The sudden increase in revs is called "hunting" its is causd by weak mixture and or over advanced ignition.
It could be the ecommy/anti-stall diaphram in the carb need renewed a known problem on Ford Webrs. however first .
(1) Clean the jets & check for water in float chamber.
(2) Check points gap on each lobe of distributer cam -- make sure you are using correct gap for distributer type).. For a Ford/Fomoco/Autolite
distributer this 23 to 27 thou -- always set new points in this type of distributer at 27 thou as the gap will close up with initiasl running.
(3) Check mechanical centrafugal advance is free and working
(4) Check ignition timing
(5) Check condition of plugs
Only then set idle mixtures and idle speed. Start with mixture screw(s) 2 turns out from the weakest setting (screw in to weaken out to make
richer)
A colour tune plug used in each cylinder in turn will help get an initial mixture setting but is useless for emmision purposes.
[Edited on 2/7/04 by britishtrident]
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britishtrident
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| posted on 2/7/04 at 10:37 AM |
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forgot to add
If all else fails check valve clearances then do compression test.
[Edited on 2/7/04 by britishtrident]
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Hasse
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| posted on 5/7/04 at 06:13 AM |
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Thank´s for your proposals!
I have´nt got it sorted yet, but with some more time I hope I will.
/Hasse
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lotustwincam
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| posted on 27/7/04 at 09:42 PM |
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Hasse,
If you are using the standard Motorcraft distributor, check the bearings for side play.
You might think that the points gap is set correctly, but with worn bearings the timing will be all over the place, causing the engine speed to hunt.
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Mark Allanson
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| posted on 27/7/04 at 09:53 PM |
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I does sound like weak mixture, how did you check for air leaks? I have a doctors stethoscope with a length of brake pipe in the end, it will detect
even the smallest leak (I also use it at work for dry testing for water leaks with compressed air)
If you suspect worn dizzy shaft, just put a strobe on it and look for the jumping timing marks
If you can keep you head, whilst all others around you are losing theirs, you are not fully aware of the situation
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