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 single choke carb setup 
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Firing on two.

Joined: December 28th, 2008, 9:11 pm
Posts: 388
Post single choke carb setup
I've put new gaskets and given the carb a clean, but I stupidly didn't remember how the choke eccentric goes on. Have I put this together correctly? I couldn't make head nor tail of the haynes pictures...

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October 25th, 2011, 11:59 am
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Agony Aunt - You have a car problem? Speak to Ken

Joined: March 6th, 2009, 1:40 am
Posts: 3675
Post Re: single choke carb setup
Ben,
the fast idle cam looks OK, however the clip holding the throttle rod to the lever isn't correctly engaged... ;)

That carburettor has got the lever for the throttle closing damper fitted.
Do you have a centrifugal clutch on the car?

ken

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October 25th, 2011, 1:49 pm
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Firing on two.

Joined: December 28th, 2008, 9:11 pm
Posts: 388
Post Re: single choke carb setup
thanks ken, no - no centrifugal clutch (that I know about.... ) how might I tell?

The thing that made me think something was up was that the idle speed screw doesn't sit against anything, unless screwed right the way in.


October 25th, 2011, 2:05 pm
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Firing on two.

Joined: December 28th, 2008, 9:11 pm
Posts: 388
Post Re: single choke carb setup
clearly, the easiest way to determine if it's got a centrifugal clutch is to jam it into first without touching the clutch :lol:

Can someone tell me where the idle jet is on this carb?

<edit> no problem, I've found this page and learnt how to refer to the parts in French at the same time:

http://eric2chman.free.fr/page19.html

la vis de richesse - how much more elegant is that than 'the mixture control screw'


October 26th, 2011, 10:00 am
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Firing on two.

Joined: December 28th, 2008, 9:11 pm
Posts: 388
Post Re: single choke carb setup
Had to try and turn the car around today, so five litres into the tank and spin icon the starter. Eventually petrol came through and the car started nicely. I left it running on my drive for five mins and then pushed the choke home. Idle was a little quick, so I twiddled the stop on the carb. All sounds good so far!

However, I then left it idling and about five mins later it started to miss and stalled. I restarted it but noticed that pushing the throttle tended to make it nearly stall. Then, it stopped and refused to start completely. Does this indicate that the idle mixture is too rich? I bet if I went out now, 5 hours later, it would startup straight away.

What's the best way to set the idle mixture on a single choke carb?

Thanks! Ben


January 28th, 2012, 10:20 pm
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Firing on two.
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Joined: December 9th, 2008, 7:50 pm
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Post Re: single choke carb setup
meshking wrote:
I restarted it but noticed that pushing the throttle tended to make it nearly stall. Then, it stopped and refused to start completely. Does this indicate that the idle mixture is too rich?


Unless there was petrol pissing out everywhere I'd suggest it was actually very lean. That's the same symptom you get when you're running out of petrol! I'd be tempted to whip the top off and see if there's anything in the float bowl. Could be a dodgy float valve or something further up the system...


January 29th, 2012, 12:49 am
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Firing on two.

Joined: December 28th, 2008, 9:11 pm
Posts: 388
Post Re: single choke carb setup
Thanks Luke. I'll check the float height and try to find the mixture control screw, which doesn't appear to be where the website above indicates.


January 29th, 2012, 1:06 pm
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Firing on two.
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Joined: August 19th, 2010, 10:44 pm
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Post Re: single choke carb setup
Luv the red knob :lol:

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January 29th, 2012, 1:19 pm
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Joined: April 18th, 2009, 11:43 am
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Post Re: single choke carb setup
May I suggest an engine service first. If valves and timing is out, you have no hope of adjusting the carburetor.

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January 29th, 2012, 1:21 pm
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Agony Aunt - You have a car problem? Speak to Ken

Joined: March 6th, 2009, 1:40 am
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Post Re: single choke carb setup
Ben,
is the accelerator pump working correctly?
If it isn't, the engine will tend to stall as the throttle is opened quickly.

No need to have the engine running, remove the rubber hose between the carburettor and air filter, then check as to whether or not there's a good jet of petrol from the small brass tube pointing down into the carb throat as the throttle is opened quickly.
If there isn't any, you'll need to check the accelerator pump diaphragm, its spring and the adjustmet of the pump's stroke.

Does your carburettor have an 'air volume control screw'? If not, the only real difference is that you have to make all idle speed adjustments using the throttle stop screw.
Other than that, idle mixture is always adjusted via that screw facing backwards towards the starter motor.
Some had a plastic knob, some were a slotted screw with an external spring and some were hidden inside the casting.

The usual procedure should be followed, warm the engine up, weaken mixture until the tickover falters, then richen it until the tickover is steady, which is usually about a half turn...

ken.
( Is the coil OK? Best not to let the symptoms of a dodgy coil muddy the waters. ;) )



meshking wrote:
Had to try and turn the car around today, so five litres into the tank and spin icon the starter. Eventually petrol came through and the car started nicely. I left it running on my drive for five mins and then pushed the choke home. Idle was a little quick, so I twiddled the stop on the carb. All sounds good so far!

However, I then left it idling and about five mins later it started to miss and stalled. I restarted it but noticed that pushing the throttle tended to make it nearly stall. Then, it stopped and refused to start completely. Does this indicate that the idle mixture is too rich? I bet if I went out now, 5 hours later, it would startup straight away.

What's the best way to set the idle mixture on a single choke carb?

Thanks! Ben

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January 29th, 2012, 3:45 pm
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