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 Posted: Apr 8, 2017 11:30AM
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CA
Quote:
Originally Posted by jwakil
Quote:
Originally Posted by dklawson
You said "single nut you adjust from the bottom".  To me, that says you have an HS series carb, not an HIF.  At one time it was not uncommon for people to complain of engine stumbles and stalls in long sweeping turns due to the float swinging and closing off the fuel supply.

With the HS carbs the float bowl is a separate unit to the side of the main carb body.  The float bowl lid is held on by three screws in a symmetrical pattern.  Remove the float bowl lid and turn it so the float swings (more or less) front to rear instead of left to right.  Refit the lid.  Fit new fuel hose as necessary so you can reach from the hard fuel pipe to the fill nipple on the float lid.  

I do believe it is a float issue, and Dan's explanation makes sense.  Only reason I'm hesitating about reorienting the float is that it doesn't explain why it was fine before and I only recently started having this problem.  I'll open up the float bowl lid and look things over, as well as the damper. 
While you are at it, suck all the gas out of the fuel bowl to get any crud that may have settled into the tube leading to the main jet. And check the inlet jet (controlled by the float) is also clean.

.

"Hang on a minute lads....I've got a great idea."

 Posted: Apr 7, 2017 05:52AM
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Quote:
Originally Posted by dklawson
You said "single nut you adjust from the bottom".  To me, that says you have an HS series carb, not an HIF.  At one time it was not uncommon for people to complain of engine stumbles and stalls in long sweeping turns due to the float swinging and closing off the fuel supply.

With the HS carbs the float bowl is a separate unit to the side of the main carb body.  The float bowl lid is held on by three screws in a symmetrical pattern.  Remove the float bowl lid and turn it so the float swings (more or less) front to rear instead of left to right.  Refit the lid.  Fit new fuel hose as necessary so you can reach from the hard fuel pipe to the fill nipple on the float lid.  

I do believe it is a float issue, and Dan's explanation makes sense.  Only reason I'm hesitating about reorienting the float is that it doesn't explain why it was fine before and I only recently started having this problem.  I'll open up the float bowl lid and look things over, as well as the damper. 

1992 1275 SPI Mini

1981 Porsche 911 Turbo (930)

 Posted: Apr 6, 2017 10:48PM
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GB
Louis Walsh is a judge on the UK X-Factor, and was invovled with the group One Direction - as he is a "confirmed batchelor" you ought to be able to work the joke out.

 Posted: Apr 6, 2017 03:13PM
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Quote:
Originally Posted by Dan Moffet
I have no idea who Louis Walsh is or what's wrong with his willy. I'm guessing I probably don't want to know!

This somehow reminds me of the old Ted Kennedy/ChappaquiD*** joke.

His model Oldsmobile was recalled for steering wheel repairs because it could not make a turn when the owner had a woody.

 Posted: Apr 6, 2017 02:10PM
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CA
Quote:
Originally Posted by Alex

Remove your air filter and elbow, fire up the engine, and watch the damper with a mirror as you rev the engine.

It drops like a stone as soon as the throttle is closed because the damper only works in one direction (like Louis Walsh's willy).

Alex: I will sit corrected and accept your explanation. I also forgot about the dashpot spring! My dashpot (indeed the whole Mini) has not moved in about a year and a half (due to health challenges) so I won't be able to do as you suggest. But spring is coming, snow is melting and we're getting heavy rains this week that should was the salt off the roads. Then I will wake her gently.

I have no idea who Louis Walsh is or what's wrong with his willy. I'm guessing I probably don't want to know!
Cheers!

.

"Hang on a minute lads....I've got a great idea."

 Posted: Apr 6, 2017 07:54AM
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GB

Remove your air filter and elbow, fire up the engine, and watch the damper with a mirror as you rev the engine.

It drops like a stone as soon as the throttle is closed because the damper only works in one direction (like Louis Walsh's willy).

 Posted: Apr 6, 2017 07:49AM
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CA
Yes it should for various throttle settings, except when he suddenly lifts of the throttle. Since it has a damper, it will take at least a little time for the dashpot to descend. The delayed rise is what provides the accelerator pump effect - momentary richness. A delayed fall would give the opposite effect.  

.

"Hang on a minute lads....I've got a great idea."

 Posted: Apr 6, 2017 06:40AM
 Edited:  Apr 6, 2017 07:48AM
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GB
Air velocity should remain pretty much static across the jet regardless of throttle opening - that's the whole point of a variable venturi carb like the SU...

Edit:  Have a read of this:  https://en.wikipedia.org/wiki/SU_Carburettor  

 Posted: Apr 6, 2017 05:20AM
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CA
Quote:
Originally Posted by Alex
When was the last time you changed the waxstat ?

Dan, if there wasn't enough 'draft' over the bridge with the throttle closed, the engine wouldn't run on tickover - and the fuel level in the float chamber has nothing to do with that.
It could if the fuel level was low but not too low. Idle mixture could have been adjusted to compensate for the low float level. When the throttle is closed there is high manifold vacuum and slight carb throat vacuum, but the dashpot would be almost all the way down. Even with low flow through the carb, the air velocity across the bridge would still be relatively high - enough to draw fuel (as it does to get the accelerator pump effect).  However, when in a left hand curve, the HS bowl would slosh away from the main jet, lowering the level in the main jet. Since he's just lifted his foot off the throttle, the dashpot would still be up, allowing more air across the bridge but with the throttle closing or closed  the velocity through between the dashpot and the bridge would drop very low, resulting in starvation.
In other words, at idle, the fuel level in the jet might be somewhere around half instead of nearer the top, but when he corners the level in the jet drops to the point of starvation.

I hadn't thought about the Waxstat, but if it failed, doesn't it fail "rich"?

.

"Hang on a minute lads....I've got a great idea."

 Posted: Apr 6, 2017 02:26AM
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GB
When was the last time you changed the waxstat ?

Dan, if there wasn't enough 'draft' over the bridge with the throttle closed, the engine wouldn't run on tickover - and the fuel level in the float chamber has nothing to do with that.

 Posted: Apr 5, 2017 12:58PM
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CA
He says it "If I give it some gas, it stays on..." That wouldn't suggest a coil problem to me.
It may be as simple as low float - with the throttle closed, there isn't enough draft across the jet to draw fuel, resulting in lean-out. But with some throttle maintained, the dashpot would stay up a little, providing good venturi draft on the main jet.

.

"Hang on a minute lads....I've got a great idea."

 Posted: Apr 5, 2017 07:08AM
 Edited:  Apr 5, 2017 02:18PM
mur
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Reply removed. 

 Posted: Apr 5, 2017 06:10AM
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US
You said "single nut you adjust from the bottom".  To me, that says you have an HS series carb, not an HIF.  At one time it was not uncommon for people to complain of engine stumbles and stalls in long sweeping turns due to the float swinging and closing off the fuel supply.

With the HS carbs the float bowl is a separate unit to the side of the main carb body.  The float bowl lid is held on by three screws in a symmetrical pattern.  Remove the float bowl lid and turn it so the float swings (more or less) front to rear instead of left to right.  Refit the lid.  Fit new fuel hose as necessary so you can reach from the hard fuel pipe to the fill nipple on the float lid.  

Doug L.
 Posted: Apr 5, 2017 05:53AM
 Edited:  Apr 5, 2017 05:56AM
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Recently I've noticed my 82 Mini idle drops and sometimes dies when I'm making a hard left turn with my foot off the gas.  If I give it some gas then it stays on.  Doesn't seem to happen when making a right turn.  It has the stock SU single carb, (with the nut you twist at the bottom of the jet to adjust fuel ratio ).  Otherwise the car runs fine and I haven't messed with the fuel ratio or idle setting for quite a while.

1992 1275 SPI Mini

1981 Porsche 911 Turbo (930)