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PostPosted: Mon Jun 18, 2012 8:52 pm 
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Are there any benefits of going over to a closed loop system from a open loop system ?


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PostPosted: Tue Jun 19, 2012 7:43 am 
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Slightly better mpg overall, but the closed loop thing is more about emissions really. A properly set up open loop system will touch similar figures. But a closed loop system will keep those figures more constant over time. It depends about what you want to do really. If you have no lambda or controller you will be into £250 in bits in all probibility. Over maybe an extra couple of MPG ?


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PostPosted: Tue Jun 19, 2012 2:54 pm 
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Ive always had hot weather starting issues, wondered if it would help with that.


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PostPosted: Tue Jun 19, 2012 4:00 pm 
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I doubt it. Most closed-loop controllers normally expect to start on petrol, and then switch to gas; so they don't provide many options for the starting conditions e.g. different priming for hot or cold.
Do you start on gas at present? Investigate your priming arrangements.

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PostPosted: Tue Jun 19, 2012 11:06 pm 
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If i start on gas from cold it takes a while to fire, due to the blos carb being further away than the normal type of carb/spacer ring im guessing. But it doesnt like starting on gas if the engine is hot and has been left a while. In this instance im never sure if it needs choke or not to start.


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PostPosted: Sat Jun 23, 2012 8:24 am 
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Froom what you describe, my guess is that you are still priming for a hot start, while in fact you will already have gas in the inlet - thus you get an over-rich mixture (similar to "flooding" in a petrol setup). Another option is that the reducer is allowing a small amount of gas to dribble through after you stop, and this builds up a rich mixture in the intake - but which will dissipate up the intake given a bit of time.

As an experiment, try stopping the engine by disconnecting the feed to the reducer solenoid - that will clear the inlet tract of gas. Then reconnect it and immediately do a hot start - but priming as though you were doing a normal cold start. I suspect you'll find it's near enough the same.

For a cold start, you are normally expecting an inlet tract that's more or less clear of air. I recognise the problem you have with a large volume between carb (mixer) and cylinders - my Rover V8 has a darn great plenum chamber on top of it ! So for a cold start, you dump a "slug" of gas into the intake which makes it rich. As you crank, this mixes with the clear air and hopefully you get something vaguely combustible.
If you don't prime, then you introduce gas at the normal rate, which initially mixes with air to make a too-weak-to-burn mixture. it takes a bit more cranking before you've cleared the air/weak mixture and the full strength mixture reaches the cylinders.

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PostPosted: Sun Jun 24, 2012 10:42 pm 
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Yes that makes sense, i think a lot of the problems ive had have been down to the old vaporizer. Since fitting the omvl 90 last week, it starts a lot easier even from cold. Not had a chance to check it in hot conditions as yet.


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