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impco 200 adjustment 

 

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 Post subject: impco 200 adjustment
Posted: Fri Apr 27, 2012 12:54 am 
Oompa Loompa
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Location: renmark
SA, Australia

hi, does any body know how to adjust the impco 200 mixer ?
there is 3 adjustments , one screw with a spring around it , a brass screw with a hole and a notch cut in the top and where the delivery hose from the converter goes to the mixer there is a adjuster there ..

anybody help ?

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 Post subject: Re: impco 200 adjustment
Posted: Tue May 01, 2012 10:36 am 
Getting Side Ways
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 Post subject: Re: impco 200 adjustment
Posted: Sun May 06, 2012 1:44 am 
Oompa Loompa
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Location: melbourne
VIC, Australia

There are only two main adjustments.
The screw with the spring is idle mixture.
Its an air bleed screw so in is rich en and out is leaner.
The power valve on the vapour inlet is for wide open throttle mixture. This should only be set on a dyno or with a good air/ fuel ratio meter connected the the vehicles exhaust.
Go too lean and you will burn valves very quickly as combustion temps, on gas, will rise dramatically when too lean a mixture or A/F ratio is run. Gas already burns hotter than petrol, run it too lean and combustion temps become so high that the exhaust valve cannot dissipate the excess heat and will begin to burn, or melt, or weld to the seat.
Lean power mixtures are the main cause of LPG engines burning valves.
A N/A LPG engine should never be run leaner than a 12 to 14 : 1 air fuel ratio.
Air fuel ratios above this will rise exponentially with leaner fuel ratio. Anything past 15.5 to 1 will almost guarantee shortened valve life. Even though most N/A LPG engines will still make good power at 15 :1 + and feel fine to drive, it will shorten engine life dramatically.
Scary part is the majority of aftermarket LPG systems fitted to 6 and 8 cyl cars in aus do run far too lean at wide open throttle (WOT). This is mainly due to cheap, undersized systems being fitted to unaware customers cars. Most of the cheap LPG systems available in Aus are designed for 4 cyl and small 6 cyl engines. They simply have inadequate flow to suit our big Aussie sixes.

But rest assured your Impco system with a 200 mixer should adequately fuel a Falcon 6, when set right.
If you haven't got a air fuel ratio meter I would suggest you get a dyno run carried out and set it at the 12 : 1 mark. You'll find the engine makes its peak HP at that mixture (or close to) as well.
Then once its set right its pretty much forget, provided you keep the engine well tuned and the converter in good shape.

Idle is easily set if you have a EFI vehicle with a oxy sensor in the exhaust.
Simply use a multimeter to check O2 signal output. 0v is a lean mixture. .45v is perfect fuel mixture, (or Lambda) and 1v is rich. (most old O2 sensors will only produce a max of .8 or .9v)
Make sure the O2 sensor is warm by holding revs at 2000 for a min or so the allow to idle while monitoring voltage with a multimeter. (make sure the earth of the meter is to a good engine earth)
Screw idle screw OUT until reading dips just below .45V.. then slowly wind screw in until a just rich reading (or above.45v is reached) that will get idle mixture pretty close to ideal.
NOTE if your car runs a LPG computer or processor you will have a different tuning method as the processor will normal be closed loop (or cycle mixtures constantly from rich to lean) at idle.
In this case its best to do it by ear, and find where the engine idles sweetest, whilst still allowing the mixtures to cycle from rich to lean.
If you have an LPG processor fitted to your system and you don't see closed loop operation at idle and cruise you have a problem and will require further investigation of the system. A non cycling (or open loop) operation will increase your fuel economy, (usually) and not allow the system to work as designed, also engine emissions will be higher.

Hope this helps a bit. I tried to explain it as simply as I could, but realised I have rambled on a bit.

There are many many factors that influence fuel ratio in aftermarket LPG systems. And inexperienced tuning can be a minefield. But a well tuned and maintained system, such as the Impco system you have, will give many years of trouble free, reliable service and excellent power (because Impco air valve mixers typically flow better than a restrictive mixer ring system) with adequate fuel mixture at wide open throttle applications to provide acceptable combustion temps..therefore longer exhaust valve and seat life.
Cheers.[quote][/quote]

 

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 Post subject: Re: impco 200 adjustment
Posted: Mon May 07, 2012 9:10 pm 
Getting Side Ways
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blownba wrote:
(because Impco air valve mixers typically flow better than a restrictive mixer ring system)


Got any flow testing to back that up?

 

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 Post subject: Re: impco 200 adjustment
Posted: Wed May 09, 2012 1:27 am 
Oompa Loompa
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Location: melbourne
VIC, Australia

Ha Ha.
Do I really need to.
You can believe what you want with that statement.
How bout you show some data to back up your claims on here?? That would be more interesting...
How long have you been fitting and tuning LPG??

 

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 Post subject: Re: impco 200 adjustment
Posted: Wed May 09, 2012 7:37 pm 
Getting Side Ways
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Yeah good one.
Thing is my friend, I've seen the test results and Impco them selves provide the flow data for them.
To say the least, your info is misleading at best.

A 200 mixer will flow no better then a 40mm ring mixer. It's well known the 225 is better suited to the 4L falcon engine, it's just a little more work to make them fit neatly.

Impcos own information show the 200 is way under sized for a 4L engine with max engine speed of 5000rpm. According to Impco it's suited to a 4L engine with a max engine speed of only 3800rpm

How long have you been misleading people?


Sorry just noticed your from Vic. that tells me enough. I'll ignore any thing you have to say from now on.

 

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