Impco 200 Tuning

[Jimbo]

I just bought a wideband and decided to hook it up to the gq (LPG)

Once warmed up it idles around 11:1 (cant get it lower with idle screw) and driving around and cruising on light throttle its around 13:1

When you accelerate it shoots up to 15.3:1 and the same for cuising at 80km/hr +

Seems like everything is backwards to me

Anyone know what can be done? There are only 2 adjustments. Apparently stoich of lpg is 15.5:1

Jimmy

[raptorthumper]

I think your mixer might need a rebuild kit. I have used the 200 on several engines now and the idle screw is always able to lean out the mixture enough to cause the motor to run really badly. Is the diaphragm still nice and taught, or has it gone loose.

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[Jimbo]

It doesnt seem too bad but for what its worth i will probably just get another one.

[Northside 4x4]

Is the afr meter setup to measure gas?

If not, does it have the ability to be run in lambda mode instead of afr?

This is very common, the things you have typed. Almost all of the gas systems installed on engines bigger than about 3.5-4L have mixers far to small to supply the right amount of gas. Add to that how restrictive they are to the intake because they are so small.
The only solution was to run two mixers on most of them.

You ideally want it around AFR 15.5-16:1 (Lambda 1-1.02) at idle and cruise, then about 13.8:1 (Lambda .83-.84) under full load.


You should start by turning the hispeed mixture screw outwards until you get your full load mixtures right so it doesnt damage the motor.

[Jimbo]

Yes it can run Lambda so i may do that. The guy at the local LPG tuning place wanted $130 for the mixer diaphragm!!! Anywhere online where i can get one? Also what is the difference between the "Clean air" and "Feedback mixers"

[pcman]

http://www.bluelpg.com.au/" onclick="window.open(this.href);return false;

or buy from the usa if your patient


clean air is normally for older carby engines , feedback has computer control , on your 200 there should be a sticker and the number will be either fb200 or ca200

[raptorthumper]

This guy has brand new impco 225 mixers (flow a little more than the 200 series) for $195 or 200 series mixers for $190 posted.

http://www.ebay.com.au/itm/NEW-GENUINE- ... 4cfaa93e66" onclick="window.open(this.href);return false;

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[Jimbo]

I saw that yesterday....pretty cheap!!

I shimmed the valve today (took around 7 tries of paper thin shims) and leaned out the part throttle and midrange. Worked fairly well and i can now adjust my idle! Patrol doesnt feel any different to drive. Hopefully it uses a little less gas.