impco 200 super lean!! help

Propane, Butane, LPG, GPL, C3H8, C4H10
Steptoe
Posts: 1504
Joined: Fri Feb 02, 2007 8:32 pm
Location: JAFA , New Zealand

Re: impco 200 super lean!! help

Post by Steptoe »

This is the first I have heard of wc testing in my fight! .....only found wc testing in reference to natural gas furnaces. Can you give me a verbal lesson.
Run a forum search here.. couple years back.. pics and how to make a accurate water column gauge out of a bit of hose , scrap ply and couple screws... and also where to connect etc.
Hang on pic still on my server somewhere..
yep here it is :D
Image
My Spelling is Not Incorrect...It's 'Creative'

bumpstart
Posts: 133
Joined: Wed Jan 20, 2010 9:09 pm

Re: impco 200 super lean!! help

Post by bumpstart »

thinks im a little late on this one .. first,, thumbs up for the manometer pic,, takes me back to when i had to tune a fuel injected ducati and had to balance the TB's.. made an impromtu setup with a board , loop, and an icecream container lid with a hole in it
i think i still have it in the shed somewhere ..

OK.. for the OP ...
...i have a similar system but a 225 ..

my first observation is the statement where you have only 2 psi at the convertor " at all times"

,, under boost ,, the convertor pressure should rise with that seen at the "air valve vacuum point" and be about 2psi over and above that seen there

im thinking there is a problem with where you have source the boost reference from ,, and if hooked after the air valve.. or worse,, after the throttle plate .. they will make the mixes excessively lean
( indeed the feedback systems on later 200/225 use duty cycle and a three way valve to use these excessive vacuum sources to modulate reference signal thus the vapour pressure )

you need to draw the source from the "bonnet" above the air valve,, on a 225 their is several bung provided for you to replace with a 1/4 fitting suit the job
.. for a while there i even tapped a 3/16 fitting into the ( removable on 225 ) bonnet directly

on a 200 i think its on the underside of the air inlet entry and says "balance"

once you hook up here you will find the standard air gas valve is fine
.. if still a little lean then you may find you have a shim between the gas valve and the air valve
remove this to go richer .. and you must re-install both of them with correct orientation to get consistent mixtures
- pay attention to the square locating tang on the air valve,, and the orientation of the grooves in the gas valve to the gas inlet ..
when the going is hard, don't retard, remember your lubrication

strike
Posts: 9
Joined: Sun Dec 01, 2013 10:21 pm
Location: Seattle washington

Re: impco 200 super lean!! help

Post by strike »

I have the 200 hooked at the balance tube on the underside of the bonnit like u described, it has been from the beginning. I did have 1/4" balance line but replaced with 3/8. Afrs are only lean at idle, good any time above about 1800k and perfect when boost come on! Engine wouldn't come into boost when blalance tubes wrong. What I had done is screwed up my vpv, I miss understood. Everything is now correct size and run correct thanks to C3H8. It is still lean at idle but not as bad. I have been to busy in a few days to fiddle. There is no label on the air valve or the bullet? ANY WHERE! I order the richer air valve a few nights ago but won't be here for a few days. I still want to change the ristrictor on the vpv and play with the adjustment Allen, the vpv is as it came with the 4 cyl ristrictor in it.

Thanks

Ps. 2 psi is at primary port, secondary is what is about 2 psi above boost pressure.

C3H8
Posts: 1129
Joined: Fri Sep 09, 2005 11:23 pm
Location: Winnipeg, Canada

Re: impco 200 super lean!! help

Post by C3H8 »

I think your beginning to get the picture pretty good. Quick correction. Primary pressure will always be 1 to 2 PSI on a normally aspirated engine. Primary pressure will always be 1 to 2 PSI above boost pressure on a TC or SC engine. Secondary vacuum is -1.5" WC differential. The secondary vacuum will always be -1.5" WC lower then the air valve vacuum.

No markings on your gas valve at all. That's puzzling. Is there any chance this is a knockoff air/gas valve assembly. I don't think I have ever seen an IMPCO carb with an unidentified gas valve or unidentified bullet. I may have made a error in telling you where to look. Since there is no label look on the top of the gas valve assembly where the bullet is riveted on the top side. The assembly should have numbers cast on the top side where the diaphragm sits inside the circle of the tin plate held on by four screws. If this is a knock off I would suggest you try a factory assembly before jumping to the rich valves. One way to tell if it is a knock off is some of the knock offs had the bullet held in place with a screw. IMPCO factory units are riveted to the metal barrel portion.

Bump start referenced the leaning washers used on some of these units. It is not normal to have these on a standard 200 straight out of the factory but it is possible. I referred to the slotted plate previously. The leaning washers are used between this plate and metal portion of the gas valve. If any of these shims are present they just need to be removed to richen the mixtures. These rings were used primarily to make the mixtures really lean on forklifts. They are made of brass for the 200 series and are .003" thick.

jono
Posts: 365
Joined: Wed May 16, 2007 11:46 pm
Location: New South Wales, Oz

Re: impco 200 super lean!! help

Post by jono »

Hmm, must come in here more often ...

One month later and nothing in this post.
Now, if I had been in here could have suggested that this fellow is going down same stupid path I went down. Leave the 200 alone, poor thing :(

Been there, done that and find most in here play with sixes and eights and rarely fours, let alone turbo fours.

I had a beautiful set up of a 200 mounted on the throttle body with turbo blowing through it on an 1800cc flat four- near undriveable due to intake pulses of a turbo four cylinder create havoc. I mucked about with balance line internal diameters and found the smallest the best, but still poop to drive. Flipped it all about into a turbo sucks vapours through it and not looked back - getting perfect emissions at tailpipe past the cat. Precat is a bit rich if anytthing and is gonna get a leaning ring next drive. Done 80,000km on this propane system set -up ,and about 2km with turbo blow through.

Curious to see how you go. 22R is Toyota something isn't it ?

I see non IMPCO air valves are just blank, no indicator of what it is rated, no tip mark, no hand written gradings, nothing

jono
Posts: 365
Joined: Wed May 16, 2007 11:46 pm
Location: New South Wales, Oz

Re: impco 200 super lean!! help

Post by jono »

I should have hit edit - oh well....also should mention the feedback systems use components that are for vacuum only, not boost, so a "turbo draws through mixer" set-up is likely only for fresh air not feedback :( mentioned just in case you have a feedback sytem - thanks C3 :)
Last edited by jono on Wed Jan 08, 2014 8:46 pm, edited 1 time in total.

C3H8
Posts: 1129
Joined: Fri Sep 09, 2005 11:23 pm
Location: Winnipeg, Canada

Re: impco 200 super lean!! help

Post by C3H8 »

Jono: There is no mention of feedback on the system so I expect you just added that for reference. As for the 4 cylinder pulsing. That is a very good point. I had not considered that and failed to mention it. Pulsing can be extreme on 1, 2 and 3 cylinder engines to the point where they will wear out a mixer very quickly. 4 cylinders also pulse fairly strongly and could cause issues in either a draw or push system, however I expect you are correct that the push through would suffer from this condition more.

Good point.

jono
Posts: 365
Joined: Wed May 16, 2007 11:46 pm
Location: New South Wales, Oz

Re: impco 200 super lean!! help

Post by jono »

and it is the pulsing of turbo 4 cylinder that caused my issues. a NA 4 cylinders seem to be fine - no turbo causing issues :) I have one IMPCO 125 mixer that must have 500,000km on it - only kitted it as a preventive maintenance thing :)

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