i have an impco 425 on the 351 in my f100. i am trying to establish which air/gas valve is in it. it has AV1-16-2 600718 on it. does anyone know which one it is ?

well, did some looking on google, and found out it is the standard one.

I've heard about this on the 425 but haven't messed with it.
My 425 was on my car for about 12 months, i bought it new and bolted it on running an E type convertor, man it SUCKED the gas big time... I'll have to check into this when i finally put it back on the road.

yep, mine too. that's why i was checking the air valve. the std one is supposedly for a 350-ish cube engine. i reckoned it would be good for the 351 in the effy. better then the mega gas setup, but not much. how hard is closed loop control to set up on a complex converter system ? is it just bang the stepper in the vapour hose and an oxygen sensor in the exhaust and wire it all up ?

Yeah i think so mate, i haven't actually looked at a stepper motor for the Impco as yet, if i were to set it up on my XD again then i think i'd seriously look into doing something like that.

hey brian

have you seen this webpage?
http://cars.rasoenterprises.com/Propane ... xtures.htm

heaps of info on 425

my vacuum controlled closed loop setup im running doesnt seem to be the best setup. I knew impco gear was a bit thirsty to begin with but I think the mixer ring setup would be more economical.
I wonder if you can use a stepper motor setup in the vapour hose of an impco setup. i can't see why not.
for 3 months i had a new bf wagon e-gas for a company car it was cheaper to run and not as thirsty as what i have on my ef.
i dont have any exact figures but on the weekend i drove to armidale and back i kept my receipts and I got 15.5L per 100km of gas. this was sitting on 100km/h sometimes 110 thats it.
the trip meter told me (on the dash) i was getting 12.5L/100 but it mustn't be accurate now with the lpg tank hooked up to the original fuel gauge.
with the distance to empty showing 20km and the fuel gauge below empty i could only put 55L of gas in the tank. My tank is 90L with a useable 72L(80%) so it must still have 17L in the tank when the gauge says empty.
im not complaining though, at least I know I won't end up stuck on the side of the road!

what sort of economy are you getting with the f truck?

may as well give some background. i bought the effy 15months ago. it had a 600 vac sec holley on it and a mega gas complex converter dual fuel setup on it. this worked ok, but it would only give me about 30l/100k's. this ended up coming loose and it burnt the boosters out of the carby. ( halfway between tibooburra and innamincka, beautiful. ) i cracked it when i got home, and put a 425 on, along with an edelbrock performer. the drama i have is that straight gas limits my range. i would like the dual fuel setup back, so i can go places. the mega gas setup opens up when on petrol and really doesn't seem to affect petrol consumption. how hard would some sort of closed loop setup be to fit to the complex mixer setup ? not hard i assume ? if i could get the gas consumption down, this setup be the best of both worlds for me.

I have a Gastec IMP6 closed loop vacuum type controller.
I think it cost me about $202 trade from pro gas.
It was a piece of piss to wire up, it only took a couple of hours.
easy to tune too.
One of these should make an improvement.

Read the wiring diagram and hose connections here:
http://www.gastec.ws/gastec_pdf_files/Imp6Apdf.pdf

Installation Instructions for IMP6 (size = 101k)
http://www.gastec.ws/gastec_pdf_files/I ... rTextA.pdf

The sales brochure is here:
IMP6 Brochure (size = 120k)
http://www.gastec.ws/gastec_pdf_files/IMP6BrochB.pdf

Albert lamb did recommend that i get a PEEL CP201 Processor. ($200)
http://www.peelinstruments.com.au/products.html
but i rang them and they wouldn't sell me one direct nor recommend a supplier I could get one from because I wasnt a licensed fitter.
I told them to jamb it up their a*** and I bought one from progas.
I couldn't understand why they couldnt sell it to me. wankers.

have you put an o2 sensor in it and connected a multimeter?

Set the idle and road cruise as close to .450 mv as possible (only use a digital volt meter) and at full load, look for around 650 to 700 mv.
You will not achieve these numbers exactly but anything close will be pretty good.

My 225 mixer with the feedback air valve sits on about .750-.800mv full load and it has the smoothest and best idle at about .820mV
I just leave it in closed loop at idle, the mirrors buzz a little bit when it goes lean but there no popping out the tailpipe. its running really well at the moment. its s**t how well it idles on lpg. ive never seen an e-series idle so well. usually they idle like crap.
most of what i have read says that lpg runs better a bit lean or spot on stoich. mine is a tad rich but i think it goes better rich. i thought it would run hotter too being rich but it doesn't. the hottest ive seen it get is up to r in normal on the temp gauge.

could the wrong diff ratio be affecting your fuel economy? or is the igntion timing incorrect? is the vac advance hooked up?
try driving it without the aircleaner see if mileage improves? is the aircleaner ok?

id just fit 2 gas tanks to your truck, i reckon petrol is for washing parts in and for the lawn mower.

can you get the latest street fords issue 22 out your way?
its got an article on that turbo ea, its not a bad read.
my bike is still faster than it

having the option of using petrol is handy. drove nearly 2000km once without seeing a gas bowser. that and i need all the space i can get in the tray at times. these processors both look good. i'll have to have a better look at it.

rang up my local gas place yesterday ( adelaide ! ). spoke to them about the s**t economy with my simple mixer setup. he askedme afew questios about the show and i found out it has a tiny converter attached. i am going to put it and the holley back on. i have ordered the bigger converter and will see what happens. matey wasn't real keen on lambda processors, but that is still well and truly an option.

You say simple mixer setup? i thought 425 impco's were a complex mixer/simple converter?

What converter do you have on it now?
what converter are you going to get?

I got my b2 converter on eBay, you won't find cheaper anywhere. I think it was about $180 delivered to my door overnight.
im sure 1 * b2 would be enough for the f truck.

it has a 425 on it now. i want my dual fuel setup back. so the sprintgas setup is getting another run. with a bigger converter. i will see how it goes. if it's still a bit povvo economy wise, i'll whack a lambda processor on it.

so i refitted the holley today, and the sprintgas setup. it will be interesting to see how it all goes. my converter has the sensitivity and bypass setup on it. does not having this right affect cruise economy ? or is that controlled by the mixture screw in the vapour hose ?

had trouble with the car idling on gas. foundout that i hadn't plugged the choke leverhole ! goes much better now !

gave it about 2000 k's. averaged 20l/100km. hooray ! not sure what helped it. i replaced the converter when i changed back. i wouldn't be suprised if the educated fiddling with the sensitivity and bypass helped. ( thanks fordmods ! ) i still drive at the same speeds and stuff.