Impco system propane carb setup questions

[Delifisek]

Hello,

Finally I import some chinese made impco knock off propane carbs. (25 USD each). I setup easly And I have some questions about...

I had 2.800 cc (170 cid) v6 ford cologne engine which had 34/34 weber carb, plus had a Mercedes Benz coil for better spark power.

I had 15.5 afr on ide and 4500 rpm.

Also I removed choke system from my carb. (complex regulators already had some choke effect, with static mixer choke less operation was not problem)

1-) Cold start and start take too much time. It takes 5 to 10 seconds to fire up engine. Then I got very unstable idle for a 30 seconds in coldstart. I'm sure, in winter it becames worst.
Is chokeless carb lead this problem ?

2-) what is cruse setup rpm. For controlling I add feed valve to main lpg pipe. Our normal procedure tune car for load at 3000 rpm. However in this time when I setup at 3000. I goes ultra lean at 4000 rpm. And if I remove the feed valve. at 1500 and 2000 rpm it becomes rich (14.2).

Thanks...

[Steptoe]

A choke is there to give stable idle when an engine is cold...
I dont use a choke... winter here amounts to a few fosts that are gone by 9:00/ 10am...the engine idles rough but stable at 450 rpms after a 30/ 40 second warm up... and full stable after turning and driving up a 50M drive... thu not regist anything on the temp gauge at that point.

1-) Cold start and start take too much time. It takes 5 to 10 seconds to fire up engine.

Covered in many older posts, discussed by many from very differing summer and winter conditions.
I believe the general consenis is like this..
In my circumstances.. I dont use a pre primer.... be it summer or winter tacks 5 to 7 seconds (if the car has been run in the last couple days) and fires
The inlet manifold, carb/ LPG feed tube to the carb are all MT... The engine turns over, then the shut off, electrical Vacuum whatever gets activated, then gas starts to flow thru from shut off and takes a few seconds to get past the engine valves, get to a good mixture requirement and then fires.....
I feel the advantage of this is that at this piont the oil pressure is up at piont of fire.. not loading a completely dry engine.
I could use a primer, but by the time I prime, I may as well be getting oil pressure up...
Then there are those who have a few inchs plus of snow on the ground...these people tend to use a primer to fire up in most cases.
For the rest of the day... inlet manifolds already have full, oil around engine, firing is near instantaneous

[Delifisek]

Thanks for answer.

I'll try with choked carb. Before the propane carb I do not have any long startup problems. Today 35 celcius and it has same 5 second crank time. Most of my setups has instant cranking...

Well, so where is my dual 38 .....

[BigBlockMopar]

Do you have any pics of those China carbs?

A long cranking time usually means a lean starting situation (or a small leak somewhere).
My car's morning start usually happens before or at 2 seconds of cranking.
Now that I leaned out the mixer quite a bit because of warmer outside temps, it starts within 2-3 seconds from the moment I turn the key.

[Delifisek]

I found the error.

In my setup, I had propane carb => 20cm intake pipe => custom carburettor hat => then carburettor => riser => intake => engine.

So ? its a long way form vaporizer to engine. On first start it takes time to reach lpg to engine.

Also I'm shutting down engine via LPG on off switch. So when my engine stops I suck every gas on the intake.

Yesterday I do not bother the switch off engine from lpg switch and use normal way. After some shopping my car starts instantly. Then I start to do some tests and confirm the problem.

In my setup, my pipeline bit long.

So it was working perfectly...

Anyway. Thanks for support.

My humble regards.

[Steptoe]

you mean that 1" pipe from converter to carb?
If so, then sorting up u will also notice the engine a bit more responsive.

Also I'm shutting down engine via LPG on off switch

.
Im not sure i follow??
you turn off an electrical(???) soleniod to the LPG, before the converter?Then turn the have a key off?
Why not not have a vff vaccuum shut off before the converter... no engine turn over no LPG.

[Delifisek]

I should have to take photos...

No, Vaporizer to LPG carb pipe was very short. Even shorter than last static mixerr setup.

I mean my new LPG carb was bit away from gas carb. It was too tal and I cannot fit over the of of my gas carb. So I build a carburetttor cap / hat



And I cannot fit LPG carb to this hat. There where another pipe from hat to lpg carb. And it takes time to fill all these way with lpg.

But after first start it was brillant. It start from first crank. Almost immediately. Very impressive.

Also about solenids.

In our county almost every lpg conversation has dual fuel setup. Our cars has 3 point selector for fuels. Which Gas / off / LPG.



Also this switch box contains some kind of engine running detector via igntion coil or ignition plug cable. if your ignition coil does not produce voltage, switchbox auto close solenodis after 3 seconds There where no vacuum shut off in Turkey. I did not see any of them and I hear first here.

Until last week I almost off my engine via switch to middle. When I swith to middle 3 solenoid valfs (one in tank, one before regulator, one in regulator) goes offline then my engine shuts down after sucking every bit of vaporized LPG.

When I was starting learn to drive, one of my friends which runs electrical shop mocking me to if you left this on for gas (like shon like the picture) my car maybe explode. Like any other enthusiastic noob I buy this claim and develop habit to shut off engine from lpg switch.

After learning truth, I contiue to run my car with this way. Until last week

[Steptoe]

"In our county"
"There where no vacuum shut off in Turkey."
Thgere have been many posts over the yrs for people top put their country of orgin in as this very often make clear many things quickly, any thing from the above to simply talking miles per gal and unit sizes.

[kikkegek]

Do you have any pics of those China carbs?

welcome,

I would also love to see pics of that chinese product and your car installation.

[Delifisek]

Hi there,

I had one question about tuning. When I direct connec from vaporizer to carb it was running about 14.2 afr. And I want to run lener (let say around 16.0). I presume, fitting harder sping to main membrane will solve the problem.

Did I miss something ?

Also

I still not have any installation pictures. This one from producer.

[kikkegek]

he thanks man,

got any specs or instructions for it?

[Delifisek]

No instructions,

manufacturer says it will support max 160 kw.

You need custom carburettor hat, it does not come with throttle valve, so you have to fit by yourself. we weld some kind of carburettor hat.

Performance

I had clutch problems so my takeoff from first gear was sluggish, after 1300 rpm it responses better than static mixer. Also it was feed engine almost same afr in every rpm range.
However It needs direct link to vaporizer / reducer.

Tuning (so far)
First of all it was my first time this kind of device.

On first tuning I see rich 14.2 afr then I put a valve on feed pipe. Our crusing tuning habit was put engine 3000 rpm then find corret value. After tuning I start some testing on highway. Car start to cut off after 3.300 rpm. After some check I found this device does not like any block on feed pipe. It does not respond like static mixer. Even if you setup afr for 4500 rpm it will cut off at 5000 rpm.

Also fuel consumption was higher than usual. Even I'm on economy carb (Dual 34 weber) I can see 17 litre per 100 km on urban.

Tomorrow my car enters the body shop and we will start to remove rust from under carriage. Then I plan medicore overhauling for streering and gears.

After than that I can give reliable fuel consumption. Also, due to spring loosenes I'm running bit rich in these days.