x1/9 carb to fi conversion help

But I believe there is advance circuitry in the GM module to supplement the mechanical aspect of the distributor. I'm not that versed on the domestic stuff so that may be incorrect...just what I read elsewhere.
 
But I believe there is advance circuitry in the GM module to supplement the mechanical aspect of the distributor. I'm not that versed on the domestic stuff so that may be incorrect...just what I read elsewhere.

Just to prevent confusion on the subject: there are 7-pin versions that have some timing control. The 4 pin one used here for X1/9 setup does not.
 
Hi all iam new here, iam from the otherside of the pond uk, i have a 1979 1500 carb model and i would like to convert to injection, have the manifold,air chamber,injectors ecu, fuel rail and pressure regulator, cold start injector and wiring and air flow sensor and intake hose, i think i have most bits
What other items would i need for the conversion, i also would like a wiring diagram for the double relay pinouts, this coversion is not for power but better running and starting, any help and ideas, and any part numbers for the missing items, John

This is pretty similar to the job that I had when converting a FI car to use a modified carb head. The main issues that you will have are:
  • you need to "notch" the head to allow for the spray pattern from the injectors and use an appropriate (FI) intake gasket
  • you need to use a FI thermostat housing which has the provision for a temperature sensor used by the fuel injection controller
  • you need the "cold start" components (well, they are not actually compulsory but probably good to have in the UK). This is essentially the auxiliary air valve, thermo time switch and cold start valve.
For the first problem, you should simply look at the intake manifold and compare the notching. The second problem is solved my procuring the FI thermostat housing.

For the cold start components, the issue is that there is no provision for them to mount to a carburettor head. To solve this, I made up a controller using an Arduino (micro controller) that used the existing temperature sensor (in the head) to determine the engine temperature and then controlled a PWM valve (to replicate the function of the auxiliary air valve) and to control the cold start valve (via a relay), to replicate the function / logic of the thermo time switch. As an additional benefit, there were fewer mechanical parts, a cleaner engine bay and a more progressive cold to warm transition.

Cheers,
Dom.
 
You'll need the FI-based Ignition distributor, wiring and box also - the carb advance curve is wrong for FI.

Hi Hussein,

I'm not sure that the bosh distributor's advance curve was designed so much for the FI system as for emissions reasons. I'm using a curve similar to that in a S135 Marelli distributor with my FI motor (albeit with a modified head) and it performs better than with the Bosh distributor and without any pinging at any rev range. I'm pretty sure that the advance curve of the standard Bosh distributor is very much on the conservative side.

Cheers,
Dom.
 
Dom

Nice one on using the Arduino, I assume it lives inside the spare tire compartment? Assuming you used a 12v normally closed valve? If so you likely needed to add a board to control it? Or did you make one up yourself?

I have been thinking this would be a good way to add a PWM fan to my 850 to change the way the coolant system works (electric fan and electric water pump, each with a Arduino and PWM board to drive them) as I am also putting in a higher amperage alternator to be able to drive all of this. This is to manage the power use of the cooling system on the car and simplify the bets etc.

Thanks and sorry for dragging this off topic.

Karl
 
Last edited:
I seem to recall the difference in timing curves for the carb vs. FI dizzy's was the length of the slots on the advance base-plate; one having longer slots to allow more travel. And the vacuum module's degree of "pull". I believe there was an old thread where the plate was modified (changed the slot size) and vac module replaced to achieve the desired timing curve.

Huss, could the 7-pin GM module be wired-in (similar to how the 4-pin version is used) to offer any timing advance benefits in place of the stock spark box? Not sure how it would interface with the mechanical advance of the dizzy...perhaps replace it (lock down the mechanical) or enhance it?
 
Dom

Nice one on using the Arduino, I assume it lives inside the spare tire compartment? Assuming you used a 12v normally closed valve? If so you likely needed to add a board to control it? Or did you make one up yourself?

I have been thinking this would be a good way to add a PWM fan to my 850 to change the way the coolant system works (electric fan and electric water pump, each with a Arduino and PWM board to drive them) as I am also putting in a higher amperage alternator to be able to drive all of this. This is to manage the power use of the cooling system on the car and simplify the bets etc.

Thanks and sorry for dragging this off topic.

Karl

Hi Karl,

I used a 2 pin Bosch idle control valve, similar to this one:

http://www.ebay.de/itm/362003349993

I can check the exact Bosch part number tomorrow, but it doesn't matter that much.

For the drive circuit, that is the real advantage of the Arduino community: you can get mist of these things pre-built and for very little money. You simply need a h-bridge controller like this one:

http://www.ebay.de/itm/321732349566

I also added a higher current alternator in my X1/9, but note that will only help with charging. When you are sitting in a traffic jam with the cooling fans on, typically the alternator won't be doing much. To compensate for this, I added a second battery (Odyssey Hawker PC680) which cuts in under these conditions (fans on, at idle) and also at high RPM (to allow it to charge). Of course, all controlled from the Arduino ;-).

Dom.
 
I seem to recall the difference in timing curves for the carb vs. FI dizzy's was the length of the slots on the advance base-plate; one having longer slots to allow more travel. And the vacuum module's degree of "pull". I believe there was an old thread where the plate was modified (changed the slot size) and vac module replaced to achieve the desired timing curve.

Huss, could the 7-pin GM module be wired-in (similar to how the 4-pin version is used) to offer any timing advance benefits in place of the stock spark box? Not sure how it would interface with the mechanical advance of the dizzy...perhaps replace it (lock down the mechanical) or enhance it?

Hi Dr.Jeff,

note that with any of the standard distributors, none of the control modules will impact the advance curve at all. At best, they will control the dwell for you. The advance is all controlled (mechanically) within the distributor. More modern systems had intelligent ignition control but the distributors for these systems have no advance whatsoever (no weights, no vacuum line).

Some good info here:

http://www.dtec.net.au/High Energy Ignition Upgrade.htm

Cheers,
Dom.
 
Thanks Dom. Hussein enlightened me on that, so my thought was to either augment the mechanical advance of the distributor with that of the new-style module's electronic circuitry (the type of 7-pin module that has such circuitry), or replace the mechanical advance with the electronic one, which ever would be appropriate. Very nice article in your link, thanks.
 
Hi Karl,

I used a 2 pin Bosch idle control valve, similar to this one:

http://www.ebay.de/itm/362003349993

I can check the exact Bosch part number tomorrow, but it doesn't matter that much.

For the drive circuit, that is the real advantage of the Arduino community: you can get mist of these things pre-built and for very little money. You simply need a h-bridge controller like this one:

http://www.ebay.de/itm/321732349566

I also added a higher current alternator in my X1/9, but note that will only help with charging. When you are sitting in a traffic jam with the cooling fans on, typically the alternator won't be doing much. To compensate for this, I added a second battery (Odyssey Hawker PC680) which cuts in under these conditions (fans on, at idle) and also at high RPM (to allow it to charge). Of course, all controlled from the Arduino ;-).

Dom.

So the idle control valve is the same one VW uses across a bunch of cars. Easy to find both new and used. Thanks!
I was looking at that board earlier, works up to 34v but does drop the voltage but likely not much of an issue as most fans and pumps will be too powerful for an 850 anyway so a little slower won't hurt.

Thank you.
 
I don't yet but expect I will need one to Mega Squirt one of my two X's

Volvo used those for a donkey's age, also - you could prolly get one for $5 in a JY, if they exist around you. That's what I used with my LH2.4 conversion. I can always mail you one of the many spares I have for the cost of shipping if need be :D
 
Back
Top