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Discussion Starter · #1 ·
All,
The question is, how to get sequential spark and sequential fuel running in the Alfa Twin Spark.
The reason why this is 'hard' is because there isn't a cam driven sync signal.
You need to tell your ECU not just where the crank is, but also when in the 720 degree rotation of the crank the crank is on the compression stroke for cylinder #1.

There are a couple options that I have found to get a cam signal.
There is an AEM EPM (Engine Position Module) which apprently can give a crank signal and a cam signal all from one device.
Has anyone used something like this?
Engine Position Module (EPM)

One other option is to keep my crank signal from the stock hall effect sensor.
And just get a 'home' signal from my distributor running off the oil pump.
Idea's for cobbling together a home-made solution for this:
DIY TCI + CDI Trigger Article
914World.com - The fastest growing online 914 community!

Anyway, was wondering what others have done to gets this signal and run a full sequential spark and fuel.
Thanks
Ian
 

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Discussion Starter · #3 ·
Great idea, and if it's working for you I am very interested.
How did you 'fit a cam sensor', got a build thread I can take a look at?

Got a photo of how / where you fit your's?
Was it a wheel and hall effect on ferrous metal? Hall effect and magnetic firing? or a Variable reluctance sensor somehow?

Thanks
Ian
 

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Discussion Starter · #4 ·
Additional Thoughts from AEM Support

From AEM Support team via email:

"If you’re planning on using the AEM EPM for both a crank and cam signal, then it will need to spin at camshaft speed (half crank speed) since the sync reference, or cam signal, needs to occur once per engine cycle (every two crank revolutions). As far as I know, distributors always rotate at camshaft speed, since they too need to repeat their firing order once per engine cycle, so the oil-pump driven distributor shaft should be fine. Many V8s like Ford 351s, Chevy small/big block etc have this same setup and we have a replacement EPM that drops right into those engines and it works great like that.

You could also mount it on either the intake or exhaust cam gear. Either way, any of these options will allow you to run full sequential fuel and spark."

So, apparently if you want to use the EPM it is an option.
Ian
 

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Great idea, and if it's working for you I am very interested.
How did you 'fit a cam sensor', got a build thread I can take a look at?

Got a photo of how / where you fit your's?
Was it a wheel and hall effect on ferrous metal? Hall effect and magnetic firing? or a Variable reluctance sensor somehow?

Thanks
Ian
Is a Hall effect sensor, provided by DTA. Have not fitted it yet. Some delay due to late deliverance of the cams and ITB`s.
 

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Discussion Starter · #6 ·
FYI...I have purchased the AEM unit

I have gone ahead and purchased the AEM EPM 30-3250.
This 'Engine Position Module' will give a signal off the distributor / oil pump drive.
It will give a crank signal with a 24 tooth wheel, and a single pulse every full rotation to signal a 'home' or compression stroke on cyclinder #1.

I can always still use the crank signal off the crank pulley, but for keeping things as reliable as possible, I am thinking updated electronics in the AEM EPM will be better in reliability compared to using the old Bosche part and then a coubled together custom part for the 'home signal.

Will keep the thread updated when I get the part in to document the modifications that are required to 'adapt' this universal module to the distributor.

Also, looking forward to seeing/hearing the DTA setup that VEEP has coming in for his cam signal ;)
 

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Nice to see the want for full sequential. But really, unless you have a particularly mad engine with big injectors, there's probably no real benefit.
Being able to set injector timing may bring some rewards, tho. If your chosen ECU has the capacity to do that.

24 tooth, cam speed CAS???
Toyota used that way back in '88 on the 4AGZE engines with ECU's clocked by a sun dial.

And Bosch 60-2 CAS use Variable Reluctor, not Hall Effect sensors.
 

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Discussion Starter · #9 · (Edited)
I agree, the 'benefits' are not there from what I can read.
However, I just want it running as 'good' as I possibly can, and whether that is fuel economy related or not, I feel like injectors pulsing at the time the charge is being drawn in feels like the best approach to me.

Adding some pictures because pictures made threads better.

Alfa Romeo Twin Spark 8v - crank Position Sensor Hall Effect Bosch by Ian Bennett, on Flickr

The 'old' sensor on my crank that came with the engine.

Alfa Romeo Twin Spark 8v - crank Position Sensor Hall Effect Bosch by Ian Bennett, on Flickr

Setup of the AEM EPM

Alfa Romeo - AEM EPM for sequential fuel and sequential spark by Ian Bennett, on Flickr

Specifications

Alfa Romeo - AEM EPM for sequential fuel and sequential spark by Ian Bennett, on Flickr


Nice to see the want for full sequential. But really, unless you have a particularly mad engine with big injectors, there's probably no real benefit.
Being able to set injector timing may bring some rewards, tho. If your chosen ECU has the capacity to do that.

24 tooth, cam speed CAS???
Toyota used that way back in '88 on the 4AGZE engines with ECU's clocked by a sun dial.

And Bosch 60-2 CAS use Variable Reluctor, not Hall Effect sensors.
 

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Discussion Starter · #10 ·
Just some more photo's.
The device arrived (shiny powder coated aluminum billet parts are sexy).
However, I need to build an adapter for this thing to fit our bosch distributors on the twin spark.
Some facts I can see about the unit itself.

1. water resistant with a nice o-ring, but probably not water proof for boats/powersports on water type stuff. VERY good for a car though.
2. solid aluminum
3. looks like 14 gauge wire for the senders etc.
4. comes with the femal plug attached to the unit, and a wire-ready male plug to be soldered onto your harness.

measurements box to my friend who has a 3d printer
AEM EPM adapter fabrication by Ian Bennett, on Flickr

Example of an adapter bolted together to a 22re distributor (very differant than our alfa's)
AEM EPM adapter fabrication by Ian Bennett, on Flickr

A EPM EPM adapter someone else made and is available to purchase (but I don't think it's the right size for the alfa)
Available to purchase here:
https://www.shapeways.com/product/E...aem-epm-puck?optionId=61641595&li=marketplace

Photo of the adapter for purchase.
AEM EPM adapter fabrication by Ian Bennett, on Flickr
 

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A little confused by your pictures. They don't look shiny and billet. They look old and used. Did you send them your distributor and they fitted their device, or did they sell you a used distributor?

Does the distributor cap fit over it?
 

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Discussion Starter · #12 ·
The shiny new part is the AEM piece, it is black, and has a little silver tab.
The distributor is my original distributor, and the cap is the original cap.

You use the distributor and the cap to help make the custom 'puck' you need to adapt the AEM unit to your old distributor.
Probably the long way around the block to get this to work, but such is the life in a project car!


A little confused by your pictures. They don't look shiny and billet. They look old and used. Did you send them your distributor and they fitted their device, or did they sell you a used distributor?

Does the distributor cap fit over it?
 

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Discussion Starter · #15 · (Edited)
Veep (and others)
To do fully sequential spark and fuel, your ECU/computer needs two measurements. The position of the crank shaft, and the position of the cam shaft.

The twin spark can easily give the position of the crank (factory EFI used a crank sensor for batch fuel injection) but the engine does not have a camshaft position sensor. So you need to fabricate something to work.

You can attach a wheel to your intake cam shaft, but I didn't like the idea of modding the camshaft (incase any future cam shaft is replaced/installed).

So, to get a camshaft position (or rather to tell the ECU when the engine is on the compression stroke and not the exhaust stroke) you can use the distributor. The distributor turns 360 degree's for every engine 'cycle'. the crank shaft turns 720 degree's, so with a device that can measure these turns (360 degree's and 720 degree's) the ECU can then do injection and spark sequentially.

This is the furthest I have gone to understand it without an assembled engine and parts, but I will keep the thread going when I learn more and explain (for anyone else who wants to do fully sequential fuel and spark).


I am a little confused...why use a distributor when you want to use a computer on the EFI...??
 

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To add a little to IanB's comments, the camshaft speed/half engine speed sensor simply provides a reset to the ECU so it knows what half of the 720* cycle the engine is in.
Some cam speed sensors have 180* of trigger edge so that the ECU can figure out as early as possible during cranking where the engine is. After all, the ECU won't know where the engine stopped when the ignition is switched off and it has to figure that out by having the appropriate reset edge go pass the sensor.

A classic example would be for the Bosch 60-2 CAS with no cam speed reset, where the engine has stopped just after the minus 2 reset point. The engine must be cranked a full turn before the ECU can fire injectors or ignition, because it just has no idea where the engine is in its rotational position. But in the mean time, on a 6 cylinder engine, 3 induction strokes, 3 compression stokes and 3 exhaust stokes will take place. And that causes strain on the starter motor and drain on the battery.
 

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Discussion Starter · #17 ·
Ok, fitment continues!
With my back-woods, garage monkey approach, you'll see the brilliance I am trying to create with these photo's.

For anyone else attempting to do this.
Next time, just buy the **** black plastic adapter (linked on page 1) and adapt that to your distributor.

Now, onto the craziness I chose to take on.
Bought a 4x4x1 aluminum block off ebay for 12$ shipped (in hindsight a 1/2" thick one is all I needed).
Mill it with your router, drill holes with your drill press, make it perfectly centered on everything.
Fit it together, and you find the rubber tab slot for your distributor needs to be .22"...the Alfa is like .18" (to narrow).
Break out the angle grinder and the dremel, slowly....slowly grind away till you think it fits.
Spend about 2 hrs, still doesn't fit....take a break and come back at it tomorrow.

Any idea's on making my own 'custom' rubber piece for this fitment?
So far it's a 7-10 on the fabrication scale, 10=e-type jag rolled fender, 1=self drilling screw through metal fastener install.

drilling
AEM EPM - Install and adapter and fitting by Ian Bennett, on Flickr

milling to thickness
AEM EPM - Install and adapter and fitting by Ian Bennett, on Flickr

'finished' adapter plate (still not sure if it's finished, but it does fit.
AEM EPM - Install and adapter and fitting by Ian Bennett, on Flickr

No Mas
AEM EPM - Install and adapter and fitting by Ian Bennett, on Flickr

How thick the gap in the distrutor 'slot' should be in MM.
AEM EPM - Install and adapter and fitting by Ian Bennett, on Flickr

Work continues and so will the photo's till this thing is 'done'.
Still might spend the 45$ for the printer one, but probably to deep into this BS aluminum already, and it's not what's holding me back.
It's the slot int he distributor that's holding me back right now.

Ian
 

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Discussion Starter · #19 ·
@IanB

Did you ever get this to run?

Thanks
Alessandro


The plan is to still use this setup. Head has been at the machine shop for 5 months, but I think will be ready soon. ECU won’t be purchased till next spring and then we’ll crank for the first time and try to get some signal off this contraption.

However, a friend on Instagram tried this very setup with a fully machined adapter and for whatever reason wasn’t able to get a signal. So, with that experience I am worried this may not work. My friends fall-back was the normal crank sensor and going to batch fueling not sequential. We’ll see what my fate is next year.

Ian


Sent from my iPhone using Tapatalk
 
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