General 1975 124 Spider Fuel Injection Conversion

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General 1975 124 Spider Fuel Injection Conversion

eelee

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I have been working for a while on putting together a fuel injection conversion for my carbureted 1975 124. The concept is a sequential EFI system based on a Megasquirt ECU with 4 individual throttle bodies and 4 coils installed on a Fiat 2.0L 8 valve engine.

The Jenvy ITB's came in yesterday's mail. As can be seen in the attached photo, I'm starting to assemble the ITB's today. They fit on a Weber DCOE intake that I bought a while back. I'm rebuilding one of the 2.0L engines that I've had for a while for the project. Nothing too wild, a mild performance cam shaft, EFI, forged 10:1 pistons, headers and a slightly larger exhaust system.

I modified a spare fuel tank that I had to accept a Delphi in tank fuel pump rather than using an external fuel pump, much quieter than an external electric pump. I split the tank along the seam and added some baffles along with a new ring for a GM style in tank fuel pump. I coated the inside with POR 15 fuel tank coating while the tank was split an then coated the area of the seam after welding the tank back together.

I am going to attempt to use the lobe that once drove a mechanical fuel pump to provide the trigger for the cam position sensor mounted on a block-off plate. Alternatively, I have also modified a distributor for that application as well. Using the mechanical fuel pump drive will definitely be a cleaner install if I can make it work.

The car will be completely rewired and a new 100 amp GM 1 wire alternator will replace the 45 amp unit currently powering the car. I was originally going to use a NOS Fiat wiring harness that I bought years ago but I'll probably sell that harness as it was just easier to start from scratch since the wiring mods are pretty extensive. Seemed as shame to hack up s new harness so I bought a universal harness from speedway motors for the project.

I have made new wood parts for the dash/console from several pieces of Bocote stock that I infused with epoxy and then applied a UV resistant finish on. I'll post some photos later, it came out really nicely. I took a spare dash pad that I had and made/installed a leather dash cover. When I acquired that dash the guy that I got it from gave me a steering column that I refurbished and installed a MOMO Prototipo steering wheel on that will replace the original.

As much as possible this project car will be a "bolt-on mod" project. I am refurbishing parts that I have collected over the years and will just install everything all at once. I hate to take it down during "driving season". I will be installing everything late next fall/winter if I can hold myself back that long.

I did a similar project on my son's 1985 El Camino a few years ago for his college graduation. 6 years later he's still using that car as a daily driver and has had 0 issues. Hopefully this one comes out as well as that one did. I am trying to get better about documenting the mods with photos so as this moves forward I'll post more photos and additional write-up.
 

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------------I am going to attempt to use the lobe that once drove a mechanical fuel pump to provide the trigger for the cam position sensor mounted on a block-off plate. ---------------------------------------------------------------------------Using the mechanical fuel pump drive will definitely be a cleaner install if I can make it work.
I reckon this should work but you might possibly have to trim/grind the lobe (eccentric?) down to a tooth shape to get a sharp triggering of the CPS?

You've certainly got some great ideas for modifications which you have carefully thought through and then executed/plan to execute. I agree with your plan to defer the work until the driving season has ended - cars are for driving, after all.
I look forward to more photos, maybe towards the end of the year?
 
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I just remembered something about these 2 litre Fiat engines. That eccentric (lobe) on the auxiliary driveshaft (which was used to drive a mechanical fuel pump on earlier models) that you mention - has to be timed correctly (the hole/timing mark on the drive sprocket is set 3 teeth/23 degrees clockwise from the 12 o'clock position when no.1 cyl. is at tdc.) - otherwise, iirc, the eccentric can be struck by no 2? con rod.
In other words, if you intend to rotate the auxiliary drive shaft in order to have the eccentric trigger the camshaft position sensor, be careful in so doing, that the eccentric won't collide with no.2 con rod.
 
I just remembered something about these 2 litre Fiat engines. That eccentric (lobe) on the auxiliary driveshaft (which was used to drive a mechanical fuel pump on earlier models) that you mention - has to be timed correctly (the hole/timing mark on the drive sprocket is set 3 teeth/23 degrees clockwise from the 12 o'clock position when no.1 cyl. is at tdc.) - otherwise, iirc, the eccentric can be struck by no 2? con rod.
In other words, if you intend to rotate the auxiliary drive shaft in order to have the eccentric trigger the camshaft position sensor, be careful that in so doing, that the eccentric can't collide with no.2 con rod.
 
I'll definitely keep that possible interference in mind as I look at that option.

At this point I haven't determined if it will or won't work. If it will work, it will make for a much cleaner looking install. It's one of more than 100 things to look out for as I proceed with my EFI/ignition conversion. It'll be interesting, not for the purists who need everything to be original, but it will suit me.

My 75 is no show car and I am well aware I'll have more in it than it's worth. I'm okay with that, the car makes me happy. Somethings you can't put a price on.

I bought my first 124 in 1975 new. That one is long gone but I now have it's twin. Brings back fond memories everytime I drive it. Of course there are the not so fond memories every time it leaves me waiting for AAA on the side of the road.breaks

Hopefully with a well tuned modern EFI/ignition system the not so fond memories will fade into the distant past.
 
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