Planning M116.963 K-Jet to MS3 Upgrade

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Stashman94
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Joined: Mon Jun 19, 2017 8:30 pm

Planning M116.963 K-Jet to MS3 Upgrade

Post by Stashman94 »

I have a 1985 Mercedes 380SL that I've been mulling over converting from the K-Jetronic CIS to an MS3 or MS3X EFI to control both fuel and spark. I've been through a bunch of forums and videos to try to compile a list of all of the sensors I will need to add to get the MS system to work since my current setup has barely anything. I know that I will need a 36/1 crank trigger wheel and a crank position sensor to run the injection and I've seen that I will also need to install a cam position sensor (the crank on a 4 stroke engine moves twice as fast as the cam). The car currently has a distributor and I want to go full sequential distributorless and I was trying to think of a way to use the current distributor to make a cam sensor. Does anyone think that if I change the current gear on the distributor to one with twice as many teeth (should take twice as long to make one full revolution) that I could grind off all but one tooth of the reluctor so that a cam position sensor will know when cylinder 1 is at TDC? Feel free to tell me how dumb some mistake I've made in my thought process is, I wouldn't be surprised if it won't work.
DaveEFI
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Re: Planning M116.963 K-Jet to MS3 Upgrade

Post by DaveEFI »

Do don't need to alter distributor gearing. It already only turns once per engine cycle - half crank speed. The crank trigger wheel provides the accurate timing signal for the sparks etc - the cam position one only needs to tell MS which cycle the engine is on.

Assuming you're going to some form of multi coil system, a full dizzy with no plug leads might look odd. Many cut it down in size and remove the advance mechanism. The plate on the end of the shaft (that the advance springs go to) can then be re-shaped to a 'D' or whatever with a sensor on that. It will then be a single tooth wheel. Allegro make small gear tooth hall sensors that can be fitted inside most dizzys for this purpose.
Last edited by DaveEFI on Thu Jun 22, 2017 9:57 am, edited 1 time in total.
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Stashman94
MS/Extra Newbie
Posts: 3
Joined: Mon Jun 19, 2017 8:30 pm

Re: Planning M116.963 K-Jet to MS3 Upgrade

Post by Stashman94 »

That makes sense, I don't know why I thought it would spark twice like that.

I was planning on removing all vacuum that goes to the distributor then fabbing a smaller cap that doesn't have the plugs on top to try to make it look a bit better.

I found the allegro micro hall effect sensors, but would I need to build a board for this to go on? It doesn't look like most cam position sensors I've seen before.
DaveEFI
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Re: Planning M116.963 K-Jet to MS3 Upgrade

Post by DaveEFI »

Depends on your dizzy how easy it is to do, Here's one. The cover (not shown) is just flat ally plate with a badge glued to it for looks.

Image
Rover SD1 3.5 EFI
MS2 V3
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Tech Edge O2
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Stashman94
MS/Extra Newbie
Posts: 3
Joined: Mon Jun 19, 2017 8:30 pm

Re: Planning M116.963 K-Jet to MS3 Upgrade

Post by Stashman94 »

That looks so cool, thank you! I'm probably going to build just about the same exact thing, that should work perfectly.

And just to be 100% clear so I can't screw this up, I want the hall sensor to pick up the tooth when the number 1 cylinder is at TDC, correct?

Thank you for all of your help so far!
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