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Discussion Starter #1
Hello- long time reader, recent poster here.
I am researching an alternative to the trigger points for D-Jet cars (I own 2) and I need a sacrificial dizzy for research and development. I am primarily interested in M116-M117 units due to the exorbitant cost of the trigger points from Bosch or Mercedes Benz, but I assume there are other makes and models that may be in a similar $$$ situation. I cannot promise that the end result will be any cheaper, but the whole point is that the end result will eliminate a very expensive wear item. The conversion will be designed to be visually undetectable.
What I require is a complete dizzy with trigger points. While the trigger points don't have to be new, or even work, they cannot be modified ("adjusted"); the base cannot be distorted. Also, the dizzy cannot have wobble. I can deal with shaft end play.
I am located near downtown Los Angeles, so ideally someone may have one close by.
As an incentive for someone who has a decent unit they are reluctant to part with, I can offer the finished tested product at my cost to them, with free installation, on the unit they provide. I will not be responsible for running issues related to other defective components, bad tuning, etc.
This may take awhile, up to a year or more even, and it may come to nothing, such is the case with experimentation. Nothing will be harmed or destroyed so the unit will be returned in same condition as received (well, maybe in better condition if I have to shim the end play).
Any interested parties please pm me.
 

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85 Audi Coupe Quattro, 85 Audi Coupe GT, 71 BMW turbo 2002, 73 BMW 2002tii, 85 BMW 635csi
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How are you going to make injectors 'fire'?
 

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73 280SE 4.5, 71 300SEL, 03 BMW Z4, 72 Fiat 850, 80 Triumph TR7, 85 Porsche 911
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Have you given any thought to pulling one from a junk yard? Finding a distributor with functional or otherwise trigger points shouldn't be too awfully tough. Many of the pick apart yards subscribe to a data sharing network, where a request for parts in Hawaii could be answered by a junk yard in Texas ...
 

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This is interesting. Unfortunately the D-jet system also suffers from other expensive parts failure such as the MAP sensor and the wiring harness that becomes brittle. Sorting out the trigger points may only lead to the two other problems at a later stage.

On the other hand the D-jet system is the easiest to convert to a Megasquirt simple version (MS2, fuel only, batch firing) as all the hardware can be reused nearly as is. Why not consider a more global solution?

I would consider replacing the whole dizzy by a later induction system dizzy as the one found on the early K-jet equipped cars. The signal of the dizzy would be used to trigger the Megasquirt. This would delete the trigger points completely as well as the cold start valve and replace the expensive D-jet MAP sensor with the one embedded in the Megasquirt controller. The old harness could be modified but given that they are most of the time very brittle making a new one would be best. All the rest of the D-jest system can be reused including water and air temp sensors. Quite an easy conversion, for less than the cost of an new D-jet MAP sensor, or trigger points if ever available. I did it myself, but I went EDIS ignition also controlled by Megasquirt. This is one step further for much more powerful ignition. Not necessary on a stock engine really.
 

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Discussion Starter #6
Hi GGR: Let me just say that your coupe is pretty cool! I missed one here in LA but one day...

I agree with you completely on this. Allow me to explain:

I have two D-Jet 107s. One will ultimately get the Megasquirt system, along with other tweaks. The other is a barn find car that I would like to keep original. I want to develop this idea for those who want to keep their cars as original as possible. With parts prices being what they are there is certainly room for alternatives and substitutions, especially if they look and operate the same, yet are cheaper and more reliable. BTW trigger points are available here. They list at over $900.00 at my local dealer, and over $500.00 through Bosch dealers. That leaves room for an alternative. It seems the trigger point issue is relevant to other makes, Porsche and VW being two (well, one now). I figure I will start there.

You predicted my next step, which is recreating visually correct D-Jet harnesses using higher quality materials. Aside from the MAP sensor, it seems that this accounts for the vast majority of problems with these cars.

I will also do this with the Megasquirt kit, possibly offering a visually correct plug and play system for those desiring such a thing. By its very nature Megasquirt appeals mainly to serious tinkerers, while others are put off by the unoriginal look. I would offer a kit in various popular configurations that addresses these issues. My primary concern is looking original. I am keeping the dizzy and running a dummy MAP sensor for appearances sake.

Perhaps if there is enough interest in the Megasquirt I will develop it first.
Any interest out there?
 

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64' 220SEc, 72' 300SEL 6.3, lots of parts
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Mega decision

This is good,
After I assemble the 4.5 motor for the 300SEL,
new bearings, rings, valve job and chain system and chain ears.
I may be wishing to convert to Megasquirt.

More details please ,
Should I keep cams stock or more low end torque or go for econo grind?
Will mega deliver better fuel economy?

This is to be a daily freeway and grocery flier.
these 4.5 SEL things suffer mileage at the stop and go routine,
Will not be run much over 70-80 max
 

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This is good,
After I assemble the 4.5 motor for the 300SEL,
new bearings, rings, valve job and chain system and chain ears.
I may be wishing to convert to Megasquirt.

More details please ,
Should I keep cams stock or more low end torque or go for econo grind?
Will mega deliver better fuel economy?

This is to be a daily freeway and grocery flier.
these 4.5 SEL things suffer mileage at the stop and go routine,
Will not be run much over 70-80 max
A well sorted megasquirt may help you save a bit of gas compared to the D-jet, mainly because your D-jet components are old by now and because Megasquirt allows you to tune the engine much more precisely.

But the stock US 4.5 engine is not the right one to start with if you're after fuel savings. The compression ratio is low, 8:1 or somethink like that, it is heavy and I'm not sure the cam grind is ideal as it was designed at the beginning of the smog regulations.

You should consider sourcing an early euro 500 engine. 100lb lighter and 9:1 CR. You would already have a better ignition and you could transfer the 4.5 intake manifold and D-jet hardware like I did.
 

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Discussion Starter #11
A well sorted megasquirt may help you save a bit of gas compared to the D-jet, mainly because your D-jet components are old by now and because Megasquirt allows you to tune the engine much more precisely.

But the stock US 4.5 engine is not the right one to start with if you're after fuel savings. The compression ratio is low, 8:1 or somethink like that, it is heavy and I'm not sure the cam grind is ideal as it was designed at the beginning of the smog regulations.

You should consider sourcing an early euro 500 engine. 100lb lighter and 9:1 CR. You would already have a better ignition and you could transfer the 4.5 intake manifold and D-jet hardware like I did.
GGR- Was that early 5.0 in anything besides the 450SLC? i.e. a 500SE?

Also; GGR, I know you have seen this already, but FWIW there is a chap on peachparts called Tony H who is figuring out how to stroke a 4.5 to approximately 5.0 using stock parts (560 crank and rods and machined 4.5 K-Jet pistons) that puts the crown of the piston at the top of the bore where it belongs rather than several mm down (EVERYBODY did this for emissions purposes in the seventies.) If it actually works it would mean a reasonably high 9.5 to 1 static compression ratio (the pistons are reverse dome) along with something resembling proper quench, effecting a more efficient burn that would be somewhat detonation resistant. A compression increase would allow for more cam timing, which a megasquirt system can take advantage of. This could be another option for people with early cars.
You can follow his progress here: m117 4.5 block measurement - PeachParts Mercedes ShopForum
and here:
Project: Iron block 5.0 - PeachParts Mercedes ShopForum
 

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Any Gen I euro 5.0 will do. They were found on the r107 SL/C and the W126 series. Quite a few made it in the US on the gray Market. Any 560 engine, euro or not, would also do as they were 9:1 CR. But then a Gen 1 ignition system should be sourced.

Yes, I'm following Tony's project. I find it quite an interesting exercise, though I prefer the later alloy blocks as they are lighter and keep the car better balanced. It's also less work as the long blocks are kept stock.
 

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5.0 progress

Glad to see someone is interested in my project. I agree a alloy 5.0 would be much less work and lighter but it is a rare engine and to find a known history, good engine would take a bit of searching. This way I will have a drop in, duplicatable, engine that uses common parts and the piece of mind knowing what's inside. The only real extra cost to this engine over a quality stock rebuild is balancing(+- $250) since I'm machining the pistons my self.
 
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