Interest in custom distributor trigger?

[Hotrodpez]

I am planning to go with an SDS EM-4 6F. This obviously will require that I remove the dizzy and use crank trigger magnets. I was thinking of another distributor-less system I have used on several VW Type One engines. This system used a custom billet distributor "cap" that contained the sensor, and a "rotor" with the magnets in it that replaced the stock rotor. I was considering making a setup like this for the L engine... and then it occurred to me, why not replace the entire distributor with a custom unit that eliminated all mechanical and vacuum advance parts, as well as the distributor body with a small machined billet aluminum "trigger unit". I would probably use the stock distributor shaft. The advantage to this is it is a universal system that could be compatible with any fuel and ignition management system. It could even be constructed with two or more sensors (ex. one hall effect and one magnetic, for use with two separate systems). It would eliminate the need to mount crank pulley magnets or trigger wheels, as well as mounting the sensors. And it would be friggen cool! So all this considered, I could fab one up on my lathe, but that would take a while and it would be easier to do if I could design one up in 3D, and have it CNC machined. This will obviously increase the cost for a single one-off piece for me, but is there any interest in doing a small run of something like this? Or have I once again out-thunk myself and someone already makes this?

[woldson]

There has been discussion on how precise the measurements can be off the dizzy compared to crank.

That would be a cool idea, but why not edis and install the 36-1 at the crank. Seems this will be easier and alot cheaper.

[510six]

It sounds similar to the EPM that AEM makes that uses a similar optical sensor as those used in the Nissan CAS . Most aftermarket ECU`s are compatable with the Nissan CAS units in the 280zxt /300zxt distributors. A modified 1981 turbo dist. is used in my setup as a cam position sensor using a Ford VR sensor from a 2005 Mustang V6. It would have been nice not to have all the work of modifing the dampner to fit the trigger wheel and sensor.

 

http://www.aempower.com/ViewCategory.aspx?CategoryID=210

 

http://www.cardomain.com/ride/2071134/2

 

[TimZ]

There has been discussion on how precise the measurements can be off the dizzy compared to crank.

That would be a cool idea, but why not edis and install the 36-1 at the crank. Seems this will be easier and alot cheaper.

 

I was thing the same. However, this would be a great place for a cam position sensor to allow full sequential operation for those with the capability. I'm currently running a modified 280 dizzy to do just that and it works great. If you could do the same thing in a smaller package that might be interesting.

[woldson]

Now correct me if I'm wrong, TimZ, the problem with dizzy setup is the variances in the minute tolerances of the mechanics to the dizzy.

 

So setting up sequential fire would be, lets say, self defeating?

[Hotrodpez]

...variances in the minute tolerances of the mechanics to the dizzy.

 

This is what I was considering, and why I started thinking about making a fully custom unit with no advance or other mechanicals.

[ozconnection]

Now correct me if I'm wrong, TimZ, the problem with dizzy setup is the variances in the minute tolerances of the mechanics to the dizzy.

 

So setting up sequential fire would be, lets say, self defeating?

 

Isn't this the reason why we move altogether away from timing anything off the dizzy spindle?

 

My understanding of the situation is that to obtain the most accurate timing for anything, it was to be obtained from a crank angle sensor.

 

Isn't it to do with gear mesh, the required clearances and backlash as the drive spindle rides up and down and back and forth especially at rpm, like Woldson said?

 

As the parts wear, wouldn't the timing become less accurate? Would that happen with a crankfire setup?

[Doug71zt]

You won't be able to use a dizzy setup for the SDS system as the dizzy runs at half crank speed. I put my SDS magnets in the flywheel (my first setup had them in the crank pulley) and I am quite happy with the results. It is actually quite easy to work out a crank-trigger setup for the SDS in the flywheel.

[Six_Shooter]

Now correct me if I'm wrong, TimZ, the problem with dizzy setup is the variances in the minute tolerances of the mechanics to the dizzy.

 

So setting up sequential fire would be, lets say, self defeating?

 

 

No it's used to trigger each spark or ignition event, it is used to sync the ECM/injection/ignition to the engine. In most cases there is a single trigger event for one power stroke of one cylinder, in other words, there is a single trigger event for 720* of crank rotation. The dizzy rotates at half the engine RPM, and would use a single tooth, or notch to trigger this sync event. Not very difficult to get this set up to be accurate, since it's usually synced to cyl #1 TDC on the Compression stroke. In most systems it is only used at start up and when the RPM comes back down to a particular threshold where the ECM will revert back to sequential injector fire below a certain RPM.

 

This is the exact application I was thinking of for something like this.

 

For ignition triggering, the crank trigger wheel is best option, since there is no mechanical "slop" between the crank and the triggereing device like there would be with a dizzy replacement part.

[TimZ]

Now correct me if I'm wrong, TimZ, the problem with dizzy setup is the variances in the minute tolerances of the mechanics to the dizzy.

 

So setting up sequential fire would be, lets say, self defeating?

 

No - you still use the crank trigger for the actual timing events - since the dizzy already turns at half speed, it's a perfect candidate for a cam position sensor. Timing constraints for this signal are generally very loose - like you need a trigger anywhere from 5 to 60 degrees before TDC on #1 on the compression stroke.

[RTz]

Now correct me if I'm wrong, TimZ, the problem with dizzy setup is the variances in the minute tolerances of the mechanics to the dizzy.

 

 

I tested this scenario a while back. The result was not as bad I had expected... http://forums.hybridz.org/showpost.php?p=667353&postcount=26

 

 

So setting up sequential fire would be, lets say, self defeating?

 

Sequential is way more forgiving then that.

 

Without a doubt, crank trigger with a cam reference is one of the most accurate timing methods we can can easily achieve, but its not perfect. No engines crank is perfectly rigid and any flex will lead to some timing error... our long L cranks are no exception.

[gregkring]

I was thing the same. However, this would be a great place for a cam position sensor to allow full sequential operation for those with the capability. I'm currently running a modified 280 dizzy to do just that and it works great. If you could do the same thing in a smaller package that might be interesting.

 

 

Tim, here's my cam sensor setup for distributorless sequential injection. Very easy to make from a Buick turbo V-6 cam sensor. It is a Hall effect with a shutter window. Very small package as you can see. These sensors are getting harder to find, however.

 

 

 

 

I disassembled the shaft out of the middle, then cut the shaft down to the correct length as well as the aluminum shaft housing right below the oring. Then it was just a matter of using a freeze plug bushing on the datsun cover and cutting the slot in the sensor for the distributor drive.

[Careless]

that is a cool idea.

 

you people on this forum rock. LOL

[blairjj]

I agree idea is good, but looking up the price on Rock Auto scared me off...

 

GM part #25516915

 

AIRTEX Part # 5S1243 (Rock Auto part number) - $317.79

 

Ouch!

 

Jay

[gregkring]

I agree idea is good, but looking up the price on Rock Auto scared me off...

 

GM part #25516915

 

AIRTEX Part # 5S1243 (Rock Auto part number) - $317.79

 

Ouch!

 

Jay

 

 

Yeah, you do not want to buy new!

When I built this car 10 years ago there was no megasquirt, and very few other systems out there. I used a FAST computer designed for the Buick V-6 grand nationals. It allowed me to have a fully programmable MAP based sequential distributorless system with wideband feedback control. It helped that I also had a GN so plenty of spare parts. Back then the cam sensor could be had for $30.

Now they are plenty of other options out there. I just wanted to show how other things could be adapted to work for those of us without accesss to CNC machines.

[woldson]

I tested this scenario a while back. The result was not as bad I had expected... http://forums.hybridz.org/showpost.php?p=667353&postcount=26

 

 

 

 

Sequential is way more forgiving then that.

 

Without a doubt, crank trigger with a cam reference is one of the most accurate timing methods we can can easily achieve, but its not perfect. No engines crank is perfectly rigid and any flex will lead to some timing error... our long L cranks are no exception.

 

 

Got it:). I was just considering timing events at high rpm and figured that the window would narrow too far that small discrepancies could throw off injector timing. Or rather not give enough time.

 

Would not a belt driven cam be better than a chain for cam timing?

 

In any event, the avaliblity of edis parts and cost, plus the large amount of information here at HbridZ makes it a "no brainer" for the likes of myself.

[510six]

Got it:). I was just considering timing events at high rpm and figured that the window would narrow too far that small discrepancies could throw off injector timing. Or rather not give enough time.

 

Would not a belt driven cam be better than a chain for cam timing?

 

In any event, the avaliblity of edis parts and cost, plus the large amount of information here at HbridZ makes it a "no brainer" for the likes of myself.

 

At the time I was thinking of using the AEM EMS and using the Nissan CAS, a friend who was tuning Ken Carlson`s Bonneville 300zxtt was having timing errors with the CAS at high rpm. AEM`s solution was to fit a custom 24-1 trigger wheel in the CAS to eliminate timing errors( AEM has since corrected the problem and standard CAS wheels work fine now). I didn`t want the headache and since I was using an AEM for a OBD1 Honda with VR sensors and Ford EDIS sensors are also VR and later model Ford cam position sensors are VR and commonly avalable .

 

After some initial headaches and having to put some resitors on the AEM board and "modifing " the 36-1 EDIS wheel to a 12 tooth. The sequential injection with wasted spark ignition using an AEM CDI works great. It just would have been alot easier putting a 280/300zxt CAS on the car and triggering whatever coilpacks through the CDI, and the fact that the timing would not have quite as precise as a crank trigger would not have kept me up at night.

[Tony D]

We started having issues on the TEC2 unit using the Electramotive "Small" ring in the distributor once we exceeded 8500 rpms...just as Electramotive said we would.

 

For cam trigger, as TimZ says, the distributor is a perfect place for it...it's basically only 'return' signifying where #1 TDC is---and that window for tolerance is pretty wide. Basically any time before #2 in the firing order is ready.

 

I'd be shy of using the Dizzy for actual timing if you are considering higher revs. Our system was directly off the spindle, with a mag pickup through the vacuum advance hole reading the 60 toothed ring normally found on the crankshaft. The small diameter (from what EMotive explained) was the source of resolution errors in the processor at elevated engine speeds.

 

For a street engine it may be acceptable below 8000, though. We were fine to that range. Above that, however, we started having sensor errors in the firing, and I'm convinced it was due to the gear lash in the sensor letting the teeth 'rattle' as they rotated causing trigger errors.

[Hotrodpez]

So, Tony, as long as I plan to keep the RPM below 8000 (which I do, and I'm sure most other street-driven Zs do as well) then a distributor-gear driven pickup would be OK for both fuel and spark? And in this case, IF I were to try to make a few of these (or at least a few machined bodies, to help offset cost out of my pocket) I would have to try to find a place to do it cheap enough that someone could justify buying one for a street build. Otherwise, if I really want one bad enough, I'll just make it myself on my lathe out of some spare aluminum billet I have laying around.

[Tony D]

Ya know, JeffP once thought a 7000 rpm redline for his turbo motor 'would be more than enough'.....

 

Once these things get going, especially with a cam and some forged pistons it's suprising how high they will zing, especially in the lower couple of gears.

 

I would say 'yes' it should be O.K. But realize that the distinct possibility exists that the engine may be bumping against the upper limits of the design quicker than you may think.

 

Below 8500 the distributor setup for the TEC was rock solid and never gave us a problem. There may be the possibility that the 'old' system we had on that car may make it into something street-driven of mine simply because of the ease of retrofit.

Once we went above that limit as hinted to by EMotive in their manual, it got intermittent issues, and nothing we could ever trace down to anything other than that setup. It really depends on what your EMS calls for in the way of resolution.

 

I know 1FastZ found out about upper rpm limits really quickly with EFI...I think one of the first things I asked him after he fired off his Megasquirt System in the Silver car the first time was 'Do you have Forged Pistons in this?' Soon, he found out why... "They rev so easily!" LOL Plans are plans...sometimes your foot and your plans don't coincide and you find out 50mph+ in first gear pulling Lambos up an onramp is good sport! hehehehehe!

 

Hey, the appeal for a street driven car for a drop-in replacement is great. My wife's 260 has a 280ZXT CAS setup waiting to go into it for a MS-Se retrofit, more for a 'fuel only' upgrade really, but since I can drop-in a CAS and get Spark Command why not?