mazdoo

Found a way to fire both the leading and trailing plugs simultaneously without ems or wast spark. I'll draw something up to post. Very simple!

peejay

I know that an Accel 300+ box will not do this.

I'll keep running it (leading-only right now) but eventually I will get another MSD 6AL and run three Blaster coils.

mazdoo

What I did was I took a second gen crank angle sensor and modified the stock signal wheels. In stock form the bottom wheel has 24 teeth and the top has 2. I removed all the teeth on the bottom wheel except for two opposing teeth and on the top wheel I left it stock. You will have to remove the gears (wheels) with a press to re-align them. When reassembling stagger the top and bottom wheel so looking down you have a tooth every 90 degrees. you now have a dedicated timing wheel for each housing with no split for leading or trailing. what you end up with is just like the direct fire dizzy setups but because each wheel fires its own housing you don't get a wast spark bla bla bla.... anyway just a quick and not very well put together explanation.

RETed

How do you control advance and retard?


-Ted

mazdoo

The cas does have as much play in the cas mount as a dizzy does so turn it as you would a dizzy. The triggers will offset one way or the other as you turn to retard of advance. However the timing wont be able to advanced via vacuum.

mazdoo

just seems this way you could run 4 ignitors and 4 coils one for each plug.
or 2 ignitors and 4 coils
Either way you get rid of that big **** dizzy!!!!!

mazdoo

If you left 4 teeth on the bottom wheel at every 90 and ran just the bottom wheel you could run both leading plugs with a wast spark and furthermore if you wanted an offset for the trailing you could direct fir each trailing individually by installing the 2 tooth wheel back on top and offset the trailing (top) wheel whatever degree split from the correlating bottom tooth. this system works and the cas will fire j109 ignitors.

rotarygod

iTrader: (1)

Have you actually wired this up this way and got it to actually work? I just don't see how it will function on the trailing. It will work on the leading side easily but you can not fire wasted spark on the trailing and this arrangement would appear to be doing so. Remember the CAS turns at half the speed of the engine. Also how are you actually controlling timing? You can only set it to one spot this way which would prefereably be full advance. You also can not adjust the timing split. It would always be fixed at whatever the teeth offset between the top and bottom pickup wheels. I just don't see this being beneficial from a street car standpoint.

mazdoo

Correct me if I am wrong, the cas and distributor are geared the same way and spin at the same rate. Working off the way a dizzy operates it has 2 pickups and a 4 point gear. the leading pickup will fire 4 times per one full rotation of the dizzy. When doing a direct fire leading mod you take the leading ignitor and run it into 2 coils, one for the front housing leading and on for the rear housing leading. As the 4 pin whell spins stating on 1rst housing leading spark (power cycle) it also fires a wast spark from the second coil into the second rotor (exhaust cycle) this seems to happen 4 times per 1 rotation of the dizzy or cas. The second pickup is the same just offset for the trailing split. The problem of trailing timing is run through the cap to split up and time the fireing of the trailing plugs. This is done because you need a way to separate the trailing plug firing order and are only getting one signal from the trailing pickup. As on a dizzy the both pickups are working off the same wheel and you have no choice in the fact that when the leading pickup fire you will get a trailing following it on the opposite side. With the cas the wheels are located one on top of the other, so when a leading pickup fires with a duel 2 tooth setup you can use that signal to fire 2 j109 to 2 coils, one for the leading and one for the trailing of that housing at the same time without signaling the other rotor.

peejay

In my experience, vacuum advance is critical for good drivability, part-throttle power, and fuel economy.

Of course, if you'd prefer to drive something that drinks fuel for no reason and feels like a soggy dog to drive, then be my guest.

mazdoo

"Of course, if you'd prefer to drive something that drinks fuel for no reason and feels like a soggy dog to drive, then be my guest."

So, no vacuum advance for timing = gas drinking soggy dog?
so everyone who runs a dizzy uses the vacuum advance?

mazdoo

what if there was a way to fire leading + wast and a trailing split from a cas in a direct fire setup. Would that be something worth doing

peejay

No, a lot of people don't. A lot of people think that sub-20mpg and poor off-idle throttle response is normal, too. Which is a damned shame, since they could really liven things up with a vacuum hose.

Oh, I forgot, underhood vacuum hoses = bad. Much better to cut fuel economy almost in half and have to rev to 3k just to keep up with traffic than risk having a vacuum hose under the hood...

mazdoo

peejay, don't get me wrong, I'm just asking q's as i would like to learn the adv - dis adv of advancing the timing. I am going to run this motor in a boat and therefore somewhat of a different story than street use. what would the engines characteristics be if i ran leading and trailing simultaneously each off its own coil and ignitor with no vacuum advance or wast spark?

mazdoo

if you could control all aspects of an ignition system at any given rpm including leading and trailing, split, wast spark or not and timing how would you build it for a 13b na carbed?
ie
no wast spark
0-1000 rpm full advance & 10 degree trailing split
1000 - max rpm no split ...

peejay

Ah, for a boat, I could not tell you. My experience is wholly with cars.

My instinct tells me that low RPM throttle response is not such a big deal since you don't have a "solid" load on the engine like you do with a car.

OTOH, one of the biggest tuning nightmares I ever had to deal with was an airboat, which is not the same thing (unless you have a 7-foot six-bladed prop ) but my preconceptions were proven to be horribly wrong.

rotarygod

iTrader: (1)

I'm not sure I follow exactly how you're talking about setting it up. Are you talking about using 1 pickup wheel for each rotor and then firing the leading and trailing on that rotor at the same time?

t_g_farrell

iTrader: (1)

Why is it a good thing to get rid of the wasted spark? Its not really wasted (it should be called extra spark), it helps fully burn the charge at the end of combustion. At least thats my understanding and that helps clean up emssions, smooth out the idle and increase fuel economy slightly.

Not dissing your idea, sounds kind of interesting. Using modified 2nd gen signal wheels and the cas without a computer being required so we can get rid of the distributor and get a more reliable solution could be worth the effort. Especially if the timing adjustments can either be easily modified or nailed down easily at the installation. I'm not real familiar with the CAS part though.

Can you get pictures of this setup that walk us through the whole thing? That would be cool.

mazdoo

I'm not sure the wasted spark helps burn anything, the trailing spark does. I could be wrong about that but the wasted spark does have its loyal followers. I am interested in knowing what effect it has, I think jeff20b has some ideas about that.
A good link to view leading, trailing and wast sparks. Notice the wast spark firing in the exhaust phase of the rotation.
http://www.rotaryengineillustrated.c...quicktime.html

Judge Ito

This is a great idea. So many racers are using electronic distributors and run into all kinds of high rpm problems. Especially the dizzy rotor shattering into pieces @ an over 10,000 rpms. With this set-up there is no centrifugal timing advance, but still a gread idea. I have seen an done this in the past. Running no timing split between trail and leading. I had the the upper gear machined with a small allen bolt to allow me to easily adjust timing. I later wanted a timing split and went to the old style dizzy with a wasted spark(alot easier to do) and works well. on everey single race application, we eliminate centrifugal timing advance.

all this set-up needs, is a timing split between trail and lead. run 3 pick up coils. 1 for leading with a wasted spark. and find a way to run trail 1 and trail 2 without a waste spark and allow the tuner to adjust the split. mazdoo keep it coming. I seen your pics at nopistons. your very close..

mazdoo

Ito, this is a picture of the setup you would like, this is how i have decided to go. The cut away cas shows the customized bottom and top pickups The bottom is for leading 1 & 2 fired every 90 degrees by the bottom 4 tooth wheel. This gives you a wasted spark leading. The top pickup directly above it is the T1 pickup and you can see the T2 pickup on the second pic in the 9 o'clock position. The two top pickups are controlled by a 2 tooth wheel on top that you can offset from no split to X split of your choice by offsetting the top gear as desired. this is a direct fire leading and direct fire trailing cas setup with adjustable split. So the only down side to this is timing. easy fix!!!! Tell me what you think about this, take this setup with no advance on trailing add an msd 8981 programmable timing computer to the leading pickup before the 2 j109's. I haven't worked out the best numbers but for the sake of description we will lock cas at 20 degrees, this means trailing will always be a 20 degree advance. you can program the 8981 to retard the timing start and idle lets say 10 degrees. so at idle you are running at 10 deg. with a 10 degree trailing split. program the timing curve you want, when you curve ends it will be caught up to the trailing at max advance with no split. Again the numbers are just for example but the way to be able to do it is that.

rotarygod

iTrader: (1)

I see that you added a 3rd pickup to the cas. Now it's starting to make sense to me. I couldn't understand how you were trying to make it work with only 2 pickups. You aren't.

Judge Ito

mazdoo.. is the upper pic up coil for traling 1 secured? I mean for high rpms? that is the way to go.. great job.. if on some applications timing advance is needed, you could always add an msd dis ignition box or an haltech IG5 for timing advances

mazdoo

The mounting plate for the top pickup (T1) is welded to the bottom pickups mounting plate, so it's not moving at all.