Lynn E. Hanover

In a question about an ignition system for a 4 rotor, I offered that it would be quite simple. A crank trigger gets the job done with the very best timing accuracy, and the system is very cheap to build.



This was in a Mazda powered GTU (IMSA) under two point five litre car. It started out as the prototype for all Lola formula atlantic cars. At the time it wasn't worth much. Had I not cut it up for parts it would now be worth more than my house.



Later I added it to a first generation GT-2 with a Pport engine. I had the leads from the pickups running through a piece of braided cover teflon hose in order to protect them from the high energy of the secondary voltages. I twisted the pickup leads in different directions so they wouldn't cross fire by inducing voltage in each other.



It didn't work. It crossfired and broke the front iron through the dowel hole.



But it did work in the Lola when I just kept the pickup wires well away from each other.



So, if you have not gone to sleep, here is one way to build a crank trigger system.



I used an early RX-2 crank pulley. It was smaller than the rest of the pulleys bolted to the front of it. It hase two sheaves. The 4 bolt holes are handy to bolt on a Mr. Gasket degree wheel.



I made an aluminum disc a bit larger than the degree wheel. With a spigot to locate it in the center of the stock cast iron pulley. And bolt it on using the original bolts. The disc is installed on the pulley and the pully is marked for a single reluctor.



For mine I used a smooth shank 1/4 bolt. With a hydraulic press, I inserted the bolt into the edge of the disc and pressed it into place.



I cut off the excess bolt and trimmed the disc in a lathe untill about 1/3 of the bolt was visible.



Two magnetic biased distributor pickups from a 70s Chrysler product are installed on made up plates on the sides of the engine, so that the pickups are within .030" of the surface of the trigger wheel. The pickups are moved up and down on the bracket to alter timing. Wires from the pickups can go into a Chrysler product amplifier. Any parts store has them . The real expensive one is an MSD. There are two other models. One with 5 pins and one with 4 pins. You need a biasing resister to run the Chrysler amplifiers. About 5 bucks. Better yet, trigger an MSD with each pickup.



The output of the amplifier goes to a double ended coil from an Oldsmobile. One wire from each end goes to a leading and a trailing plug for one rotor housing.



Here is a picture of the poor old RX-2 front pulley. The picture is captioned.



Lynn E. Hanover

Lynn E. Hanover

Here is the front of the same pulley/disc. The timing marks are on both sides of the disc, (TDC and BDC) because you have to clip your timing light onto the number two rotor housing ignition leads and check that timing also. TDC for number two is at BDC.



Sorry about the dirt and rust. This piece has not been run in years.





Lynn E. Hanover

Jeff20B

Your accent is a little different than what I'm used to, but I was still able to follow your posts at least 90%. That's cool that you made it work. I had an idea like that a couple years ago, but settled on modding the distributor instead, for my 0/180º 20B ignition.



So how do you think a spark 90º after TDC would work?

banzaitoyota

You cut up a LOLA?

bill shurvinton

The crank trigger bit is good. The wasted spark coil is not really a good way to get fire into a rotor. The reason is that, in normal operation you have one end of the coil firing into exhaust gasses. These are highly ionised and so look like a near short to the plug. So you only get a little 'pop' at that end, and a big bang at the end you want to fire. If you are firing both sides of the coil into 1 chamber, then you will get 2 small bangs, which will not guarantee good ignition.



I'm building a 4 rotor ignition system at the moment. I must admit to having wimped out on one area and bought an autronic 4-channel CDI. The reason was mainly for risk reduction. I could have grafted a load of igntors together to get sufficient current drive, but the systems issues (40 odd amps needed to supply them for starts) made me decide to put that on one side for further experimentation. So the total cost is running around $500 but for that I get a fully 3D mappable igntion that will ignite almost anymixture, of which 300 is the CDI box.

Lynn E. Hanover

Yes, I cut up a Lola. But first we converted it to a single seat CanAm car.



Then we cut it up and made the second IMSA GT under car out of the running gear.



It was black with gull wing doors. I narrowed a Chevron nose. Made up all of the body molds etc. FT200 Hewland, two seats, right hand drive, tube frame and of course a rotary engine. I ran it in A sports Racing in SCCA. It got some wins even.



A collector has that car now. It is still in central Ohio.



You get old, you get smart.



No way around it.



Lynn E. Hanover

Lynn E. Hanover

Well,



If you have one MSD 6T driving each double ended coil, rest assured the either end of that coil can weld you watch to your arm, and make you sit in the grass for a while trying to remember your name. An arc will jump from the back end of the sparkplug boot even though the engine is running and the plug is firing.



Here is a tip that can save you some pain. An MSD fires once when you turn on the ignition switch. If you have been screwing with the fuel supply, and there is a bunch of fuel in the exhaust system, the explosion can just about knock it off the jack stands, and open a closed garage door.



I ran it with just the Chrysler amplifiers and no MSD, and it works fine up to 9,000

RPM. That was all the RPM we ran back then.



The MSD runs the coil at 350 volts, so some coils will not stand up to the job without overheating. MSD has a list of coils to use. And makes an style of coil you might want.



Lynn E. Hanover

Lynn E. Hanover

I could not remember where the apex seal is at 90 degrees, so I ran out to the shop and stuck a degree wheel on a front plate, rotor and housing.



At 90 degrees the apex seal is less than 8 degrees from uncovering the trailing plug hole. That hole has a recessed plug and a cavity in front of the plug.



I would worry about any residual burning fuel in this cavity could set off the next charge. Just one of those can break the cast iron. I wouldn't do it.



Lynn E. Hanover

DJ Rotor

This is good stuff. Someone sticky it



J

j9fd3s

i ran a dual coil setup on my 3 rotor street car (triggered by the stock cas and an ecu) i always had problems with the spark being weak, i now have individual coils and its much better. it might be that the gm coils are much better than what i used, i had fd coils