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Thread: Rotary ignition systems
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Klaus43
Rotorhead
Posts: 1259
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posted March 22, 2002 09:39 AM |
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...plugs not the problem!...
I've been successfully running BUR-series plugs in all 4 locations on my driver REPU for a couple'a years now and loving 'em! My ignition is still not DLDFIS, just the 1st gen electronic dizzzy...but these plugs last and last, and have good charactaristics thruout my usable RPM range--even tho on my japan-port motor power maxes out by 6K RPM... I just periodically clean & inspect 'em, and put 'em back in... they work great! (And outlast previous versions). Looking forward to trying this direct-fire setup with 'em, for sure!
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Jeff20B
Moderator
Posts: 661
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posted March 22, 2002 02:34 PM |
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I'll have to try the BUR plugs in mine! What heat numbers are you running? All 9?
His truck is using a 12A Nikki carb on a modified ('79?) manifold to fit it to a 6 port GSL-SE 13B. It may have a vacuum leak which causes the misfires. I'm not really going to mess with it anymore because he wants to get a supercharger for it. His Camden A/F guage says he's running too rich. Maybe it's a rich misfire condition?
The ignitor plate is already finished for my Cosmo. All I've got to do is drive it around a bunch before hooking up DLIDFIS so I can see if it made an improvement in the power. Gotta do a few other roadworthiness type things first though (don't want to get stranded). It sat for four years before I got it, then it has sat since '98 as a side project after I got it. I found the perfect spot for the ignitor plate. I just need to do a bunch of other stuff/cars before I can get to it. My bro recently backed out of wanting to get an engine for it (he made big plans, but then folded). That sucked. Maybe I'll keep it on the back burner for a little longer. At least the ignition is ready to go when the rest of the car is.
If I never get any other ignitors (heh, yeah right) I could use the Cosmo's currently unused one as the Trailing ignitor on my MG and the MSD as the Leading ignitor for both coils. That's why I mentioned it above. However, I'm not going to do what RX-Midget did and mount it down inside the fender. I'll need three ignitors to get this car running properly.
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'74 REPU
'76 Cosmo
'77 MG Midget 13B
'81 RX-7
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Klaus43
Rotorhead
Posts: 1259
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posted March 24, 2002 08:11 AM |
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...I'll have to look again...
...which heat #'s I'm using...I think they're all 8's, but I'm not even sure anymore...might run better w./ 9's...(?) They're all the same, anyhow. The reason I think they work so well & last is because of the huge amount of metal available for 'sidewires'...and the center electrode being so deep in there. Probably nullifies the 'plug position effects' we've observed due to the directional nature of the rotary's rapid-moving charge... (by that I mean the response at various RPM's being affected by the position of the sidewires--on two or three-wire plugs esp.-- as the plug happens to sit when torqued...) Also, I'm told the theory at least is that what does ignite 'deep inside' the BUR cavity then blasts outta there w./ a much bigger flame/ignition front...
Has anyone ever tried opening up those tiny ignition holes for the trailing plugs? Seems like that could be of benefit to racing/ peripheral port applications where the timing is radically altered from stock...
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Jeff20B
Moderator
Posts: 661
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posted March 24, 2002 08:53 PM |
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Hayes experimented with large Trailing holes. I'm not sure what the outcome was though.
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'74 REPU
'76 Cosmo
'77 MG Midget 13B
'81 RX-7
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rotarypwrd
Revvin Up
Posts: 55
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posted July 06, 2002 12:03 PM |
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Hey rotary family,
wasn't sure if this was addressed or asked yet, but I thought this would be a good a place as any. Rotary pro-pack ignition from Jacobs w/ rotary vehicles. Any good, bad, or ugly experiences?
Reason I'm asking: better gas mileage, performance, and more complete burn from an ignition system on a rotary.
thanks in advance for the info.
rotarypwrd
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Jeff20B
Moderator
Posts: 661
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posted July 06, 2002 11:44 PM |
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Well, I guess my whole point in all of this was to save money and use parts that I already had laying around, which also happened to give me better performance than the leading product commonly used on rotaries by the majority(MSD). There is all sorts of pro and con info out there. Infact, there is a current thread over at Mazspeed where a guy who really knows his electrics has hooked up an MSD and got bad performance from it. I'm not going to get into that here. Anyway, I've read lots in the various forums on the net that mention how expensive Jacob's system is. I have no desire to try it out.
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Uncle-Jim
Revvin Up
Posts: 64
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posted July 12, 2002 03:26 PM |
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Jacobs Ign.
I have a Jacobs on my 12A in the Rx-2. It is indeed a good system. The engine idles better and starts well. The main advantage is below 3000 rpm where the ign is doing multi-strike.
The disadvantage is the expense. For the cost of one unit, I could have got two MSD's. Bottom line, I don't think the Jacobs is worth the cost (on a rotary).
I know a guy at Hayes in Seattle who is doing the DLDFIS with an MSD firing both leading coils, and another firing the trailing through the distributor. He's really happy with it.
(Hayes thought the DLDFIS with the the stock ignitors was really clever, and are going to try it in their shop).
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Uncle Jim
72 Rx-2 Show Car; '77 REPU (250K & goin' strong) 2 - '76 Cosmo's
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Tom93R1
Redlining
Posts: 458
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posted July 15, 2002 02:16 PM |
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I have been wanting to do the DLIDFIS in my REPU but the wrecking yards in the Phoenix are seem to never have any rotary vehicles and I have not been able to get the extra coil and ignitor. Is there a decent, cheap coil and ignitor that anybody can recommend? Preferably something I might be able to pick up at Checker or Pep Boys? There shouldn't be a problem with mixing ignitors and coils as long as the 2 leading coils/ignitors match, right?
____________
'74 lawn-green
4-port 13b
Weber 48DCO
Racing Beat Header
Magnaflow
resonator/amplifier
really loud!
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Jeff20B
Moderator
Posts: 661
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posted July 16, 2002 12:34 AM |
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Right. You could buy a cheap alternative ignitor and coil and put them on Trailing so both J109 ignitors and regular coils can be on Leading. Maybe a GM HEI ignitor will work ok?
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Tom93R1
Redlining
Posts: 458
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posted July 23, 2002 11:18 AM |
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Hey Jeff, I was reading your write-up again and it isn't clear what wire you ended up using to get signal to the ignitors. You mention shielded headphone wire but you didn't know how well it stands up to the heat. Is that what you ended up using?
____________
'74 lawn-green
4-port 13b
Weber 48DCO
Racing Beat Header
Magnaflow
resonator/amplifier
really loud!
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Jeff20B
Moderator
Posts: 661
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posted July 23, 2002 10:16 PM |
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Nope. I'm still using the regular wires I started with. It turns out the slight misfires I was getting were just from an old NGK Trailing coil to cap wire. I swapped in a newer one and it runs fine again.
Jimbo and a few others used shielded wires with good results. I guess you can use whatever's handy. Just make sure to switch to shielded cable if nothing else solves your misfires, should you ever get any. By the way, my friend got brand new NGK wires and his engine now runs even better than it did before.
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Tom93R1
Redlining
Posts: 458
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posted July 27, 2002 05:23 PM |
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I did the DLIDFIS in my REPU today. Dosen't feel much faster but it somehow feels more powerful and definately idles more smoothly. I know the timing still isn't quite right and that I'm sure will help things. I kept putting it off during the week thinking it would be more work than it really was. After I finally got going it took about 2 hours including all the trips to Checker for more connectors and wires. Thanks for the cool idea and great instructions Jeff.
____________
'74 lawn-green
4-port 13b
Weber 48DCO
Racing Beat Header
Magnaflow
resonator/amplifier
really loud!
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Jeff20B
Moderator
Posts: 661
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posted July 28, 2002 12:03 AM |
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Cool man! I'm glad you got it working :) You gotta love that idle. Does it sound more like an '86 and later RX-7 now?
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Tom93R1
Redlining
Posts: 458
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posted July 28, 2002 12:58 PM |
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It is hard to say, that Weber carb is so loud I can't hear anything over it. All I know is that it does sound different than before. Maybe after I get an exhaust that is as loud as my intake...
____________
'74 lawn-green
4-port 13b
Weber 48DCO
Racing Beat Header
Magnaflow
resonator/amplifier
really loud!
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Jeff20B
Moderator
Posts: 661
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posted July 28, 2002 02:17 PM |
 Edited By: Jeff20B on 28 Jul 2002 14:21 |
A long time ago I noticed that old rotaries sounded different than newer ones. At first I thought it was due to different exhuast systems, but the evidence kept proving otherwise. It turned out to be the dual Leading sparks of all the '86 and later RX-7 ignition systems that was causing it. None of the older stock pre '85 engines sounded that way. All the DLIDFIS, SLIDIFS, MSD DFIS, and stock '86+ wasted spark ignition systems that I've ever heard don't sound like any 6 cylinder engines that I'm familier with either, that's for sure. I think the rotary engine sounds unique unto itself with wasted spark ignition and without. I think the pre '85 rotary ignitions cause the engines to sound more put-put-put-ish (like 4 cylinders, yuck). That's why I prefer the '86 and later sound.
By the way, I've never heard a 20B with wasted sparks. Only single firing Leading and Trailing with or without the L/T split. I'm curious to hear a 20B with wasted sparks but so far nobody has ever done wasted spark on a 20B... yet. The 20B sounds so cool already (the best exhaust note ever!). I wonder if wasted sparks would change the tonal characteristics of a 20B like they do with a 12A or 13B?
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bcrx7
1st Gear
Posts: 11
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posted July 30, 2002 08:09 PM |
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Jeff20B
Moderator
Posts: 661
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posted July 30, 2002 10:45 PM |
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Cool man! Good luck!
I just rebuilt a GSL-SE dizzy today. It needed some serious lubing because it came out of an engine that had nearly 200,000 miles on it. It's going on my truck's engine because it came out of a 13B so I'm going to try it on another 13B. I've tried it before but the advance action was so slow that it was kinda weird to drive on. The reluctor was also miss-cut so I replaced it from a known good 12A reluctor (you could see it in the timing light). I've got plans for the funky reluctor.
I'll be rebuilding another GSL-SE dizzy tomorrow. It's fun to screw with this stuff, you know?
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Tom93R1
Redlining
Posts: 458
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posted July 30, 2002 10:50 PM |
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What is a reluctor and how do you see it in the timing light?
How much of a difference is there between a GSL-se dizzy and one from a 12a? When I put the electronic ignition in my truck I looked forever for a GSL-se but after asking around came to the conclusion that a 12a distributor would work just as well for my 13b.
____________
'74 lawn-green
4-port 13b
Weber 48DCO
Racing Beat Header
Magnaflow
resonator/amplifier
really loud!
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Jeff20B
Moderator
Posts: 661
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posted July 31, 2002 10:59 AM |
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A reluctor is the little soft iron thing that sits under the rotor of the distributor shaft. It's held in place with a small rollpin. The shaft spins counterclockwise and you will notice that the cuts on the reluctor cause a slow rise time, then it peaks followed by a sharp drop off. This changes the ambient magnetic flux on the core of the pickup coil. The pickup coil is wound around a steel core that curves over and is riveted to a magnet with copper rivets. What happenes when you move a magnetic field inside of a coil of wire? It induces a voltage in the coil. The ignitor takes this 'trigger' signal and switches 12V on and off at the main coil (you know, the one that sparks the plugs).
Uh, got a little sidetracked there. The difference between a GSL-SE dizzy and the 12A kind is how much advance there is and when it occurs at a certain RPM. As far as I know, and what my timing light has told me, 12A dizzies have 20º of total advance and 13B dizzies have 25º total advance. I've been using 12A dizzies in my 13Bs for years, and I'm not sure if they're absolutely necessary. However, other people will tell you that if they have a choice, they'd rather use a 13B dizzy on their engines (13Bs). All I'm doing is taking what they said and using it to my advantage since I have access to SE dizzies. I'll see if the extra advance is usefull
I think I may take a picture of the difference between 12A and 13B dizzies today. Man, this other GSL-SE dizzy of mine must have been on an engine that was left in the rain because it's all rusty inside. I hope I can use its advance weights, springs, and upper shaft on a known good 12A dizzy. I hope the weight and spring attachment points are the same.
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Jeff20B
Moderator
Posts: 661
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posted July 31, 2002 11:07 AM |
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By the way, you can't see a reluctor with a timing light unless you don't have a cap on your dizzy. What I meant was using a timing light aimed at the timing marks on your pulley. You can see how accurate they cut that reluctor by how steady the marks are. If there was an error, you'll see it as a wavering of the timing mark(s). It will make you think you've got a bent dizzy shaft or something. My bro's GSL-SE dizzy did this, so I'm assuming it was caused soley by the reluctor and nothing else. I swapped reluctors, but I'll only know for sure after I install it on an engine and and use a timing light. We'll see...
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