direct fire the trail
 

i direct fired the trail and it seems to hesitate. has this been done succesfully? i used 2 2nd gen coils, 1 for lead and 1 for trail/ help anyone?

it also is hard to start. use to start on first turn over, now it turns over, pauses like dead batt then turns over 2 or 3 times to start.

So you used two 2nd gen. leading coils? You can't do that on the trailing because the wasted spark will fire the incoming mixture due to the location of the spark plug in the housing. Your engine will not run properly and at worst it may cause damage.

The only easy way to run direct fire on the trailing is with an engine management computer.

REVHEAD is very right. You better put it back the way you found it before anyone else see's this :) Now you know why the second gen trailing coil looks funny eh?

Wasted spark style direct fire is a HUGE no,no on the trailing ignition as the guys said.The FC can get away with direct fire on its trailings because the CAS and computor work together to seperate the T1 and T2 signals,and direct fire each plug on its own.Thats why there are 2 seperate trailing coils and ignitors.The trailing is direct fire from the coils to the plugs,but they dont fire simultaneously like the leadings.

Firing both trailing plugs simultaneously will cause one plug to fire correctly on the power cycle and the other plug to fire at the middle of the compression cycle while air/fuel is still being draw in.Big damage can occur because the intake ports are still exposed and the mixture hasent been properly compressed.Get it back running through the distributor cap like it was,before you run it again.......

well i checked everything out and a loose wire caused the weird idle but she runs great. no backfire really. so this could be a bad set-up? i'll change if i have to but other than an occasional hard start she runs good.

i did this on my 1st motor....<---the reason im on my 2nd motor(its also killed my N rotors :( ... you are getting alot of pre-detonation witch is very very bad for apex seals... your best bet is to only do the mod to the leading and leave the trailing be..just put a good coil on it and/or a msd box

well i tried. i will switch it back now. thanks for all the info. i just figured whats good for one is good for the other. thats what i get for thinkin.

lol its all good i..was thinking the same thing when i did it...im like why dont more ppl do this....then boom and i was like lol i guess thats why

I found a way to direst fire leading and trailing at the same time without an ems and without a wast spark.

wy dont you tel us all abowt it

shhhhhhhhhh its a secret!

lol i wanna hear the secret.....

I bought a setup from a member that will do that. It has two pickups for the leading and two for the trailing. I think I got it from elmond and the pics of it are still in a thread somewhere.

That guy's dizzy mod didn't allow simultaneously fired leading. He used some parts from an '80 dizzy too.

If I had to choose between NON-simultaneously fired leading with direct fired trailing, as above, or true simultaneously fired leading with through-the-dizzy-cap fired trailing, I'd choose the latter every time. The former is not worth it IMHO.

I took a second gen cas, removed all but 4 equally spaced teeth off the bottom wheel realigned the top wheel (2 teeth opposing) with 2 of the teeth on the bottom. Then realigned the top pickup and added another on the top spaced at a 45 degree angle. One pickup on the bottom firing every 90 degrees ( jeff20b ther is your true simultaneously fired leading) and 2 on the top, each firing every 180.

how about for a 20b, one tooth wheel on the bottom firing the first rotor, one tooth on the top firing #2 at 120 past the first, extend the shaft build up 2 more levels and have a third level fire #3 and on the top level a one tooth wheel firing 3 sensor at 120 apart and lined up with it correlating sensor bellow. sounds like bs but it can be done. If it was done well you could actually make the top level maneuverable from left to right and get a trailing split.

mazdoo, that great, but where's your mechanical advance?

I'm working on that as we speak, however I am a Little in the dark as far as this process goes. Can someone explain how the mechanical advance should operate? For example - Idle to 1000 rpm = 15 degrees of advance ect ect. If i can get some ideal numbers I can integrate an advance.

How would you do that with a CAS? Theres no mechanism in it to allow any advance. I bought one years ago to do pretty much what you described but gave up after hitting that problem.

From what i gather advance should be greatest at idle ( but by haw much?) and at what rpm does it return to no advance? what would be the ideal curve? I've got a few ways to do ut just need some numbers.

I could do a 2 stage timing advance so that at idle it is x degrees and at a given rpm, change it to x degrees. this would be less difficult, however is a "curve more desirable?

Thats backwards except for a turbo engine. Those retard as rpms increase.

A curve is best. I think Id prefer no advance to a violent switchover during acceleration.

What about a combination of the two of them to get the best of both worlds?


https://www.rx7club.com/attachment.p...hmentid=120236

To get a wast spark in the second chamber run a 4 tooth whell on the bottom and stagger the top left sensor clockwise 45 and run that two tooth wheel on top.