Bigretardhead

hi. I actually have a FC, and am running megasquirt on it (or trying to), and am thinking about going with a gsl-se distributor setup instead of the stock distributorless setup really just for an easier setup, and to eliminate the stock computer completely...

the thing though, is, I'm unsure of how the distibutor works to perform the timing split between the trailing and leading plugs... I remember hearing of people just running 0 split, but that was only on n/a cars, and apparently its not good for turbo motors...

if anyone has any info for me on this distributor that would be great... and this is in the correct section, right? (since this is about a 1st gen rx7 part...)

thanks. oh, and I tried searching, but after two pages found nothing.

mwatson184

Leading timing is set by turning the distributor...easy enough.

The L/T split can be adjusted by unscrewing the 2 screws on the trailing vacuum diaphram sliding it in or out.

-Marques

gsl-se addict

iTrader: (3)

Yes, this is the right section. You actually, don't have to limit yourself to the GSL-SE distributor (they are harder to find, only made 2 years, most expensive model). Any '81-'85 distributor will to the job. The only difference between the 12A cars and the 13B (GSL-SE) is a slightly different advance curve. The 12A distributor will work fine on the 13B (that is what is on my GSL-SE right now).

Here is what the advance curves look like for the 12A and 13B distributors:



There is an adjustment on the distributor that lets you change the trailing in relation to the leading (split). You don't really want to go with a zero split. Maybe others will go into the details. You can search for some recomendations on the split, but I think about 8-10 degrees is pretty common.

BTW: I have a MS as well. The car will run on it (used a connector so that I can easily swap between stock ECU and the MS), but not very well at the moment. I have been so busy finishing up with grad school that I haven't had time to tune it.


Hope this helps.

Kent

mwatson184

I've seen those graphs many times and never have agreed with them. They suggest full mechanical advance at around 1100 engine RPM...that is BS. It has been tested that the dizzy mechanically advances well beyond 3000 RPM. That is why many set their timing at 4000 RPM.

Well now that I think about it, perhaps the RPM axis is mislabeled. The distributor spins at half the speed of the motor, therefore the engine RPM should be double the dizzy RPM...They have it labeled as half. So what says 1000 engine RPM should say 4000, anybody agree with my reasoning?

The vac advance chart looks about right though.

-Marques

Bigretardhead

yes, that helps very much. thank you!

but, now... how will the vac advance work with boost?

IanS

iTrader: (4)

You need to "lock" the distibutor so that it will not advance centrifigally (sp). Also by leaving the vac advance uh "thingies" open there will be no vac advance. I am sure someone will post a pic, but if not I will later. I also have an extra dizzy if you are interested. I think the front cover or iron will also be needed but that could be wrong.

gsl-se addict

iTrader: (3)

Yes, I believe that it is mislabeled. It is showing that the engine rpm is 1/2 of the dizzy rpm, but if I am not mistaken, it is the other way around. Meaning 2000 dizzy rpm = 4000 engine rpm (full mechanical advance).

And yes, if you are going to run boost, most people disconnect the vac advance and lock the mechanical advance at full advance. So the timing that you will have will be fixed for all rpm/engine loads.

The other option is to us the MS ignition and only fire the leading plugs. The trailing plugs account for very little power and are mainly there to clean up emissions. This way, when the MS has the full ability to do leading and trailing, it will be easy to adapt and you will also have the advantage of being able to change the amount of advance depending on amount of vac/boost and with regards to engine rpm.

Kent

Bigretardhead

um...I hope not... I need my front cover to suplly oil to the turbo.

umm... anyone know more about this?
oh, and IanS, I might just hit you up about that dizzy.

thanks for all the info guys/gals?. greatly appreciated.

13B4port

i few things that you should rememeber. the 2nd crank angle sensor cause the leading plugs the fire a great number of times more than the 1gens. this gives you greater spark and more complete burn. you'll be loosing that. you may want to look into a MSD 6a for the leading plugs. Also your ignition needs to retard with the ammount of boost you put in the motor as well otherwise you get detonation. if you're only running 6-8psi then you can just retard the time right off the bat and disable the mechanical advance and vacum advance that the dizzys have. Or you could do something like what i did, i was getting up set about the loss of low end because of the locked dizzy having to be set retarded. i bought 2 MSD boost retarding modules and used 2nd gen crank angle and 2nd gen coils. these things allow you to adjust 1- 3 degrees per 1 psi. it works very well and also allows you to adjust the split.

another way you could go is MS is now offering ignition contorl. however it can only run one coil pack, so i wuld setup for MS to run your leading with a MSD 6a box and say screw the trailing. the MS will advance and retard the timing with boost and lo revs. it would probably be cheaper. from what i hear it works pretty well.

And the easiest solution would be to buy a 12at dizzy. very hard to find. but it would work great and would just drop in.

hope that helps.