Another '81 Thread! (Tony, feel free to post, lol)

[badjuju]

After reading for about 5 hours, I've come to a couple solutions for my need for an MS setup.

 

1. Just MS.

Get an msd box for ignition, run MS for fuel, and go with an 82-83 dizzy

 

2. MSnS

Get an 82-83 dizzy, run MSnS

OR

Modify the CAS on my dizzy, run MSnS.

 

About right?

[Phyxius]

I don't know why, but I've been able to run my 81 cas for quite a while now without the advance restrictions that others have run into. I've been running with a trigger angle of 76 degrees with the timing dead on at idle.

[Tony D]

I don't know why, but I've been able to run my 81 cas for quite a while now without the advance restrictions that others have run into. I've been running with a trigger angle of 76 degrees with the timing dead on at idle.

Exactly how did you set yours up? i ran my car to the "Full Advanced" position as limited by the bracket, and when checking the timing with a separate timing light, I would only get around 30-32 degrees total advance. The car would run fine under boost but off boost the thing was soggy (compared to now!)

 

It will RUN, but I simply could not get full advance for high vacuum or cruise bins.

 

I will have to look at the 81ZXT motor I just pulled out. You can set it on TDC, and then check the teeth to see what kind of total advance you can physically get. If I recall, the stock trigger wheel has nubs at about a 2 degree interval, so it's just a matter of counting them and checking the CAS.

Mine was set around 20 degrees advanced, and I could increase it slightly with the adjusting screw to get it to run, but not at anywhere near a 76 Degree Trigger Angle! Not without that 72 Degree "move the trigger wheel trick" posted on the Cardomain site.

 

This kinda digressed from Badjuju's original question which was about running his setup. If he has an 81ZXT, then he has a decision to make. His post is a bit vague on calling things CAS and Dizzy, so I'm not sure what he currently has....

 

 

 

In his first scenario, with MS and MSD with an 82/83 Dizzy. I would say "No", you want the 79-81 Dizzy from a N/A vehicle. The 82/83 has some built-in advance that it gets tricky trying to get anywhere below 11 degrees initial timing a idle.

 

For the SECOND Scenario, suing MS-n-S, I would say "NO" you need an 83/83 CAS, which happens to be IN the distributor, but will NOT work as a distributor in earlier models. I don't knwo what the modify the CAS in his dizzy comment means---if he has an 81ZXT, then all he has to do is change the timing on the current CAS, and install the MS unit! if you plan on putting an 82/83 CAS unit into an earlier car, you need the drive spindle from the doneor also, as the drive spindle is different between the Turbo CAS unit, and all the other distributor/oil pump drive spindles.

 

He totally missed the option of skipping the distributor option altogether, installing a Plug in the Dizzy Drive hole, sticking in an LD28 Oil Pump stubdrive spindle, and using the MS-n-EDIS option after installing a 60-1 Trigger Wheel!

LOL

[Phyxius]

Exactly how did you set yours up? i ran my car to the "Full Advanced" position as limited by the bracket, and when checking the timing with a separate timing light, I would only get around 30-32 degrees total advance. The car would run fine under boost but off boost the thing was soggy (compared to now!)

 

I just hooked it up the same as the 82-83 dizzy and set the trigger angle... I don't think that I even had to advance it all the way. I had a lot of problems getting the car started when I first got the MS. It turned out that I had a burned circuit in my relay board. It's been a while since I did it, so I don't remember all the details.

 

How can I check how far it will actually advance?

[midnightzxt]

Hey tony, just so you know, I had the same problems you did with the 82 dizzy, but it was easy for me to fix. I haven't read all your problems you had posted, so i just want to know if you did this or not.

 

When my idle sucked and i couldn't get advance, all i did was pull the oil pump under the engine and turn the shaft a gear or two advanced. Reinstalled it and then tried again, after about 3 tries, I had the gear in the right spot for a good idle, and everything is fine and dandy. I'm not sure how the 81 dizzy is, but i know the shaft is the same principle. Had you done this?

[badjuju]

I had read (or thought i had, it was kinda late... lol) in a post by you that you had to screw with the bracket in order to advance, so that's what i meant by modify the cas.

 

So, if i just want to run MS, can i do so with my setup right now? everything is stock, except i'm running 311 cc injectors, and a 60mm tb. would my ecu operate right if i took the fuel portion of it's job away from it? exactly what do i need to modify in my car to just run MS, and use my stock ignition setup?

 

 

also, which parts do i need when i buy the ms setup?

[Phyxius]

i'm pretty sure...that like Tony said, it will RUN with the stock setup...but you may or may not be able to get a 'good' total advance out of it...

[Tony D]

i'm pretty sure...that like Tony said, it will RUN with the stock setup...but you may or may not be able to get a 'good' total advance out of it...

 

Total advance OFF BOOST.

 

To check your total advance, you have to look in your bins---and then do the condition to make them happen. What I did was set my advance light to 40 degrees (Mobys Initial Maps) and marked the trigger wheel. When you rev it, and snap the throttle closed, you WILL hit the high-MAP high-RPM bins that require 40+ degrees of total advance.

 

If your makr on the trigger wheel does NOT line up with the "Zero" mark (this is what turning the advance-style timing light does, negates your timing so you can read the timing as a "zero sum") then you know your trigger point is not correct. How MUCH incorrect is determined by what it says when you do the test. If your timing light is above the Zero mark, then you have to advance the trigger point further. In my case, the trigger point was under the waterpump someplace, and then triggering off the wrong paddle was another problem I had...but let's not get down there right now.

 

The car ran fine on boost. I would get my full 24 degrees. But terminally I would only get around 32 degrees. Typically, you need 35 degrees to run well under light throttle off-boost conditions (for best fuel economy)and decent throttle response. For fuel economy you need to add in that extra 7 degrees of vacuum advance that you would get at the same time---meaning 35+7=42 degrees total advance.

 

Without that full advance, throttle response is a bit off, sluggish if you will. And on-boost response (transition) will make it be a little sluggish as well.

 

The best I can describe it was it felt like my car when it had triple blowthrough carbs running far too rich. It felt like it was being "held back" somewhat. It actually, well, uh....FELT STOCK when it came to boost in first and second gears.

 

AFTER I did my modification...MAN! The way it pulled was incomparable to before. Throttle response was CRISP, and the car would bump off the rev limiter in first and second. It would rev that quick!

 

So check your timing with an adjustable light. Doing a quick 'snap test' will tell you where it's at!

 

JUST BE AWARE! The "TDC MARK" on an 81ZXT is NOT the paddle! It is a line on the timing disc bolted to the pulley! THERE ARE TWO DIFFERENT MARKS! One lines up on the CAS, the other lines up on the "Timing Scale" on the right side of the engine.

 

Stick a pencil in the #1 cylinder and when it's near TDC on the compression stroke take a look at the timing disc and clearly mark the "TDC" line on the disc. This will save confusion down the road (BELIEVE ME ON THIS ONE! LOL)

 

THAT is the line you need to watch to see where your timing is really at. If you use the paddle as the "trigger", you will be off by 20-24 degrees!

[Guest bastaad525]

This is very interesting.... so Phyxius might have gotten this working well w/o any modification of the CAS? Tony did you ever get those pics of the bracket?

[Phyxius]

Unfortunately, I don't have one of the total advance timing lights...I opted for the cheaper one...lol

 

And I'm pretty sure that I've been reading my timing by the correct mark

[Xander]

With the new ms&s-extra system you can trigger the unit at any angle upto 122 degrees.

 

This way you can probably trigger it with the stock setting.

[badjuju]

Agh, elaborate on that one... how does triggering it way past what it's supposed to be help us?

 

Tony, do you have any pics of what the hell you're talking about? i'm searching zcar and here trying to figure it out and find some pics, but i'm having trouble.

[Xander]

megasquirt needs to be trigger at least 5 degrees or soo before max advance . So you need to trigger about 50 degrees advance.

 

as I understand it the stock system Tony used can not be advanced more than about 40 degrees.

 

So you can never get full advance because you can't trigger the megasquirt early enough.

 

Now remember that your CAS triggers ones every 60 degrees. With the new ms&s-e you just tell the system to trigger it 50+60 degrees = a total of 110 degrees.

 

Normally megasquirt triggers like this.

 

trigger1-->spark1-->trigger2-->spark2-->trigger3-->spark3

 

on the ms&s-e you get somthing like this.

 

trigger1-->nospark-->trigger2-->spark1-->trigger3-->spark2-->trigger4-->spark3-->

 

You still get a spark after every trigger only the two corresponding trigger/spark are further apart thus giving you plenty of time to get full advance.

 

I hope this comes across, It's pretty difficult to explain in writing.

[Phyxius]

i think this is what they refer to as the 'next cylinder' setup...maybe i did this not knowing...lol

[badjuju]

Yeah i think i get it, that's a pretty good way of explaining it... does that mean it will have a problem starting up? or if not a problem persay, a lag?

 

if i were to go with ms&s-e, what all do i need to get in the package? maybe i'm just an idiot, but i find this all fairly confoosin.

[Phyxius]

it is definitely a lot to take in at once, but don't give up... Just keep reading about how the stuff works, and don't make it more complicated than it is.

[Tony D]

I would say if the setup like Xander is talking about, with "E" then hell yes you could get it to work!

 

The 81CAS triggers off the crank, and indeed, about 40 degrees total mechanical advance is about what I could achieve. If I could slot the bracket and get another 5 teeth advanced on the trigger wheel, I think it would work unaltered (unaltered referring to the trigger wheel mod, that is!)

 

I am busy as hell right now. I got to get over to ianz's garage to take some photos of the bracket and do some prototyping OFF THE CAR...

 

I thought I took photos, but I didn't. And now the underbely splash pan is in place...so screw removing all that and laying in the dirt ot take photos again!

 

I will get better shots in the nice sterile garage of ianz! LOL

[Phyxius]

tony, which version of megasquirt are you using?

[Guest bastaad525]

VERY interesting

[badjuju]

lol yeah... and which of the boxes do you have? i need to get this ordered in a hurry if i want time to play with it this summer before i ship out to college...

 

 

Relay board? stimulator?

 

I work 50 hours a week and have cheer practice for about 10. i work 40 miles north of where i live, and cheer 40 miles south of where i live. i don't have much time to do research except at night, and at this point i am so f'd up tired that i cna't think straight. exactly what hardware do i need to make an 81 efi system work with fuel and ignition management?