Need Advice on Ignition system(coil, EI, plug gaps, etc)

[Drake240Z]

Hey Guys,

 

I'm a relatively new Z owner.. I bought a 1971 240Z at the end of summer, and I've been trying to get it into top running form. One of the previous owners put alot of work into it, but one thing that has been giving me a headache is trying to figure out what to do with the ignition system.. I've done alot of searches, and research, but the more I learn the more I don't know what to do.

 

Basically I would like to upgrade from the old points system to electronic ignition, and just get the best possible setup. From what I've read It seems everyone has a different opinion on which way to go..

 

It currently has an Accel super coil, but after reading the specs online I'm a bit worried about the part where it says "Effective up to 6500rpm". My 240 has a .280 cam and has been balanced to handle high Rpms, and although I don't like to do it, it will go past 7500rpm.. But now that I'm thinking about it I'm not sure its really pulling as hard as it should past 6500. Maybe I'm just imagining that though. (I would go test it right now, but since I can't get it through emissions testing I can't put regular insurance on it, which means expensive permits.. That and I avoid the wet weather like the plague.) I would like the ignition to handle up to 8000rpm to take advantage of the cam, not that I plan on taking it that high very often..

 

Then theres theres upgrading to electronic ignition.. I'd like something easy to upgrade where I won't have to replace the Tach.. Pertronix sells a kit which sounds like an easy upgrade, but I'm not sure if it will work with my coil, which I don't know if I should keep... And it all needs to look original, or be from the 70's-80's period for my car to qualify for a local Vintage car race I'd like to take part in.. ahhh, that headache is coming on again

 

Part of this upgrade is to try and get the car running as efficiently as possible to help with the emissions testing.. If I can squeze it through without having to get it specially tuned, and retuned, while spending the money on what I should be upgrading anyways I'll be very happy.

 

I'm really at a loss to which way I should go here..

 

Any advice that you guys could give would really help.

 

[NewZed]

Wow, those Accel coils seem to be mysterious and magical.  They don't list any specs. for the coils, they're all "Super" and they have instructions like this - "New resistors will smoke initially in operation and get extremely hot.  This is normal".

 

http://accel-ignition.com/original-super-coil-points.html

 

http://accel-ignition.com/media/instructions/accel/ACCEL_Instructions_universal_super_coil_140001.pdf

 

 

You've got a bunch of options.  How much do you want to spend and how simple does it need to be?  You can probably get a good conversation going on whether or not any distributor-initiated ignition system will handle 8,000 RPM.  Let alone a stock (except for balancing, whatever that means) L24 engine with just a different cam.  Don't forget to consider tachometer accuracy also, the needle may not be showing true RPM.

 

Revving around at 8,000 RPM does sound like fun though.

[Drake240Z]

Wow, those Accel coils seem to be mysterious and magical.  They don't list any specs. for the coils, they're all "Super" and they have instructions like this - "New resistors will smoke initially in operation and get extremely hot.  This is normal".

 

http://accel-ignition.com/original-super-coil-points.html

 

http://accel-ignition.com/media/instructions/accel/ACCEL_Instructions_universal_super_coil_140001.pdf

 

 

You've got a bunch of options.  How much do you want to spend and how simple does it need to be?  You can probably get a good conversation going on whether or not any distributor-initiated ignition system will handle 8,000 RPM.  Let alone a stock (except for balancing, whatever that means) L24 engine with just a different cam.  Don't forget to consider tachometer accuracy also, the needle may not be showing true RPM.

 

Revving around at 8,000 RPM does sound like fun though.

 

Thanks for the reply. in terms of price I'm willing to spend a fair bit if the benefit is worth the cost.. The main thing is that in order to qualify for the vintage car race my 240 can only have period modifications. The class I would be entering it as would be 1970-1980, so upgrading to a modern aftermarket system wouldn't be allowed.

 

Its kinda odd that they don't list much in terms of specs for the coil, but I did find them on another site: http://www.autoanything.com/ignition-systems/74A6547A0A0.aspx

 

From what I know the engine was balanced and blueprinted. It has a E31 head, 280duration cam with .506 gross lift, stronger valve springs, and triple weber carbs... So not exactly stock.

 

From the research I've done with that cam the max power should be around 7600rpm..The tach may not be 100% accurate, but it doesn't jump around at all so I'm sure its fairly accurate, and I really don't want to go aftermarket. I like the original look, and thats one thing I don't want to sacrifice.

 

The highest I've ever reved it to was around 7800rpm, but only because some douchbag didn't feel like letting me merge, so I had to put the hammer down.

 

The Pertronix kit I mentioned converts the stock distributor to electronic ignition, so it wouldn't be obvious to the scrutineers, but I'm not sure how good it is, or if it would work well with my coil. The other option is going for the ZX electronic ignition, but that requires a bit of extra work to get the tach to work.. I don't mind doing the extra work, but only if it will give me better performance.. Somehow I doubt 30 year old technology will be any better, but some people swear by them.

 

Heres the Pertronix kit I mentioned. I've seen it on several online Z shops, so it seems to be a pretty common mod: http://www.thezstore.com/page/TZS/PROD/12-4020

 

I did come across this: http://www.classiczcars.com/photopost/member-galleries/p7065-ultimate-ignition-setup-3f.html

 

It wouldn't qualify for the race, but maybe if I came up with an easy way to intall and uninstall I could use that with my existing setup and just remove it for the one time a year I'll actually race it.

 

I dunno, maybe I'm just over complicating things, But I really don't know much about ignition systems and I don't want to start throwing stuff together with no idea whether it will actually work properly

[Six_Shooter]

It would be very easy to make the MSD a plug in system, but I'll leave that alone for now.

 

What I would do in your position is get a later dizzy, from a 260Z or 280Z, even a non turbo 280ZX dizzy can work. These are not points triggered systems, but use actual ignition modules to charge the coil. They offer higher charging current, for hotter spark, and more accurate timig since there are no moving parts that trigger the coil that can bounce or have issues at high RPM like points systems often experience. This swap could be done to be nearly invisible, or invisible, depending on how far you go with hiding the small change in wiring.

 

These links may help:

http://www.zhome.com/ZCMnL/tech/ZXPertronix.htm

 

http://www.zhome.com/ZCMnL/tech/ThomasMSD.htm

 

Here are a few dizzies I have: 

Far left is a 280Z dizzy, 1977 IIRC.

Next to it is another 280Z or ZX dizzy.

The one with the brown cap is a 260Z dizzy that uses an interior (remote) mounted ignition module

The far right I believe is a 280ZX dizzy (non turbo) that has the ignition module mounted right on the dizzy itself.

 

 

Look at the FSMs for the 260Z and 280Z will show they are connected, along with the above links.

 

Back to the MSD ignition, since you can use the "points" trigger to trigger the MSD box, this can be attached to a simple plug, that when you want to remove the MSD ignition you connect a "shorting" or "bypass" connector in place of it.

 

The other part of that is that the MSD 6, quite possibly the 6AL ignition were available in the '70s and should be considered a "period correct modification".

 

As long as the MSD ignition is considered a period correct modification, you can use the later dizzies that use the remote mounted ignition modules to trigger the MSD ignition through the magnetic trigger connection and simplify installation, without the need for the bypass plug.

Edited February 22, 2013 by Six_Shooter

[Drake240Z]

Your post was very helpful, Thanks

 

I didn't know the MSD 6a was made back then, so thats great news. I'm thinking the 280zx dizzy with the 6a and my current coil would be a good system and still all period correct..

 

I'm still wondering about the "effective to 6500rpm" in the coils specs though.. Is there another coil that you would reccomend that is still period correct?, or should I just stick with the one I have? I'm also unsure if I'll need the ballast resistor with that coil.. I'm guessing not, but again i'm a total newb when it comes to ignition systems.

 

I'll have to figure out how to wire everything up together properly, but those diagrams you sent me along with whats in the various shop manuals I have laying around should help. Of course the instuctions for the units themselves will help, but I'll probably post a diagram of my own to be sure though once I've got that figured out.

 

Once I have this system setup, what kind of Sparkplug gaps could I run? From what I've read alot of people run .045 or .050, but I've heard of even wider.. My carbs are running  a bit on the rich side, so wider may be better for me, but I don't want to go too wide... I may have to play around a bit, but any suggestions or experiences would be appreciated.

[JCan]

Drake.

 

We purchased a 280zx distributor and had it rebuilt by Advanced Distributors (http://advanceddistributors.com/).  They modified the centrifugal advance and the vacuum advance (we use manifold vacuum).  The nice thing about this distributor is that is is period correct and the electronics are designed for high RPMs.  The down side, is that you may have to replace your tachometer electronics with modern internals ($157 at redline gauge works).

 

Regarding whether your coil works at high RPMs:  All a coil is is one long wire with a tap wrapped around an iron core.  Your ignitions ability to supply spark at 8k rpms is related to the ignigiton module, wires, capacitor and spark plug gap (if you have a high spark, should be gaped somewhere between .040 and 0.050" mine is at 0.045").  Notice I mentioned capacitor.  Do you have one connected?  If you don't, it is very important you connect one up.  The capacitor acts like a small local battery to supply energy to the coil and becomes more important as RPMs increase.  IF you dont have one, get one!  It goes on the ignition switch side of the coil to ground.

 

So how do you determine if your setup works.  I suggest you use the coil and electronic ignition you already have, and for ~$150.00 take your car to a dynomometer and have the attendant monitor your ignition timing, spark advance and exhaust air/fuel mixture.  Run the car to 7500 rpms and take a look at the results.  It will be apparent that your ignition degrades at high RPMs by looking at the air fuel ratio (too much fuel) (or the tach on the dyno will start to bounce when your ignigion degrades significantly).

 

The great thing about this?  You can have your webbers air fuel mixture adjusted at the same time!

 

When you are done, your car will run great and you will be sure your spark is hot, timing is correct, and air fuel mixture is also correct.

 

my two cents!

 

Good luck!

 

Jim