Hey im building a sbc in my 87 trans am and we are not using the computer. I heard that you need something to run the ignition since there is no computer to run it. What is it that i will need?

 

all you need is an HEI dist. and a ing. hot wire, and 12volt source, or you could go to the high end and go MSD

 

Ok thanks. But what do you mean by "an ignition hot wire." I have the 12v battery and the distributor.

 

Switched ignition source. When you turn the key you need power to go to the ignition system. You don't want your ignition to be hot all the time, only when the key is on.

 

ok so what all do i need to do? Are you saying that i need a switch to turn off the ignition after i turn over the car? Also i heard you can get some sort of "box" to run the ignition. What would that be?

 

If you want a Box you need a complete MSD setup with a 6al box, MSD disty and coil. If you dont want to spend $500 on your ignition then all you need is a HEI disty that you run a power sorce to from any wire that is hot during crank and run.

 

Just get a MSD Pro-Billet HEI Distributor, you do not need any other parts, it comes with instructions that tells you how to wire it up and it is very simple. Make sure to set your motor to TDC#1 before you pull it out then you put the other one in, wire it up and fire it up then check the timing and set it and you're done.

It's about $360.00, they also make less expensive ones.

 

What kind of distributor do you have? Depending on what kind of dist. you have there are several options.

 

do a google image search on ignition wiring.
i think i have a basic diagram at home i can post if google doesn't show you the basics.

all you need electrically/electronically to run the engine is
- 12v battery
- ignition key switch (off/run/start)
- the starter {and solenoids for type & model of starter}
- distributor {with points or electronic module}
- ignition coil

+12 wire from battery to battery side of ignition key switch, when key is in run position that run terminal of switch has wire from it to + side of ignition coil. This is what makes the engine run {electrically}. When you turn the key to off, no more power to coil which kills ignition and shuts engine off {gas engines turn off by killing the ignition which is electrical as opposed to shutting off the fuel}.

the start side of the key switch wires to the starter solenoid,

the - side of ignition coil is run to breaker points if it's old school setup, or to electronic ignition module. The electric circuit between ignition coil - side and ground is opened and closed by either the points or electronic ignition module which causes the coil to fire and send spark to the plugs. This is all there is to it with the exception of relays here and there to switch high current, usually the ignition key ignition wire will go to a relay instead of directly to the ignition coil + post, that way high current isn't going through the ignition switch whenever the engine is running which will shorten the life of the switch. same thing for the starter wiring. and for the alternator that is basically just a parallel connection anywhere on the + side of the electrical system (i.e. alternator output wire to battery + post).
Even as you get into the fancier ignition systems, it's still the same basic wiring setup in terms of power supplied and grounding. all that's really added is an ignition box (microprocessor) to control timing which is triggered off the distributor.

the hard part is deciding how much $$ you want to sink into an ignition system. From the sound of it, you want a simple electronic ignition controlled by the distributor (as opposed to distributorless using crank position sensor/computer like LS1). Pertronix is decent, and mallory and msd and accell too i think all have billet distributors that have vacuum advance and the electronic module under the cap to control ignition timing.
usually for little $$ more you can upgrade to an "ignition box" setup that will allow give you more timing adjustability, or allow you to make your own timing vs rpm curve instead of being stuck with a fixed timing curve when it's a distributor with mechanical timing advance, which is probably what you'll want.
also check out ignition system at howstuffworks.com, and just browse jegs or summitt to see what's available for distributors and ignition systems to get an idea.

 

I have an MSD Crank Trigger with an MSD Pro-Billet Front Drive distributor on my new motor. I will be running it all with an MSD 7AL-3 ignition box.

To control a computerless car you will need an ignition box like a 7AL-3 (not that exotic for a lower powered street/strip car).

 

I have an HEI dist and a coil. I called MSD and they told me i need an ignition control module, dist, and coil. So, if i have an HEI dist i dont need the ignition box(control module)? But if i want i could upgrade to the box setup? Or do i need the box no matter what?

1 FMF, cant i just use the ignition switch that came with the car?

 

the GM hei distributor & coil setup was designed so that is all that's needed to run the ignition. You only need to give it 12v power and it works and the engine runs. You don't need an ignition control module, it sounds like msd is selling you add-ons which will make the gm hei better but you do not **need** it to make the engine run. Be careful when asking about stuff like this because if you don't know people will sell you on a bunch of stuff that you don't necessarily need and may not want.
http://www.customclassictrucks.com/h...ade/index.html
http://www.chevyhiperformance.com/te...les/index.html


if you're referring to using the ignition switch to feed the hei distributor directly, that is not a good idea. It will work, but the coil will draw around 6-10 amps of current which the ignition switch probably isn't rated for and if it doesn't fail outright it'll end up as as resistance in the circuit preventing full power from reaching the coil and causing you mysterious problems when running that you'll diagnose as something else and go nuts on. And if you were to use the ignition switch to feed the coil, that is a long run of thin gauge wire so you'll will probably have a voltage drop across it and not see a full 14v at the coil when the engine is running. And that circuit is fused with power coming to the ignition switch probably from the interior fuse panel under the dash / steering wheel, probably a 10A fuse, and most likely feeding other accessories inside the dash. If you run that circuit to the ignition you'll be overloading it and most likely blow the fuse, or burn contacts and melt wires if the fuse doesn't blow or you throw a 20A or 30A fuse in there.
What you want to do is run the ignition wire from the ignition switch to a relay near the coil or at least in the engine compartment. This ignition wire from the ignition switch will be 14-18 gauge (thin) because the low current side of the only needs... low current. And it has to be thin to fit in the steering column and snake through the firewall. You feed the high current side of the relay with heavier gauge (10-12) wire- wired properly the high current side will also be fused (15A) getting power from the fuse box under the hood somewhere and having the heavier 10ga or 12ga wire that is now a nice short run going to the coil, that way the coil gets full 14+ volts with engine running with little voltage drop.
You probably already have a relay in the fuse box under the hood, it'll be labelled... ignition but if you're rewiring everything and junking fuse boxes that are old and crappy, relays are universal and cheap. I know radio shack sells a 20A automotive relay for $5.99 that you can manually wire in real easy for just ignition. And i'm sure jegs and summitt have many to choose from too .

 

hey man thanks alot. I was confused at first i thought you meant that i needed to run another ignition switch in addition to the standard one. So what is that conrtol module box used for then if you dont actually need it?
Also do you have a wiring diagram i could see that shows the correct setup?

 

The box will allow you to run more than the 24* of mechanical advance the disty alone will allow, plus it has some features like a rev-limiter and other ****, just look around on Jegs web page to read about what all they allow you to do.

 

ok so can someone please clear this up for me...
I run wire from the ignition switch to a relay and then to the coil. What else do i need to wire? In the haynes manual it has a bunch of wires going from the ignition control module(which is right under the distributor cap) to the PCM. What do i do about these wires? Do i need them? If anyone knows where to find a wiring diagram that shows how to wire up an ignition for a non computer controlled car and without a MSD ignition box please share!
Thanks
EDIT: I heard that you cant use a computer controlled HEI dist like mine in a non computer controlled application. Is this true?

 

Anyone?

 

the following pic is a basic diagram. sorry for the wait, been busy.
there's many ways to make an ignition work but without knowing exactly what you got I can't really tell you how it should be wired. and i know nothing about how an 87 transam was setup, but if you can post a pic of your distributor or email me what the haynes manual has I can probably help.

 

yeah i can get you some pics/info tomorrow(the haynes manual/distributor are at my uncle's house). But i do know that the dist. was in a computer controlled TA, and we werent sure is you could use a comp controlled dist. in a non comp controlled car without buying some sort of ignition box to control it. I was hoping not as those boxes are pricey and im running out of money.