Starting Issues

I sort of spoke of this in another thread, but the original subject was different so I'm gonna branch of and put all the issues in here.

Basically I've got a new 5.0 roller motor I've put in the car with carb and mechanical fuel pump. I'm also running a full MSD electronic ignition system including 6AL box, Blaster 2 coil, and the correct distributor.

So right now the problem seems to be I'm not getting spark at the plugs. I checked for spark at the coil following MSD guidelines: Pulled the coil lead off the distributor, placed it 1/2" from ground, disconnected the magnetic pickup line, put the key to "on", shorted the magnetic pickup wires and got a spark off the coil lead. Good healthy spark.

But when I go to crank it I'm not seeing any spark at the plugs.

D.Hearne: You said the plugs had to be firmly grounded when checking for spark. I've always had success checking spark with the plug laying in the vicinity of a ground. Is there some other reason that wouldn't work in this case?

I went and investigated with a multimeter. I've got about 11.8 volts across the battery. The switched power 12V lead for the MSD is reading about 11.6 volts right before the MSD. Voltage drops dramatically to about 1-3 volts upon startup. I realize that it should drop because of all the juice going to the starter but is it that much? Could there be a problem here?

The battery is brand new and is an optima red top. The engine cranks fine, it doesn't sound like its struggling at all. However in the course of trying to start it, I turned it over alot, could this maybe be the reason why its reading lower? Or do those batteries need to be charged when you first get them?

woodsnake said:

A new 12V auto battery should have around 13.7V or so. If you drained it from trying to start while sitting, it may ned to be put on a charger for a while. The bigger queastion is why you don't have any spark at the plug.
If al those parts you listed are new, it seems likely that you just have a loose connection some where.
I just went thru this with a "new" Accel coil. It had been on the car about three days, and shat itself already. Swapped coil out, purred like a kitten. If you have voltage from the coil into the distributor, is there any chance you left the rotor out? I don't mean to sound insulting, but sometimes stuff happens....

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Hmm yea I think I'll slap it on the charger then and see if I can get better results. I'm also gonna try checking for spark again this time with a grounded plug to see if it makes a difference.

No worries on the rotor suggestions, I do have it in there but believe me sometimes I forget to the do the simplest things, haha.

Tim65GT said:

When you check the spark it is with the key in the "ON" position. The MSD Ignition Box requires the voltage in "ON" and "START". Temporarily disconnect the solenoid "S" terminal so it doesn't crank, and check for the ignition voltage at the MSD box to see what the level is when the key is in the "START" position. Did you replace the pink wire?

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Ok so you're saying to check the voltage on the switched power leading going to the MSD box when the key is in the start position and the engine is not turning over? This would eliminate the massive voltage drop because of the starter spinning. So it should read 12V?

I don't think I've replaced the pink wire, is that the one that has the big resistor on it? I've heard its a good idea but I've never done it. Could this be contributing to the problem?

Possibly, there should not be that massive of a drop. Especially if it is cranking normally as you say.

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Ok, I don't mean to be thickheaded but I just want to make sure this is clear. The fact that the voltage dropped on the switched power lead to the MSD to 1-3 volts when the motor is turning over is a problem?

Actually the wire IS the resistor. The MSD box only requires the voltage at this point as a "turn-on" signal and is not supposed to draw much current. Our Stangs are old and age tends to cause hgher resistance to the wiring, contacts, and connections. So, Yes.

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I was doing some reading up on the pink wire and I don't think its a problem. From what I understand it was used to limit the volts to 6 or 7 to keep from burning up the points ignition.

However, my setup is as follows:

I bought a painless wiring harness with 3 constant power leads and 4 switched power leads. Shown here:



These leads go to a terminal block next to the passengers seat shown here:



Now, the leads I have coming off the terminal block are

-Switched power for the 6AL
-Switched power for a cooling fan for the 6AL
-Switched power for Taurus fan controller
-Constant 12V for Taurus fan controller
-Constant 12V for electric choke

The fuse block requires a switched power connection and a lead that runs to the battery. The painless kit says to "piggy back" off the old fusebox for switched power. Now the pink wire/resistor connects to the old fusebox right? Well instead of piggy backing off the old fusebox or just connecting directly to the ignition switch, I ran the pink wire (thats the wire running off the painless fusebox) to an aftermarket 30 amp relay and a 10AWG wire running from the same side of the relay to the starter solenoid. On the other side of the relay I attached a wire running to the ignition switch and then one to ground. Hence when the ignition is 'on' the relay closes and I get my switched power directly off solenoid.

So after that lengthy response I can't see how the pink resistor wire would influence my new circuit. Am I correct or am I a complete dolt?

Thanks guys, and any feeback on my circuit setup is welcome.

Also here is a picture of sort of the whole passenger floorboard:

I was talking to a friend today and he said that there are some posts on the ignition switch that will have power in the 'on' position, but not the 'start' position. Can anyone confirm this? If that is true, it might be the problem because I sort of arbitrarily hooked up my switched power lead to the only post I could see.

I believe what I posted above is indeed the problem. After doing a little research it appears it is best to hook the switched power lead of the MSD off of the red/green coil wire by the ignition switch.

Curiousity got the best of me so I hooked the switched power lead to a constant 12V terminal to see if it would start...and it did! It roared for about 5 seconds if that and died. Upon subsequent attempts I could only get it to start for that amount of time. Any thoughts on that? Timing?

Also I noticed on the last try to get it start some smoke from the starter side of the starter solenoid. Could that just be because of so many start attempts? Should I just let it cool and not worry?

Also, putting my MSD on constant 12V shouldn't do it any harm right?

Has anyone ever had a really difficult time trying to rotate a distributor after installing it even after removing the hold down clamp? I'm having that issue now. I can't get it to budge.

Well ignore that last thing I said, i got the distributor loose and advanced the timing a tad and this is the result:

http://www.youtube.com/watch?v=F2VDLvLXrR8

It started fine and I was really excited about it but I'm not convinced its timed right yet. For 289/302s engines generally where is the number 1 spark plug located on the distributor at TDC and 10* BTDC? Mine was at about 1 oclock at TDC and around 2 oclock once I advanced it. Those positions should always be the same regardless of distributor install correct?