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  #16 (permalink)  
Old 05-20-2010, 12:50 PM
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This has only been happening since i just installed my new motor over the winter. I was able to break in the motor and drive it about 50 miles before i began having issues.

I've gone through 3 of these ignition boxes, the first one ended up having a bad diode after being used for 5 years, the 2nd one i got back from having the first repaired/replaced and it ended up being even worse - i couldnt start the car without the ignition box acting up flickering and bogging the vehicle down. Now i have a tell tale sign before ill start having problems, the stereo will begin cutting out and gets worse before the box begins to act up...meaning the box isnt receiving 10v or more.

I will try and move the 12v main wire to the battery. Mallory is who the CD box is through. Prestolite is who makes it. I was also thinking of pulling a remote wire from the battery and wiring it to a switch.

The box is connected directly into the coil. Its a brand new coil. I do have another coil that should be good that i can 'try' and see if that works.

My tach is also jumping around, it wont read a correct RPM to save its life. Some times it will but 89% of the time it is off by hundreds/thousands of RPM. Checked the ground, power, ignition wires for the tach and they're all fine.

Maybe i should buy some cheap'o dizzy off summit and ditch this CD ignition BS im having so many problems with...

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  #17 (permalink)  
Old 05-20-2010, 02:03 PM
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Personally I have never had good luck with Mallory ignition parts. I have and always will use MSD since the last Mallory box left me out of a race.
Sounds like to me if all was working fine until you installed your new motor then I would be looking at whatever changes you made to the wiring when you made your motor swap. I everything is the same, then I would be inclined to think you have a bad ground in your ignition system. If you are using a Mallory distributor also, it will have to be grounded to the block with it's supplied ground wire, nit into the cars ground wire system. Feedback from this is crazy.

MSD, MSD, MSD and tap your heals three times.
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  #18 (permalink)  
Old 05-20-2010, 02:19 PM
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Quote:
Originally Posted by Ignitrous
I have my battery in the hatch area of my 73 nova. The batterys ground is about 12" long and bolted to the body.
While this may be sufficient for most vehicles, there are cases where there's too much resistance using the body/chassis for the ground path.

In any event, the positive cable needs to be large- as in 1-0 gage- not some wimpy 4 gage.

If I were going to add anything, it would be a dedicated 1-0 gage ground wire from the battery all the way up to the alternator bracket, then another strap from the bracket to the chassis. Leave the strap from the engine to the chassis that you already have. Add another ground strap from the engine to the body, like at the firewall.

Quote:
When i was changing out my Alt i turned the electric cut off switch to "OFF" while i was disconnecting the Alt I some how was able to arc a huge spark off the alternator, i could probably repeat this but i obviously didnt want to so I became very cautious/careful.
This could have been the switch not actually being off. If so- AND you grounded the BATT lug on the back of the alternator w/a wrench when trying to remove the wire, etc.- that will get you a hell of a spark. You didn't say what you were doing when the spark occurred, so I'm guessing.

Quote:
With my battery basically 'disconnected' how could i get a spark like that at the alternator?!?!
You can't- that's the point. Either the switch is defective, miswired or mislabeled.

Mallory- they have been known to have their 'issues'. I would at least try using a plain vanilla HEI, w/o any boxes, amplifiers, etc. to see if the problem will resolve itself.

I don't remember you saying how the alternator is getting current- from the starter, or directly from the battery, then from the alt. to the starter.

I still think you need a remote Ford-type relay/solenoid.
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Old 05-20-2010, 04:30 PM
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Quote:
While this may be sufficient for most vehicles, there are cases where there's too much resistance using the body/chassis for the ground path. In any event, the positive cable needs to be large- as in 1-0 gage- not some wimpy 4 gage. If I were going to add anything, it would be a dedicated 1-0 gage ground wire from the battery all the way up to the alternator bracket, then another strap from the bracket to the chassis. Leave the strap from the engine to the chassis that you already have. Add another ground strap from the engine to the body, like at the firewall.
I have 1-0 gauge power wire running from battery to fuse box then to the disconnect then up to the starter. The starter then has a wire that runs up to the common point on the firewall (horn relay that has a stud where 4 or 5 12v sources connect, one of them being the CD ignition box) and a separate wire also comes off that common point and is one of the 2 wires on the plastic connector on the alternator. There is 2 wires on the stud on the alternator, 1 that goes back to the battery fuse box to charge the battery, its like 4-6 gauge. Then other 1 runs to my electronic temperature control box for my electric fan.

Are any of these redundant? It has the original 2 wire connection in the top of the alternator. So a total of 4 wires are connected to the alternator. Im not sure if the way its connected is exactly the same as it previously was before the new engine went in.



Quote:
This could have been the switch not actually being off. If so- AND you grounded the BATT lug on the back of the alternator w/a wrench when trying to remove the wire, etc.- that will get you a hell of a spark. You didn't say what you were doing when the spark occurred, so I'm guessing.


The charge wire is connected to the shut off switch on the same terminal as the 1-0 gauge wire.


Heres a picture of my current set up.
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  #20 (permalink)  
Old 05-21-2010, 08:30 PM
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The one thing I am sure of is that your kill switch should be straight from battery and then to any supply. This will prevent any feedback that can occur in the current configuration of going through the fuseblock then kill switch. You still have power feeding circuits that are not shut off by the kill switch.
What is the fuse box feeding before the kill switch since you have an OE box in the configuration also? If it is just a main line fuse then it is ok as it is, but if it feeds anything you should reroute to switch first.
My thoughts are that you may be having a feedback problem. It's kinda hard to trouble shoot without knowing what changes you made during engine swap.

Last edited by a70dart; 05-22-2010 at 06:25 AM.
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  #21 (permalink)  
Old 05-21-2010, 10:11 PM
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Ok ill move that wire easy enough. I went and bought a multimeter tonight so ill be messing around with that tomorrow.
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  #22 (permalink)  
Old 05-26-2010, 04:56 PM
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Radio problem may not be with the ground

To see if it's the ground causing the radio problems, just clip a wire from the ground stud on the back of the radio directly to the ground terminal of the battery. That should "fix" the radio problem.

But as I read the description of the radio problem, it sounds more like an electronics problem within the radio itself, like a cold solder joint or a component overheating on its way to eventually failing completely.

With a trunk-mounted battery, I measure the length, consult the current capacity charts and choose the next larger size (since current-carrying capacity diminishes with heat and age) and run marine-grade cable with + going to the starter and the ground going to the block near the starter. From the starter and the engine ground, I run #8 cable to the alternator + lug and to a bolt on the back of the alternator. Those last two wires don't need to carry the current that the wires to the starter do. A separate #8 wire runs from the starter to a maxi-fuse mounted inside the car (heat reduces the current rating of a fuse) and then to the main fuse panel.

For any car made prior to 1950, corrosion and paint combined with steel body panels make for a poor ground, so I always use a dedicated ground system just like you would on a fiberglass car. More trouble initially, but I hate having electrical problems on the road when I'm trying to enjoy my car.

Why upgrade the battery and charging cables? For an OEM, pennies per car make a big difference for a million cars; for one car it's not a huge additional expense and is, I feel, worth the investment. BTW, welding cable is not an acceptable substitute for marine- or premium-automotive grade cable.
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Old 05-26-2010, 06:11 PM
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I think Cobalt and Hduff have you pointed in the right direction.

Battery ground attached to body in rear and then chassis-to-engine in front is a bad idea, especially with a unibody car like your Nova that has a seperate front subframe mounted to the body with rubber bushings. I went through a similar problem with my '72 Nova w/ trunk battery, ended up running a ground wire from the battery all the way to the bellhousing bolt closest to the starter and that fixed the problem. I used 0 ga welding cable so I would never have a worry about it again, for both positive and negative from the battery, no such thing as too big with these wires.

Your wiring schematic looks fine except for the battery ground to sheetmetal in the rear.

Hduff, care to say why you think welding cable is no good? I've used it for more than 15 years on my Nova without a problem.
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  #24 (permalink)  
Old 05-26-2010, 06:33 PM
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The welding cable I've seen is made up of smaller individual wires than similar gauge automotive cable. That's great for flexibility (which you want in welding cable) but vibration in a car over time causes strands to fracture, reducing the current-carrying capability of the cable. Plus the covering is rated more for durability and abrasion rather that heat.

It's more of a right-tool-for-the-job preference for me since it's not like welding cable will cause your car to explode (and I have also hammered a nail with a wrench before).
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