bypassing ballast with stock ignition module

-
Muscley MOPAR

Muscley MOPAR

Well-Known Member
Joined
Oct 29, 2011
Messages
163
Reaction score
1
Location
hull iowa
ive got a 360 on a starting stand and about a year ago the msd 6al box quit working. so i sent it in they "fixed it" and i got it started again. now im getting it ready to be put in the car but at mid to high rpm its misses and cuts out. what im trying to do is put in a stock 5 prong ignition box in to see if my issues is my "fixed msd box" its a magnetic pickup dist and a msd Ecoil and i bypassed the ballast went right from ignition to + coil to top prong on box and i get no spark. but i do get spark when i flip the switch off on the ignition switch...and i have 12 volts on + coil side and a low voltage leaking through on the - side any thoughts
 
An OE 5 pin ECU has a functioning 5th pin (where the red/green wire is). ohm it to the case & if it has resistance then it is one of them (aftermarket 5 pinners have a dummy 5th pin which will show infinity/its just for appearances!) cuz people were complaining that it ain't right cuz it is missing a pin! so they added a dummy pin so if yours is an OE type then the blue/yellow and the red/green ECU pentastar terminals need fire in ign2 "crank". Also on the miss check plugs/plug wires (as you know) and rotor phasing and excessive timing expecially vac adv (if used). the start circuit thru the other half of the 4 terminal (dual) ballast has a nominal 5 ohms spec but might be ~6 ohms & that is the circuit that needs to go to the red/green wire at the ECU. EDIT if you dont have the 4 terminal (dual) ballast handy to go along with the OE ECU you might be able to jump to the red/green for a second while cranking just to get it started. wouldn't be good for it but it is an expendable piece. Do ya feel lucky? well do ya
 
Muscley MOPAR said:
ive got a 360 on a starting stand and about a year ago the msd 6al box quit working. so i sent it in they "fixed it" and i got it started again. now im getting it ready to be put in the car but at mid to high rpm its misses and cuts out. what im trying to do is put in a stock 5 prong ignition box in to see if my issues is my "fixed msd box" its a magnetic pickup dist and a msd Ecoil and i bypassed the ballast went right from ignition to + coil to top prong on box and i get no spark. but i do get spark when i flip the switch off on the ignition switch...and i have 12 volts on + coil side and a low voltage leaking through on the - side any thoughts
Click to expand...


I would not bypass a ballast in a stock box. You may or may not HAVE a 5 pin box. Only way to tell is to use a multimeter on the "5th pin" and see if it's connected. Don't forget that Mopar gets the ground through the box. IT MUST be grounded.

The difference between 5 and 4 pin boxes is the dual / single ballast. A 5 pin box MUST have a dual ballast, and a 4 pin box does not matter because that pin is not used

5 pin

Ignition_System_5pin.jpg


4pin

Ignition_System_4pin.jpg


I went a different route. I use GM 4 pin HEI on mine, and one day I needed to fire up a junk engine. I occurred I could 'have' a complete emergency ignition "in a box." Here's what I did:

zu5qn8.jpg


Plug in distributor and coil wire, hook green to ground and yellow to battery, and we have ignition!!! On a side note I see I didn't "follow my own advice." Pickup leads, really, should be twisted

hwlcfa.jpg


Fired this mess up, didn't even put manifolds on it!!

34nf6l0.jpg
 
Rusty I had no idea you could do that, it did not shake itself off of there! yes the HEI is a nice setup & with an E coil you can run full voltage to it & the HEi and you can also mount the HEI under the dist & someone even makes a plate for that but it is pricey & it's super easy to fab yourself, just use radio shack heat sink paste between module/plate
 
thanks guys! wires and plugs are good distributor was on my check if its good list but i wanted to start with the msd box since the "fixed it".so ill check what my 5th pin has, it came off my 79 ramcharger that was good when i swapped to a FI magnum. so if the 5th pin is used i would have to go from positive coil to that pin instead of the top pin right? or i could just do what 67dart273 did and use the gm ign. your dark blue is basically just a hot ignition lead correct? i just need it to see if my msd box is really the issue thanks again
 
If the 5th pin is live you MUST use the dual ballast Look at the top diagram (5 pin) I posted. Look at the far left wire labeled "new wire" It is labeled that way because "they" were wiring this up from scratch I guess. A harness would already have that. In the diagram it goes to the left side of the ballast. Notice the "U" in the ceramic block on one end. This is so you can tell the two apart, the section on the right side on that page IS BASICALLY THE SAME as the old points ballast and wiring "does not change" for that section.

IN FACT let's say you have a working 5 or 4 pin Mopar ECU setup, and it quits. "You" just happen to have a points distributor in the trunk. You can grab it, unplug the box and the electronic distributor, slam the points dist. in there and hook the wire back up to coil NEG and it will run fine, and be wired right for ballast and the bypass circuit.
 
i guess what im trying to do is wire up the old ecu without the ballast because im running a 12 volt coil and if im not mistaken the ballast cuts down the voltage to 6 volts because the stock coil is a 6 volt coil. i thought ive heard of people taking their ballast out and just putting in a lead between in its place. im just trying to figure out how id need to hard wire it so it would run and i could see if my msd box was bad. unless what your saying is that the 5 wire ecu needs the dual ballast to run i somewhat get the dual ballast diagrahm but not sure where the "u" wire goes
 
Just look at the 5 pin (top) diagram. The "U" is at the bottom of the resistor. The top two pins of the resistor are hooked together and go off to switched 12V "run."

The bottom left terminal is coming off the section for the 5 pin ECU. THAT WIRE (far left) goes down to feed the corresponding pin of the ECU

So far as I know IF you have a 5 pin ECU, that cannot be eliminated. The box is designed to run off that power

The 4 pin boxes are powered internally by a direct 12V feed same as the second 12V wire in the 5 pin, IE the wire coming off of far top right, going straight down the page to the box.
 
well i grabbed a gm hei and im goona wire that up and see what happens...plus like ya said "emergency ignition" the skinny terminal goes to the male distributor connector in your diagram correct
 
Muscley MOPAR said:
because im running a 12 volt coil and if im not mistaken the ballast cuts down the voltage to 6 volts because the stock coil is a 6 volt coil.
Click to expand...
Not really, it is a coiled design to work from 12 WITH the proper value of ballast. The actual coil voltage will depend on the ballast value (which changes with load) and the RPM some a lesser degree, and can be a lot higher than 6 volts.

One thing not yest discussed is if you have the right ballast IF you have a 4 pin ECU. There are a lot of different ballast resistors out there and only 1-2 are right for the Mopar system. The wrong one can kill spark energy and cause your symptoms.
 
i did get it goin with that gm hei module but the miss was still there i tried doin the timing by ear rather than with the gun and it got a lot better but it was still there. but i ran it for a bit and i heard a slight tick under the valve cover so impretty sure i had a adjuster come loose and my valves is staying partially closed ill have to rip the cover off and check saturday thanks for the help guys
 
This heat sink is available from Grainer for not much. Some say it is overkill but better too much than not enough....

vbpgimage.php

vbpgimage.php
 
Motor is running way better now. Ive found that the methods of setting valves the stock way with it on top dead 1 then top dead 6 or the turning the motor every 90 degrees then adjusting is not a very accurate way of setting valve specially on a motor with long cam lobe duraton nd big lift, doing them one rocker at a time right in the middle heel if the lobe is the best way to do it may take a Lil longer but much more accurate. It has a hard time starting with the dist in the postion where it runs best but it is a E-85 motor nd that's a Lil harder to get started with higher compression, it will start much quicker squirting regular gas down the carb, may have to do some fine tuning in the carb nd timing possible dyno tune we'll see
 
You must log in or register to reply here.
-

Back
Top