Still cannot start the car

[nealf]

If anyone was following, I have swapped my bogus roto faze distributor with a stock unit for my '70 2800cs. Now, I am thinking the bogus coil that is in there may be preventing me from getting the car running.

Does anyone know the stock coil for my car? Are they the same as a 3.0? Is it supposed to have a ballast resistor (external) like my car presently has? Thanks again

nf
'70 2800CS
'73 2002

 

[Malc]

You can use any coil from any car to get it running, make sure you wire up the low tension feed and earth the right way round +15 post is positive on a Bosch coil.

You don't have to have the ballast resistor for short term tests, but they do help to increase coil life.

So yes the one from a 3.0 will/should work

Your points and condenser ok?

It does work as I once go an MGB running with a coil from a VW beetle....
Keep on running.... left it in there :roll:

I think coil types are dependent on number of cylinders rather than make of car

Oh dear.... rambling again
Malc

 

[Philip Slate]

A coil is just a transformer that converts low voltage, 12 VDC, to high voltage, 15K-40K VDC, to allow a spark to jump across the electrodes of the spark plugs. This action is initiated by the opening and closing of the points. The ballast resistor lowers the voltage going across the points which is supposed to prolong their life and is not necessary if your just doing a test and the car will run fine without it although the points might burn out faster. A way to test to see if the plugs are sparking is: with the distributor cap off, turn the engine so the points can be opened and closed when you rotate the rotor back and forth. Take the hot lead from the coil that would plug into the distributor and place it about the width of a spark plug electrode gap (35-ish mm, 1/16 inch, whatever) from a chassis or engine metal part (basically any part going to ground - earth for Malc). Turn on the ignition making sure to not rotate the engine and then manually rotate the rotor which will open and close the points which should create a spark. Do not hold the coil lead to check if it's working as you will be the recipient of a very eye opening event. Another way is to simply pull a spark plug and with plug wire attached place it on the engine or other metal part making sure it has good contact with that part and turn the engine over as if to start it. You have to be able to see the electrodes of the plug because you will be watching to see if there is spark when the engine rotation gets to the point where that plug should fire.

 

[jhjacobs]

You can use most any coil as they are all basically the same. Some have internal ballast resistors and some don't. The stock coil on the E9 needs an external ballast as does the common Bosch Blue coil. I run a Bosch Red coil which has a built in ballast. If you measure the resistance across the coil + and - terminals and it is 3-4 ohms you normally do not need a ballast resistor. If the resistance is higher the coil may be bad. If it is lower you will need an external ballast resistor. Ballast resistors are normally between 0.5 and 1.5 ohms. The ballast resistor is a small ceramic device with two terminals; it is wired between the +12 and the + side of the coil. As mentioned earlier, the ballast is not critical for short term testing; it's purpose is to keep the coil from burning up.

If you think you have the timing set about right and the car won't start there could be many causes:

1. Are the points gapped properly - 0.014-0.16" if I remember? They should open and close as the distributor turns. They should also have a very low resistance (<<0.1ohms) when closed. If they are old points they can be burn or corroded. The point should have a small dab of grease on the part which rides on the distributor shaft but it is also very important to note that points HATE grease of any kind on the contacts.

2. Is the wiring correct?

+12 to ballast(a), ballast(b) to (+) coil lead -- you should see +9-12V at the coil (+) terminal when ignition is on.

(-) coil lead to condensor / distributor and from there on to the points inside the distributor.

Coil center to distributor cap center.

Plug wires in proper order and direction 153624 clockwise.

3. Are you getting any spark - I sometime take a sparkplug wire and plug it directly into the coil, install a plug into the plug side, wrap wire around the threads of the plug and ground the other side the write - you should see sparks when cranking (best done in dark). If there is no spark you need to look at the points again.

4. Is the rotor ditributing spark to the individual plugs? Same trick as above with a single plug wire from the distributor.

5. If this all works but it still won't start, either the timing is off by more than 25 degrees or you have a different problem

6. Other problems to check in a reasonable order:
--- Is the engine seriously flooded from trying to start unsuccessfully? This should show up as a wet black plug.

--- Are you getting fuel? As wet plug after cranking is a good indicator.
--- Do you have compression? Run a compression test.
--- Is the valve timing correct? This requires the valve cover being removed to check.