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Q & A: Overdrive, Electronic Ignition

John, After reading more, do I have a ballast in the wiring? I read some notes about "a ballast in the wiring system before the coil". If so I believe I should have gotten a 6V reading. Also, if it makes a difference I took out the seatbelt cutout a long time ago, and I am getting fuel and I hear the fuel pump ticking occasionally.

Thanks again,
Steve Sharpe

John,

I am stumped. M 75 B will not start. It cranks strongly but does not fire. I have the Crane electronic ignition mod and an earlier distributor (about '72) but otherwise the electrical system is pretty much standard. A couple weeks ago I had this problem but at that time my son had left the ignition on all day after not being able to start it on a cold morning (inexperience I'm sure). He had drained the battery so I charged it up overnight and it still wouldn't fire. I thought I remembered that leaving the ignition on could fry the coil so I switched in a new Lucas (gold) coil. It started immediately, so it seemed that this solved it. We took it for a 2 hour roundtrip last week and it worked great, starting immediately several times. This weekend it wouldn't fire at all again. I checked spark at the plug and got nothing. I checked the HT spark from the coil to the block and got nothing. I checked battery voltage to ground at the battery and from the brown wire at the fusebox and got 12V each place. Following the Lucas Fault Diagnosis book I checked coil Primary circuit by going from the + terminal on the coil to ground with the "distributor contacts closed" (in this case the disk in the distributor is in position to that blocks the light, i.e. not on a lobe on the distributor cam) and got 7.5 V instead of 12V. At that point the Lucas book said this indicated a fault between the battery feed and the +terminal and to check the circuit back to the supply. Could you give any suggestions as to likely culprits to check? I have the wiring diagram but I am confused as to how this could happen.

Separate issue. Last year I rebuilt my LH overdrive at your February course and am going to install it in my 72 GT renovation project next month. I can't find my note but I believe you said that 1. the driveshaft and engine backplate should be okay as is. 2. The only thing I need to change on the car is the speedo drive. Is that correct and what new part should I get for that?

Thanks for any help you can give me on these. Hopefully I'll have both my 75 Roadster and the 72 GT at Cleveland. See you there.

Steve Sharpe

STEVE!

The overdrive first! The OD has either 1280 or 1000 gears for the speedometer. White gears are 1280; Red gears are 1000. Yet, if it doesn't work out, then you must only change the speedometer in the dash to the other... read more