Mallory Unilite distributor
 

Hey guys,
Yesterday my car stalled stranding me and my daughter on the way to the cruise. An intermittent problem that got real bad. 390FE, it has briefly stalled but recovered twice before where it would die for a few seconds then come back to life while coasting or idling along. Yesterday I hit the freeway off ramp and it just died. Tried to restart with no success. After 10minutes it restarted much to my delight and so I continued the drive back onto the freeway. Cruising along just fine for about 7 miles then it died again stranding me along side the freeway. After 10-15 minutes it restarted and I headed home very gingerly without issue.

Fuel is good, sight windows on the float bowls are both midway, fuel filter is clear. I figure it must be ignition starting to go bad. Mine is 13 years old but I have heard the Unilites go bad frequently. I went to get parts for my distributor and was told the Mallory parts are discontinued and I would be lucky to find them. Cap, rotor, resistor not available but he did have a new module. He suggested I get a new distributor all together and offered to test my MSG 6AL box. The one he showed me is taller than my Mallory, i'm not sure it will fit under my air cleaner.

What distributors are you guys running that fit? I have the long oval Cobra air cleaner, Edelbrock RPM manifold, flat tappet cam.

Do you have any other thoughts about a diagnosis?

Thanks for the help.

John

I would start by insuring you have a good ground(s). It is surprising how many times issues like this can be remedied with a ground strap.

Sounds heat related. I would test the MSD, then check coil (is yours bolted to the head or the inner fender?) and then the distributor pickup.

Thanks for the tips. I will look into these items. I will follow up on my findings.

John

i'm not a big fan of either mallory or the msd dist's.
i had a Ford duraspark recurved and i use that with a msd 6AL box

Holley owns Mallory they carry the complete line The modgual is replaceable about 40 bucks takes ten minutes to replace, the item comes with complete instructions

Module, sorry

The Mallory Unilite uses an optical triggering system. The problem with that is as the engine runs there's some ozone creation inside the distributor cap. The ozone tends to "plate" out on the distributor's optical sensor over time. This continues until the generated optical light can't make it to the sensor. At that point you'll start to lose triggering and engine firing. Try cleaning your optics with some denatured alcohol. I had this problem many years ago with a Unilite myself.

Follow up-
I replaced my module for the Mallory Dist., replaced the coil, checked all connectors insured I was getting a good ground, charged the battery while it was disconnected. Car started right up. I drove it about 7 freeway miles, engine is running great until Iam cruising along the off ramp under light acceleration and it died. I got the ride of shame home inside a tow truck. Guess now I will replace the MSD. Also this time there is no restarting after a cool down. More to come....

John

When it dies to you have spark?

Are you using a power filter SUM-830440 if not you should and they do go out, also are you using a resistor going to the coil? Just my 2 cents

Mallory Unilite distributor and coil needs resisted 12V for normal operation. If you are using the Mallory HyFire box, The box takes care of dropping the power. Full 12V for starting resistor bypass on starter solenoid then drops voltage down for normal operation Mallory has a shorting plug that eliminates the BOX, I keep mine in the glove box. I had a newIgnition box go bad .It would idle in the alley just fine. I drove the car and it started running like crap. but would idle just fine but it wouldn't leave the stop light. It got so bad I was happy to get back home. I used the shorting plug and swapped to a resisted power source and it ran just fine. I blamed the HyFire IV box. It was still under warranty so I sent it back and ordered another HyFire IV box and it didn't have any problems.