HELP! Mallory Unilite Issue

SBC, Mallory Unilite, Generic Coil, Generic Ballast Resistor, Generic Wires.

Engine ran fine with that combination, had a slight miss, but has been wired & running this way for years with no issues. Decided to upgrade the Coil/Resistor/Plug Wires

Got a new Mallory Chrome Canister Coil, Mallory Ballast Resistor, Accel Spiral Core Wires.

I pulled the truck into the shop and swapped the plug wires, swapped the coil and the ballast resistor. No changes were made other than directly replacing these parts.

I started the truck up, it ran for a split second. Since I didn't blip the throttle, it died. I tried to start it back up and now it just cranks like its not getting spark.

Coil is showing 6.51 volts at (+)POS with Ignition ON and 6.53 volts at (-)NEG.

What the hell?

 

Here's how you test the photocell http://www.malloryperformance.com/pdf/UniliteTest.pdf
My '73 Harley sits a lot & this week when I decided to go for a ride it wouldn't start. The unilite took a crap

 

OK, WTF!?

I popped the cap & rotor to test the Unilite Module. At the NEG coil terminal I'm now getting 12.49 Volts. So I put the credit card in front of the Optronic Eye and it says 1.25 Volts....right on.

I double, triple check this. I didn't touch anything else during this voltage test. Pop the cap back on, crank the truck....vroom...runs. WTF? So I double, triple check everything again...now it's all checking out fine. Weird.

I've got to go about 60 miles south of here in about an hour. Hope this was just some sort of a fluke and doesn't leave me on the side of the road.

 

1957, thanks for the link, but I've got that module test imbedded in my brain after chasing this weird erratic slight misfire for the past couple months. As of today the Module is the only thing I haven't replaced on the entire ignition system.

Everything seems fine now. But I'm kind of weirded out.

 

I bought my first Unilite in the seventies & that has happened more than once to me. I have three right now stored in the garage & won't use them unless it is with a tunnel ram or a blower with clearance issues

 

You didn't happen to see a moth or bug fly out from under the cap when you popped it off, did you?

 

Ebb, haha, nope. I just had the cap off the 2 days ago to test the module, clean the cap & rotor, replace plugs and rebuild the 2-Jet. Put about 150 miles since then.

 

Update: All is well. Did 120 miles on the highway tonight, not even a hiccup. Don't know what was going on.

 

I've been running a Mallory Unilite for over 16 years.The only issue I ever had was when I replaced the cap and rotor with Mallory parts,turned out after some run time it quit.I took the cap off and the distributor was full of shavings,the tang on the rotor was too long,shaved the cap terminals off into the base.Cleaned it up,put the old cap and rotor back on and hit the road!!! ROY.

 

make sure the ground connection is clean and tight. And carry a spare module with you.

 

Make sure your Unilite is grounded to the engine block per a Mallory Tech when I had a similiar problem.

 

I know that this is an old post, but I didn't feel I should start a new one with a similar problem. I am running a Unilite in my '51 (w/SBC) and my problem is that I ran it for awhile, took it out when doing some work on the motor, re-installed it, and now the car just cranks and will not start. Anyone have some answers for me? Thanks in advance.

 

Sounds like you have got a bad connection somewhere. You should be getting 9V to the positive side of the coil when it is running if that helps.