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** Rollback Ride For My 56

2K views 24 replies 7 participants last post by  hotrodg726 
#1 ·
Ignition system took a dump Friday night. I had to be towed home from Friday Night Thunder in Inverness Florida.

Did a bunch of testing Saturday morning. Several of my friends came over to the house. No spark. No 12V to the + side of the coil.

I had just had the Unilite out about 2 weeks ago to have a new vacuum advance installed, and have it set up on a Sun Machine. The module was dated 1990.

We could not get 12V out of the MSD box either...

Pulled the Unilite... tried it on the Sun Machine... and the module is fried. Now, we're not sure ..... YET if both the MSD box AND the Unilite module fried.

I ordered a new module. I found a MSD wiring diagram on the internet. My buddy is coming over this afternoon, and we're going to test the MSD again,
now knowing that the Unilite module is DOA.

If it's OK...I'll just put the Unilite back in with the new module. If not, I have a friend who is "gifting" me a small body HEI distributor and matching coil. I'll tear out that entire MSD box and ditch the Unilite.. and run with the HEI..

I have driven cars for 55 years... and this is/was the first time in my life that I ever broke down on the highway... and needed to be towed home...
 

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#2 ·
No spark. No 12V to the + side of the coil.
......We could not get 12V out of the MSD box either.....
...
If you don't have 12 volts to the + side of the coil or MSD, in run and start, it's not an ignition system problem. It's a ignition switch or wiring problem. Check the connectors on the ignition switch.
Try hot wiring the coil with a jumper from the battery.
 
#3 ·
We had 12V TO the MSD.... just not OUT of the MSD.

After finding that the Unilite module was "toast" on Saturday afternoon, I ordered a new Unilite module from Speedway on Sunday. It's "in the mail"...

After finding a wiring diagram online, we tested the MSD box about an hour ago, and the box is working.. so it was not being triggered by the Unilite, which is a photoelectric cell apparatus.

The Unilite is out of the car, still clamped in my buddy's Sun Machine...

No way to do any further testing... until the module arrives.

Thank you for your input.
 
#5 ·
throw away unilite get a msd distributor set the curve in it as you want it plug into msd box and forget it. with an msd box you will not have 12v at the coil with key on engine off. you should have 12 at the small red wire into the box with key on ignition off though.
 
#7 ·
Nice rig. :D

It's an International... with a Cummins diesel and an Allison auto trans.

Full crew cab.. impressive inside.

Driver said it would haul 25,000 pounds...

Adam's Towing has nice equipment. There are a ton of old cars in the county where I live. My cruisers club has 300 members, who own probably 500 cars. Then, there are several other "old car" clubs..

Adam's is the "go to" place. They're local, respectful, careful, and timely.

The driver told me he probably hauls one antique car per week out of some venue. :D.

https://www.adamstowingandrecoveryllc.com/
 
#8 ·
With an MSD box, the coil doesn't take power from the car electrical system, as do coils from points and point replacement systems, they fire off the ignition box.

We found that what our ignition tech said was dead on true, and have fixed more than a few Unilite ignitions by doing what he outlined to do.

Unilites were never designed to run on a full 12 volts, they are designed to run between 6.5 and 9.5 volts, and most people buy into the erroneous info that force feeding them more volts, raises spark energy. It doesn't, all that happens is, they go blind.

The ignition tech has a few distributor machines, and so do we, both of us have set up a machine to do Unilite service, and we do exactly as Mallory says to do, run a Unilite on a dry lantern battery on the machine, 9.5 volts, NO MORE.

There was a reason Mallory put the .60 ohm MOPAR resistor in with the Unilite, it was to be added between the stock resistor in the car, and the positive wire to the Unilite, to drop the input volts down to the 9.5 volt level.

In the 20 plus years we have been dual ballast resisting Unilites, not one of them done that way have failed, and when tested on our scope, we find them to not make one volt less than one force fed to a full 12 bolts, nor only single resisted, no matter the coil used. They were never designed to raise spark plug voltage, just be a great ignition system, when resisted right.

It also didn't hurt knowing Boots Mallory as well, our ignition tech and I knew Boots for a long time before he died. Boots never ran a Unilite without two resistors in the feed line, stock and .60 ohms.

But, all you guys keep on doing it the over volt way, enjoy the Unilite failures.

Willard Thompson
 
#10 ·
Interesting...

The module in my Unilite was dated 1990..

The motor in my car was built in 1992. It has had 16,000 miles put on it in that 26 year period...

I did not install this Unilite, nor did I build this motor. It does have a MSD 6AL box... that is also 1992 vintage.

I did not know about the inline resistor or resistors... I will investigate. I have a new module coming from Speedway. It's in the mail...

I also have a small body HEI coming... a gift from a friend... so I have options.

I tested the MSD box the other day, and it has power.. so I think that the box is OK.

I know for sure that the Mallory module is toasted...
 
#12 ·
I don't know yet. :D

A friend offered it to me.. I didn't ask. You can't look a gift horse in the mouth.

It supposedly came from a 62 Corvette, which was restored and converted back to the standard distributor and coil.

It should be here Thursday...
 
#13 ·
I still say use an msd distributor and be done with the unilite.
 
#14 ·
I agree, but not for the reasons some might think.

The Unilite, when the resistors are correct, isn't a bad ignition. Just like others, run them full volts, it is only a matter of time before they die.

The bad thing about Mallory is their mechanical advances are straight out of the stone age, and hard to access to set.

Willard Thompson
 
#15 ·
Update:

I'm back up and running with the Unilite. New module installed. The old one was dated 1990, so it worked for 28 years...

The Accel Street Billet distributor arrived.



I tried it in. Both the body of the distributor and the cap hit the firewall. It'll fit... but you couldn't slide a feeler gauge between the unit and the firewall

My buddy is checking the Accel on his Sun Machine as I type this.

Not sure if I can use it... or should use it..
 
#16 ·
If you are using side engine mounts and a trans cross member you could shim up the trans mount 1/8" and gain a bunch of clearance .
 
#17 ·
:( I'm not. Front mounts and "batwing" bellhousing mounts.
 
#24 ·
Just to finish this up, and dot the "i's" and cross the "t's"....

#1. I'm back up and running with the Unilite with a new module installed. The module that we removed was dated 1990, so it worked for 28 years before failing. :)

#2. I replaced both rear "batwing" motor mounts. They were sagging, and by doing so, I gained 1/2"+ clearance on the firewall. So, the cap clip that was digging into the firewall now has 1/2" clearance.

3. My buddy gave me an Accel Street Billet distributor. It's bigger than the Unilite. It needs some vacuum and centrifugal advance work, but it NOW might possibly fit.

4. I'm investigating small body Accel and MSD distributors, and will probably go that route.

5. I'm considering a transverse X member trans mount to use in addition to the batwings...

6. Final comment: :D

I had put new rear motor mounts in this car about 10 years ago, and remembered what a HORRIBLE job it was. Well, it was another tough operation this time . Why? The motor mounts, from Anchor Industries, marked DOAN on the box fit like boots on a rooster. They were marked "Made In Taiwan"....

I had to grind 3/16---1/4" off of the bottoms to get them to fit into the pocket recesses. I had to slot out the holes to give me some wiggle room to get them mounted. LT side was worse than the RT.

I don't know if someone makes a correct motor mount that FITS, but to call these mounts "reproductions", or "factory replacements" is a stretch.

Rant over. :D

Thanks to all for your help and your suggestions.
 
#25 ·
the cross member is cheap insurance
the msd distributor should be a plug and play deal with the msd box you already have.
 
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