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Balast Resistor?

mike mac

Jr. Member
Joined
Jul 31, 2007
Messages
147
Loc.
Daly City, CA
How do I know if I need a balast resistor. I have a pertronics flame thrower and Holly 2D TBI. I can't seem to get it all working properly since adding Painless wiring harness. Seem to found a wire discrepancy in the harness info but can't seem to figure it out. Don't seem to get proper spark.
 

spatacuulous

Full Member
Joined
Mar 21, 2005
Messages
169
Loc.
philadelphia
The flame thrower takes 12V from the key when it cranks. On the original Coil, it only took 6V. Thats why we have the ballast resistor inline in the original. I have the Petronics flamethrower too and completely eliminated the ballast resistor. It just doesn't need it. It's totally capable of handling the full 12V. ;)
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,275
Pertronix does still make some coils that take a resistor, but hopefully yours is one of the full-voltage kind. Check the label to see what it says. Or get the part number and ask Pertronix to make sure.
But I'm with spatacuulous, you probably don't need one and the Painless most likely is running the full voltage. And you wouldn't need one just to get the thing running and test for spark anyway. The reduced voltage of a resistor is just to help the older coils last longer. Even an old original coil would still spark with 12 volts.
A coil that doesn't use one has an internal resistance that's compatible with 12 volts and will sometimes list that value on the label.

What's the actuall problem you're having? No spark at all? Erratic spark? You didn't mention what exact ignition system you're running. Electronic or points? Factory or aftermarket? Or is there a Flamethrower ignition system and not just a Flamethrower coil?

Paul
 

chuck

Bronco Guru
Joined
Aug 14, 2001
Messages
6,474
Loc.
Ingram, Texas
The 6v coil is .3 ohms, the 12 volt is .6 ohms. Turn the ign. on and check the voltage at the coil (+) The coil mist be hooked up grd the (-)
The above is all wrong, What I was trying to type is with the resistor the 6v coil will read 3v and the 12v coil will read 6v.
 
Last edited:
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mike mac

mike mac

Jr. Member
Joined
Jul 31, 2007
Messages
147
Loc.
Daly City, CA
I get it to crank but won't turn over and it seems to be draining battery. It started and ran right after install but then just died and hasn't run since. Coil got hot during cranking. Also it gets close to running but dies after starter disengages. I have the Pertronics pick ups only and just an over the counter coil. It also has a '95 f150 alternator but all run well before Painfull/less. It does seem to get a speratic spark but just tumbles if that makes any sence.
 
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mike mac

mike mac

Jr. Member
Joined
Jul 31, 2007
Messages
147
Loc.
Daly City, CA
FOUND IT! Wrong wire to Holly Pro. No current at run. Called Painless and they talked me through just fine. Thanx to all.
 

68ford

Bronco Guru
Joined
Dec 26, 2004
Messages
2,710
The 6v coil is .3 ohms, the 12 volt is .6 ohms. Turn the ign. on and check the voltage at the coil (+) The coil mist be hooked up grd the (-)

6v is1.5 and 12v is 3ohms.
 

mudstud

Contributor
Bronco Bonehead
Joined
May 19, 2005
Messages
1,504
Interesting question. I have tried to start my rig with no success. There was no fire to the plugs. The plugs and plug wires have been replaced. I checked the voltage to the coil. The reading was 1.4 volts. The rig has been setting for seven years. When it was parked, the engine ran fine. Could the resistor be bad or should look somewhere else? Sorry for the hijack.
 

chuck

Bronco Guru
Joined
Aug 14, 2001
Messages
6,474
Loc.
Ingram, Texas
Put a jumper from the battery (+) to the (+) side of the coil and try to start it. Its no problem to have 12v to the coil for a short time. If it starts start looking for bad connections from the ign. sw to to coil.
 

mudstud

Contributor
Bronco Bonehead
Joined
May 19, 2005
Messages
1,504
Thanks, it turned out to be a bad ignition module.
 
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