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454 ignition wiring

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76luhrs

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"1989 454 crusader,converted t

"1989 454 crusader,converted to new Pertronix billet marine distributers back in august. Started having issue with module failure in unit. Factory said to check voltage with coil grounded,should be at least 11.5volts. Found 8.6volts on mine (key on not running). Did Crusader use a resistor wire from altenator to the coil? Did not find a ballast resistor in line so far."
 
"I doubt that any resistor wir

"I doubt that any resistor wire was used by Crusader. I'd look at the voltage drop from the starter solenoid thru the engine connector, thru the wiring to the dash, ignition switch, then back to the engine connector, finally, to the distributor. Pay special attention thru the engine connector, i've seen voltage drop, just thru the connector."
 
"Do have a pair of 87 crusader

"Do have a pair of 87 crusader 454, there is a resitor and a by-pass 12 vdc from the selenoid switch on the stater to feed 12 volts direct to the coil when starting."
 
"Dennis:

I'm with Dave

"Dennis:

I'm with Dave on the checkout. The ballast resistor is usually located close to the main breaker, above the starter, on that vintage.

There is no feed from the alternator to the coil, only the key ffeds the coil during RUN. As Henry noted, there is an extra feed to the coil fromm the starter's solenoid that only supplies current during cranking."
 
"To be more clear, I was only

"To be more clear, I was only addressing a possible "resistor wire". That is a special, non-copper wire used as a resistor, but not showing as the typical, white, ceramic body coil resistor. On the alternator, some companies use a "fusible link" near the alternator. Again, I don't think Crusader used these either; both are $ shortcuts used in some cars.
If you do find a ceramic body resistor, put a short wire across it. That will raise the ignition system voltage to acceptable values."
 
"I think if your engine came w

"I think if your engine came with a Mallory dist. then you will have a resistor. If it came with the Prestolite (sp?), it didn't.

I could be wrong....."
 
Okay no resistor has been loca

Okay no resistor has been located. Went thru wiring harness from dash to engine. Main harness connection is clean and all connections at switch are clean and tight. Voltage measured at start switch is 13.2 volt and at violet wire at coil is 13.2 volt. When I connect the violet to the coil (+) and ground the (-) of the coil I only read 9.6 volts at the coil. I have twin engines and both are the same. Original distributors were Prestolite electronic. What would cause this voltage to drop ? Is coil resistance doing this ? (Flamethrower 0.6ohm coils)
 
"Dennis; Did you say that the

"Dennis; Did you say that the primary is 0.6 ohms? That's 12/.6 = 20 amps of primary current! Your drop to 9.6 is a result of 20 amps running thru 20 or 30 feet of wire and connectors. I'd say normal. I'll bet the stock coil has a higher primary ohmage, though I don't know the value. I'm running jacobs omnipak with built-in coil."
 
"Dave, original coils for the

"Dave, original coils for the Prestolites were 1 ohms. Pertronix said I needed to use there coils at 0.6 ohms for there units. They also say I need at least 11.6 volts at coil with neg. side grounded. Voltage measured at the end of curcuit is 13.2 volts. When I connect hot to coil it drops to 9.6volts."
 
"Dennis:

Dave's use of

"Dennis:

Dave's use of Ohm's Law is very reasonable, especially given the age of the wiring.

Either way, I wouldn't leave the hot wire on the coil any longer than needed to take the measurement as that is a 100% duty cycle, w/o the alternator helping.

I'd check the battery's charge and make sure it is 'full'.

you can eliminate any voltage drop in the existing harness by temporarily jumping the coil to the battery lug at the starter. Use a heavy gauge wire (#14 or bigger) preferably with a fuse."
 
"One fix for this is to put in

"One fix for this is to put in an engine mounted ignition relay. You will not otherwise be able to reach 11.6 at the coil, engine not running, coil full "on".
As reference, my port side Prestolite ignitor went out this year after 26 years of service. I replaced the stb side because the case was so corroded. This things should really go near forever. "
 
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