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no spark on 396 chevy

 
david1962
I love my Chevy Chevette!
Posts: 2
Joined: 04/12
Posted: 04/01/12 12:49 AM

no spark on 396 chevy motor  

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david1962
I love my Chevy Chevette!
Posts: 2
Joined: 04/12
Posted: 04/01/12 12:51 AM

396 chevy motor has no spark at distributor  

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idrivejunk
I mow my lawn and find Chevys
Posts: 5119
Joined: 12/09
Posted: 04/01/12 06:12 AM

Nice sentence. Is it a question?  
idrivejunk

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tuffnuff
Moderator
Posts: 7841
Joined: 12/09
Posted: 04/01/12 08:01 AM

Trace the ignition wire back to it's source.,. until you find the problem.

Smile  
When The Flag Drops.,.

tuffnuff

The Bull ***t Stops.,.
tuffnuff

P. Engineer, Engine Builder

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pepsi1
I mow my lawn and find Chevys
Posts: 1718
Joined: 09/11
Posted: 04/01/12 08:35 AM

Yeah happy days ....Boy oh boy Tuff man when a man can't find his hand in the dark it's time to switch to Ford....ooooH

Do what Tuff said bud and you will find the the problem
Bob  

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waynep71222
I have an SS396 tatoo
Posts: 448
Joined: 03/12
Posted: 04/01/12 12:35 PM

lets go over the Point type ignition systems found in chevys that had 396 engines installed...

there will be a resistance wire from the bulk head connector to the positive side of the coil.

there will be a second wire on the positive side of the coil that goes down to the R terminal on the starter motor solenoid...


when the key is in the RUN position..   the Ign 1 circuit from the ignition switch is run through this resistance wire to reduce the coil primary voltage to extend the life of the coil and points..  so there will be 9.5 to 10 volts on the positive side of the coil when the key is in the ON position...

now.. the IGNITION BYPASS circuit.. actually the ignition RESISTOR bypass circuit..

when the starter is NOT engaged... the hidden contact of the R terminal on the GM starter motor is NOT connected to anything..

when you turn the key to the CRANKing or START position..  the solenoid pulls the plunger back to engage the starter drive.. as that happens the plunger hits the button at the back of its bore and shoves the CONTACT disc under the solenoid cap out and bridges the heads of the brass bolts to send power to the starter motor making it spin ONLY after the gear is engaged in the flywheel...    this contact disc also touches the flexible contact of the R terminal .. sending  battery voltage for the ignition bypass circuit..

this sends power up the bypass wire to the coil to increase the voltage to the coil for a HOTTER spark for easier starting..    


lets look at the POINTS in the negative side...

with power to the positive side of the coil...   when the points are closed..  electrons flow from ground to complete the circuit of the primary windings in the coil..  this creates a magnetic field..

when the points OPEN.. the field collapses..  this collapsing field creates a HIGH voltage spark as the lines of magnetism break the secondary windings inside the coil..

if the points have worn contact faces.. you may not have enough contact to saturate the coil primary to create a spark when the points open again..



ok...   you kinda get the basic idea...   do you have a test light????  

Image 17623

hook the CLIP to the positive terminal on the ignition coil...    shove the probe into something to ground it to the engine block..  

turn the key on..   do you get a medium bright test light????  yes or no????

crank the engine..   do you get a BRIGHT test light???   yes or no..????


if YES to both..

disconnect the wire to the negative the side of the coil at the coil...

again.. hook your TEST LIGHT CLIP to that disconnected ring terminal.. make sure its not touching ground..    stick the probe of the test light onto the POSITIVE battery post.. or the output terminal of the alternator..  have somebody crank the engine..   the test light should FLASH BRIGHTLY..  

does it FLASH. yes or no.. ?????  if it does NOT time to look inside the distributer cap ..

for worn out points..  for loose wires where the wire to the coil connects to the points..  for broken wire between the vacuum advance screw and the points mounting screw..  

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waynep71222
I have an SS396 tatoo
Posts: 448
Joined: 03/12
Posted: 04/01/12 12:38 PM

there is a LOT more to testing and adjusting the point type ignition system..

but it requires more info from you as to what you have..  

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