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Monster problem

I love my Chevy Chevette!
Posts: 1
Joined: 04/13
Posted: 04/18/13 02:35 PM

Hello all,
I have a 66 el camino with a 454 and hei ignition. Car runs great but once hot and shut off it will not restart. Will crank, good fuel pressure just no spark.
Best I can tell, is if the tach wire is disconnected from the cap, she will fire,or if left to cool down will fire?
What could,go wrong internally with the tach?  FYI, it is a 5" monster
Thank you in advance.
Spec, not that it matters lol, 66 elk custom, 454, turbo 400 with manual shift bodies, 12 bolt posi,  front disk, full tube suspention.  

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I have an SS396 tatoo
Posts: 251
Joined: 03/13
Posted: 04/21/13 05:07 AM

seems you have actually answered your own question... does it die while driving with the TACH disconnected??

the red wire is the BAT...

the white wire is the TACH.

but if you notice.. the white wire is also attached to the harness that goes down to the module C terminal
the red wire goes down to the B+ terminal on the module..
the center wire of the 3 going to the module is a ground for the black wire coming out of the coil.. this is the spark return path.


so... if the engine dies with the tach connected and does NOT die when the TACH is not connected.. then its more than likely a MONSTER TACH issue..  or the wiring between the HEI tach terminal and the monster tach is shorting out..

if the engine still dies with the TACH disconnected.. then we have to go farther..

remove the coil cover off the top of the cap...  stick a test light probe (pointed end) into one of the cavities for the red wire to the coil... be sure that you are not touching the center wire or the white wire...(sometimes yellow )   ground the clip end of the test light to the engine...

from the drivers seat.. turn the ignition key from the OFF position .. to the ON position .. then crank the engine .. and release the key back to the RUN position..  then turn it off..   depending on how you have wired the HEI...

you should have constant power as soon as the key reaches the ON position.. thru cranking and back to the on position..

if the light is medium brightness and then gets full brightness when you are cranking..  then goes to medium brightness in the on position.. then you are going to need to either use a relay or change your ignition switch to one that does not break contact with the IGN 1 circuit while cranking..  and remove the resistor wire.. replacing it with something slightly thicker.

this is something i worked up for in dash ignitions on GMs.. using parts store parts... this does require some slight rewiring .. but nothing major league..

Gmkeyindash POINTS To HEI

there are a few more tests for the HEI...

if the module is not screwed down on a proper layer of dielectric tune up grease... it will over heat and fail..  dielectric tune up grease a thermal compound.. it allows the massive amount of  heat created by the switching of the C terminal on the module to the ground ..  when the C terminal and the white wire are grounded . the current is flowing thru the primary windings of the coil...  when the module breaks the ground connection..  the magnetic field created collapses thru the secondary windings and creates a high voltage spark..   on a V8.. the module makes and breaks this connection 4 times per revolution of the crank..  

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