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350 chevy vette missing

I love my Chevy Chevette!
Posts: 1
Joined: 10/12
Posted: 10/29/12 02:27 PM

I have 1975 c3 with 350 and electronic ignition ,I replaced the cap and rotor because it is missing . I can here a loud clicking inside the cap in # 4 cylinder.
Can anyone give me a hint as what is wrong .     thanks      clockdon Crazy  

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My first time was in a Chevy
Posts: 241
Joined: 04/12
Posted: 10/29/12 08:37 PM

there are a few issues in replacing HEI distributer caps..

did the ground strap get swapped over...  the what?? there is a folded metal strap with a hooked end.. fits under the coil hooks to the center wire of the 3 up from the distributer housing.. completes the spark return ground circuit.. without it.. you can actually blow the wires off the coil..

this is the ground strap that fits under the coil in the TOP of the cap...
HEI Largecapgroundstrap

you can see the 3 wire connector in this image..

you can see the ground strap between the red and white coil wires..


did the rotor get installed properly..  there is a square end on the top of the shaft that fits in the slot on the skirt of the rotor...

did the center spring contact get properly seated when the cap was dropped on..  so its not riding around the carbon in the center of the cap... instead of just behind held down by it so the electrons can flow nicely into it..

could one of the 8 terminals inside the cap be striking the tip of the rotor... if so.. the rotor won't last long...

this is an actual HEI coil that was installed and driven without the ground strap under it..

the installer actually went at far as cleaning the paint off the laminations so there was better contact through the laminations.. but leaving the ground strap out???  

Burnt Coil  

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My first time was in a Chevy
Posts: 241
Joined: 04/12
Posted: 10/29/12 08:55 PM

if there is a LOUD clicking inside the cap...

i would also inspect the spark plug wires...

do you have a digital volt meter.. with a 200K OHMs setting...   ohms settings are 200, 2k, 200K 20M..    200K will display less than 199.999 ohms..   measure your spark plug wires in this 200K setting...

your wire should display on the meter less than the length of the wires in inches..


if you have an 18" spark plug wire.. if its good.. it will OHM at less than 18,000 ohms...  it should display at that setting 10 to 15 on the meter...

i usually recommend that you remove the HEI cap.. flip it over.. leaving the spark plug wires attached..  and ohm  from the internal terminals  to the removed wire at the spark plug...

the coil high voltage will rise until it can jump to ground.. so you could have an open spark plug wire..  either not properly installed at the cap end..    not snapped on at the plug end.. the carbon inside the wire worn out ... or the MOST LIKELY reason... the wire terminal is actually pulled away from where it was crimped to the spark plug wire..  i have pulled spark plug wires and found that somebody yanked the end off at the spark plug.. and just shoved it back into the boot...  i have taken to OHMing the spark plug wires as described. .or looking up the end with a bright flashlight to verify the terminal is at the proper depth and the core wire is folded under and crimped in properly...

please verify that you also don't have any high voltage leaks through the sides of the HEI Coil..


you can see the dust pattern in this image... where the high voltage created by excessively high resistance spark plug wires caused the high voltage to work its way through the insulation..

COIL Highvoltageleakage  

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My first time was in a Chevy
Posts: 241
Joined: 04/12
Posted: 10/29/12 08:56 PM

please... let us know what you find..  

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