HEI Conversion - Impala Tech
Electrical & Wiring Troubleshooting electrical problems

 
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post #1 of 7 (permalink) Old 05-14-2018, 05:14 PM Thread Starter
 
 
Join Date: Nov 2017
Location: SE PA
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HEI Conversion

We are getting close to firing up our project and I’m trying to find a “key on/crank hot” terminal, there is one on the fuse panel marked “IGN” and I am getting 11.6 v key on and 10 v on crank. In pretty sure this terminal has the white cloth wire on it. Is this the wire that needs to be replaced to give me higher voltage on crank/start. If so how does one go about removing this wire out of the fuse panel as I have never done this before.

Or is there another/better place to pick up the voltages I need?

Dan


1968 4 dr Impala
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post #2 of 7 (permalink) Old 05-14-2018, 11:57 PM
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The factory runs points ignition at 8 volts for two reasons. First it makes the points last longer. Second reason is when the starter more is drawing the 230 Amps that it requires to turn over the car's engine the voltage drops down to about 8 volts from the battery's nominal 12 volts. This way there is still enough voltage to fire the plugs.

You can tap the voltage right at the starter relay by tapping into the "R" terminal as it is energized hot when cranking, but not when the ignition is placed in the run (on) position. The factory uses this terminal to jump full battery voltage to the points because as you have noted the voltage in the car when starting and running is lower than the battery due to resistance of the wires.

Big Dave
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post #3 of 7 (permalink) Old 05-15-2018, 06:26 AM Thread Starter
 
 
Join Date: Nov 2017
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I’m a little confused, if I tap into the “R” terminal wouldn’t the car fire when cranking then shut down when the key went to “On position.

Dan


1968 4 dr Impala
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post #4 of 7 (permalink) Old 05-15-2018, 10:33 AM
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The S terminal starts the motor (engages the solenoid) the R is activated when the starter motor is energized.

You will occasionally read where some one complains of their car cranking up but the motor dies as soon as they let go of the key once it starts up. This is because they have no ignition power to the coil but the starter motor is energizing it when starting the car.

Big Dave
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post #5 of 7 (permalink) Old 05-15-2018, 12:11 PM
BA.
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When I did my HEI upgrade, I replaced the wire that goes from the bulkhead connector under hood to the (?). It was resistive wire.
I did not replace any wires under the dash area. But I did run a new hot lead 2 the distributor.
I think I made a thread on it here.

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HOW A NOVICE REBUILDS A 66 IMPALA CONVERTIBLE:
http://www.impalas.net/forums/blog.php?u=1432
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post #6 of 7 (permalink) Old 05-15-2018, 01:47 PM Thread Starter
 
 
Join Date: Nov 2017
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Quote:
Originally Posted by BA. View Post
When I did my HEI upgrade, I replaced the wire that goes from the bulkhead connector under hood to the (?). It was resistive wire.
I did not replace any wires under the dash area. But I did run a new hot lead 2 the distributor.
I think I made a thread on it here.

Sent from my XT1254 using Tapatalk
That is what I’m thinking about doing. The bulkhead connector in engine bay under their wiper motor, how does this come out? Take boltout of center and pull towards front of car. I removed bolt and connector wiggles a bit, but just doesn’t seem to wanna come out.

Is there a wire I could tap off of on ignition switch to accomplish powering the HEI.

Dan


1968 4 dr Impala
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post #7 of 7 (permalink) Old 05-17-2018, 08:44 AM
BA.
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Quote:
Originally Posted by 68impsed View Post
That is what I’m thinking about doing. The bulkhead connector in engine bay under their wiper motor, how does this come out? Take boltout of center and pull towards front of car. I removed bolt and connector wiggles a bit, but just doesn’t seem to wanna come out.

Is there a wire I could tap off of on ignition switch to accomplish powering the HEI.

It's been awhile, but I think you are correct on the disassembly with the caveat being that it has a weather-sealing tar-goop all around it and it makes for a super-tight, sticky fitment.

I may have used either a bit of a razor blade on the sides or a screw-driver to give a little assistance to prying it off.

HOW A NOVICE REBUILDS A 66 IMPALA CONVERTIBLE:
http://www.impalas.net/forums/blog.php?u=1432
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