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I am in the process of swapping my original points and coil system to an HEI system. I have read a few things about having to deal with a resistor wire for the HEI to work. I have around 11.9v at the battery (which is a little low) and 11.6v at the hot wire that would have connected to the old coil in both the run and start position. Is this enough for the HEI system.
Important note: I do not have the HEI system right now it is on its way.
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Originally Posted by Logan B
I am in the process of swapping my original points and coil system to an HEI system. I have read a few things about having to deal with a resistor wire for the HEI to work. I have around 11.9v at the battery (which is a little low) and 11.6v at the hot wire that would have connected to the old coil in both the run and start position. Is this enough for the HEI system.
Important note: I do not have the HEI system right now it is on its way.
A real HEI will work down to six volts. What it can't deal with is resistance in that feed line. Were you making those 11.6v readings on the original coil feed line (open circuited)?
A real HEI will work down to six volts. What it can't deal with is resistance in that feed line. Were you making those 11.6v readings on the original coil feed line (open circuited)?
I believe so, I took the old distributor and coil out and then used the wire that would’ve connected to the coil. Using a multimeter with the red on the old coil connection and then grounding out the black it read 11.6v.
So an answer AND an explanation. That wire will probably be OK to power your HEI.
A fully charged battery is 12.6 or above. 12.3 is 50% discharged. So your battery is very, very low right now.
Back in the day the coil would be energized by two wires. One comesoff the starter, so whenever you CRANKED, the coil got the full battery voltage. Mind you, battery voltage might droop to 9V or less while cranking. You wanted the maximum spark you could get.
Now while running, a coil energized by full alternator voltage (13.8) will disintegrate the electrodes on spark plugs. Literally evaporate them.
So while running (not cranking) the coil got powered by the battery THROUGH what's called a "ballast resistor". It served to lower the voltage to where your spark plugs didn't disintegrate in 500 miles or less.
I once disintegrated a set on an old Subaru running a big yellow ACCEL coil right off B+, lol!
So you need to figure out if there's a ballast resistor in there somewhere, mounted on the firewall, whatever, and wire around it. Or just take any IGN feed to run your HEI. Often they're square shaped.
HEI will have no trouble taking full alternator voltage while running.
So an answer AND an explanation. That wire will probably be OK to power your HEI.
A fully charged battery is 12.6 or above. 12.3 is 50% discharged. So your battery is very, very low right now.
Back in the day the coil would be energized by two wires. One comesoff the starter, so whenever you CRANKED, the coil got the full battery voltage. Mind you, battery voltage might droop to 9V or less while cranking. You wanted the maximum spark you could get.
Now while running, a coil energized by full alternator voltage (13.8) will disintegrate the electrodes on spark plugs. Literally evaporate them.
So while running (not cranking) the coil got powered by the battery THROUGH what's called a "ballast resistor". It served to lower the voltage to where your spark plugs didn't disintegrate in 500 miles or less.
I once disintegrated a set on an old Subaru running a big yellow ACCEL coil right off B+, lol!
So you need to figure out if there's a ballast resistor in there somewhere, mounted on the firewall, whatever, and wire around it. Or just take any IGN feed to run your HEI. Often they're square shaped.
HEI will have no trouble taking full alternator voltage while running.
Cheers!
From the research that I did, I found that in 73' they switched to a resistor wire instead of the box. But I have not been able to find the resistor wire. Does anyone know where it might be located?
Also, the previous owner of the car wired an aftermarket radio into the IGN slot, so unless there is another way to power the radio I don't think I can use the IGN slot.
so leave the resistor wire alone and run a regular wire from the ign terminal. but best bet is clean, gap the points. set the dwell and timing. the problem with points is on daily drivers with no maintenance the rubbing block wore until the points didn't open. i had a friend junked his car cuz he didn't know he need to do a tune up.
i used to set people's points on the side of the road when i heard them cranking the engines for 10 seconds to get it to start.
So an answer AND an explanation. That wire will probably be OK to power your HEI.
A fully charged battery is 12.6 or above. 12.3 is 50% discharged. So your battery is very, very low right now.
Back in the day the coil would be energized by two wires. One comesoff the starter, so whenever you CRANKED, the coil got the full battery voltage. Mind you, battery voltage might droop to 9V or less while cranking. You wanted the maximum spark you could get.
Now while running, a coil energized by full alternator voltage (13.8) will disintegrate the electrodes on spark plugs. Literally evaporate them.
So while running (not cranking) the coil got powered by the battery THROUGH what's called a "ballast resistor". It served to lower the voltage to where your spark plugs didn't disintegrate in 500 miles or less.
I once disintegrated a set on an old Subaru running a big yellow ACCEL coil right off B+, lol!
So you need to figure out if there's a ballast resistor in there somewhere, mounted on the firewall, whatever, and wire around it. Or just take any IGN feed to run your HEI. Often they're square shaped.
HEI will have no trouble taking full alternator voltage while running.
Cheers!
The resistor wire is there to limit current through the points so you don't burn the points up.
I am in the process of swapping my original points and coil system to an HEI system. I have read a few things about having to deal with a resistor wire for the HEI to work. I have around 11.9v at the battery (which is a little low) and 11.6v at the hot wire that would have connected to the old coil in both the run and start position. Is this enough for the HEI system.
Important note: I do not have the HEI system right now it is on its way.
I have an msd tach drive, with msd 6al plus coil and msd wires low miles that I don't need
From the research that I did, I found that in 73' they switched to a resistor wire instead of the box. But I have not been able to find the resistor wire. Does anyone know where it might be located?
Also, the previous owner of the car wired an aftermarket radio into the IGN slot, so unless there is another way to power the radio I don't think I can use the IGN slot.
I believe the resistor wire comes out of the back of the fuse block and if memory serves it is pink in color. The previous owner of my '73 installed an HEI distributor but connected it with the original resistor wire. The car ran okay but started misfiring and running poorly at high RPMs. I had the engine dyno tuned and the tuner found the problem. He replaced the resistor wire with a new one coming from the ignition terminal and all was well. It was very interesting to see the dyno graphs before and after replacing the resistor wire.
I believe the resistor wire comes out of the back of the fuse block and if memory serves it is pink in color. The previous owner of my '73 installed an HEI distributor but connected it with the original resistor wire. The car ran okay but started misfiring and running poorly at high RPMs. I had the engine dyno tuned and the tuner found the problem. He replaced the resistor wire with a new one coming from the ignition terminal and all was well. It was very interesting to see the dyno graphs before and after replacing the resistor wire.
DC
Do you know what they did with the original wires?
i would fold orig resistor wire back and tape it off. you could pop the HEI on a sunday morning when you had a get together to go to. if everything is there to refit orig it would be easier. and you may decide you hate the big fat cap and wsnt to go back to orig...
Someone added in a resistor on my 72 for some odd reason. I'm going to switch to a pertronix HEI and get rid of it. I have been told the original resistor wire is the one with the cloth wrap coming through the firewall plugged into the left side of the resistor.
That resistor wire is white with a fiberglass like cloth covering. Leave it but just don't use it. I believe that it comes from the ignition switch. At least it does on my 68. Lou.
1973 Corvette HEI swap.
