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1971 GTO Positive Battery Cable for 400?

10K views 37 replies 9 participants last post by  Montreux 
#1 · (Edited)
1971 GTO 400 Positive Battery Cable having a hard time finding SIDE MOUNTED one. Most options say they only work for 455 motor. Anyone know a vendor and/or how many inches is the cable so I can have one made. Or a picture of one??
 
#2 ·
I made my own and incorporated some design improvements along the way.

Pick the gauge you want - most will say 4 ga. is fine, but you could go with 2 or 0 -- all sold at any auto parts store by the foot.
 

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#3 ·
Thanks for the picture. I was hoping there would be a very specific one that would be like the original factory one. The car I am working on did not have any of the accessories, cables, etc. Only the engine. It looks like you have a solenoid between the starter and the battery---is this original??
 
#5 ·
This is not original, but makes the car much safer as the cable to the starter is ONLY hot when cranking. Also I purchased a battery with the poles in opposite position as I did not want to have the positive terminal so close to the fender. The other wires have fusible links so there really is no chance of an electrical fire.
 
#7 ·
Have not ran across '71-72 side terminal cables properly reproduced. Aftermarket positive cables that are close in length as well as GM service replacement positive cables avail in the 80's & 90's & now sold on eBay as "nos", LOL, have a small lead that comes out of the molded side terminal end.

Length wise, the side mount negative cable is the exact same as used on a '71-72 B series with 455. The '71-72 side mount positive cable is slightly different length than the one used in the B series chassis, am watching for the box with several of these original cables. On '71 & 72 455 HO A-bodys, the positive cable is routed differently, through clips that parallel the bottom of the block versus typical Dport deal where there is a vertical tube to route the positive cable down to the starter solenoid. this routing also contributes slightly to the length. Def the way to go if running RA manifolds.
 
#12 ·
Yes, the Pontiac starter already has a solenoid as do all GM starters. A Pontiac starter can experience what is called "heat soak" due to the position of the solenoid near the exhaust manifold or headers. You can shield the solenoid with an aftermarket aluminum shield that fits/bolts over the solenoid to help keep heat off it.

Often heat soak can also be due to too small of a battery cable wire gauge size, especially when replacing with store bought cables which can be a smaller gauge than needed. You want a "2" gauge or "0" gauge cable.

Any form of corrosion will create additional resistance and the solenoid may not get the needed amps to crank the engine as well as it would when cold. The corrosion can build up inside the casing/wire even though it looks good on the outside. This includes the Purple wire that runs from the ignition switch to the "S" terminal lug on the solenoid.

Improper timing or even high factory compression ratios will make a starter labor when the engine is hot. It is not a starter problem, it is a timing/compression problem.

The Ford solenoid is a fix that some like to use and add to the starter system. I am a little ignorant on just how this works because you still have to run a battery cable to the GM starter solenoid which is what kicks in the starter gear that spins the engine.

I would not wire up a Ford solenoid. Just does not look clean and you have to run wires. And it is too easy to jump and steal your car.
The other alternative is to use a mini starter which allows you to rotate the solenoid away from the exhaust manifold - like the RobbMc mini. It also has more torque to crank the engine faster.

Here is a discussions in using the Ford solenoid.
 
#13 ·
Yes, the Pontiac starter already has a solenoid as do all GM starters. A Pontiac starter can experience what is called "heat soak" due to the position of the solenoid near the exhaust manifold or headers. You can shield the solenoid with an aftermarket aluminum shield that fits/bolts over the solenoid to help keep heat off it.

Often heat soak can also be due to too small of a battery cable wire gauge size, especially when replacing with store bought cables which can be a smaller gauge than needed. You want a "2" gauge or "0" gauge cable.

Any form of corrosion will create additional resistance and the solenoid may not get the needed amps to crank the engine as well as it would when cold. The corrosion can build up inside the casing/wire even though it looks good on the outside. This includes the Purple wire that runs from the ignition switch to the "S" terminal lug on the solenoid.

Improper timing or even high factory compression ratios will make a starter labor when the engine is hot. It is not a starter problem, it is a timing/compression problem.

The Ford solenoid is a fix that some like to use and add to the starter system. I am a little ignorant on just how this works because you still have to run a battery cable to the GM starter solenoid which is what kicks in the starter gear that spins the engine.

I would not wire up a Ford solenoid. Just does not look clean and you have to run wires. And it is too easy to jump and steal your car.
The other alternative is to use a mini starter which allows you to rotate the solenoid away from the exhaust manifold - like the RobbMc mini. It also has more torque to crank the engine faster.

Here is a discussions in using the Ford solenoid.
The reason it's "safer" is because only the cable over to the solenoid is hot all the time, but the cable down to the starter is only hot when in crank in a "remote solenoid" setup. This also cures hot solenoid, no crank situations as obviously, the solenoid is wherever you put it.
Could not agree more that this is FORD folks. It has no business in a GTO.
Take care when you rounte your wires. Shield them as they should be. All will be well!
 
#22 ·
I know with a race car you have to have a power shut off switch. Why use the Ford solenoid in the trunk as opposed to running the 000 wire closer to the starter and then the Ford solenoid? I ask because I plan on mounting a rear battery in my '68 and run the 000 wire directly to the Robbmc mini starter solenoid - minus the Ford solenoid. And, this is not a race car.
 
#21 ·
I get why a hot rod might use the Ford solenoid so as to take advantage of the battery studs for things like the 1-wire alt. or hooking up power feeds.

I get that you are disconnecting the battery cable to the GM solenoid. I get that you are now attaching a battery cable from the Ford solenoid right back where you just took off the GM cable.

I get that you are removing the Purple "Start" wire to the "S" terminal post on the GM solenoid and are now running a jumper wire from the battery cable lug on the solenoid to the "S" terminal.

I get that you connect the battery cable from the positive battery terminal to one side of the Ford solenoid's battery lug, the other battery lug has the cable that runs to the GM starter solenoid lug along with the jumper S "Start" wire.

I get that there is no power going to the GM starter using the Ford solenoid as a 12V power cut off switch, and with the old GM set-up the battery/12V is constant to the solenoid.

I get it that the Purple "Start" wire that went to the GM "S" solenoid post now gets attached to the smaller "I" post on the Ford solenoid and when you turn the key to "Start" that this opens the flow of electricity between the battery post-to-solenoid lug and to the opposite solenoid lug-to-GM solenoid battery post. I get that by doing this change over in location of the Purple "S" from the GM solenoid to the remote Ford solenoid removes it from being near the heat of an exhaust manifold or header.

Here is what is listed on the MAD description, "The problem occurs because the large solenoid on the GM starter draws 40 to 50 amps at the moment the key is turned to "START." And that large amount of current must flow through a very lengthy circuit, from the battery to the dash area. Through dash wiring and switches, back out through the under-hood wiring, finally to the starter."

OK, the activation of either the GM solenoid or Ford solenoid is still being activated by the Purple "Start" wire, all I did was move it from the GM solenoid "S" lug to the Ford solenoid "I" "Start" lug. HOW DID I CHANGE/ELIMINATE the current flow through a very lengthy circuit from Ford solenoid lug to the dash area, through dash wiring and switches, back out through the under-hood wiring, and finally to the Ford solenoid "I" lug??????

Enclosed is a drawing that is my example for the above. I still have to connect the 12V power wire that was attached to the GM solenoid that brings power to my circuitry/fuse box. So the current flow HAS NOT changed going through the lengthy wiring circuit because it still has to in order for it to energize my ignition switch that sends power out along the Purple "Start" wire to activate the Ford solenoid through the "I" lug. So all I am doing is swapping my GM solenoid 12V power wire that supplies 12V to all my switches/gauges/accessories to the 12V battery lug on the Ford solenoid having the battery cable going from the battery post to the Ford solenoid lug - I will still have constant 12V going into my wiring circuitry, just not to the starter. AND, depending where I mount the Ford solenoid, I may have to extend/splice the 12V power wire/Purple "S" wire to reach the remote Ford solenoid.


MAD also says, " (2) SLOW CRANKING, a gr-r-runt, gr-r-runt. This kit (Ford solenoid) won't fix it! You'll need to work with ignition timing, battery cables, the starter, and the rest of the system."

Another website compares the GM set-up with the Ford change over and states, "This set-up DOES NOT make the GM solenoid any cooler. It just gives it a better current supply." Well, better current supply may also depend on battery condition, cable length & gauge size, good connections, good grounds, and any corrosion or frayed wiring that can lead to resistance.

I get why a hot rod might use the Ford solenoid so as to take advantage of the battery studs for things like the 1-wire alt. or hooking up power feeds.

I get that you are disconnecting the battery cable to the GM solenoid. I get that you are now attaching a battery cable from the Ford solenoid right back where you just took off the GM cable.

I get that you are removing the Purple "Start" wire to the S terminal on the solenoid and are now running a jumper wire from the battery cable lug on the solenoid to the S terminal.

I get that you connect the battery cable from the battery to one side of the Ford solenoid's battery lug, the other battery lug has the cable that runs to the GM starter solenoid lug with the jumper S "Start" wire.

I get that there is no power going to the GM starter using the Ford solenoid as a interpreter/cut off switch, and with the old GM set-up the battery/12V is constant to the solenoid.

I get it that the Purple "Start" wire that went to the GM solenoid now gets attached to one of the smaller lugs on the Ford solenoid to create the connection between the battery post -to-solenoid lug and solenoid lug-to-GM solenoid battery post, and that it is removed from being near an exhaust manifold or header.

Here is what is listed on the MAD description, "The problem occurs because the large solenoid on the GM starter draws 40 to 50 amps at the moment the key is turned to "START." And that large amount of current must flow through a very lengthy circuit, from the battery to the dash area. Through dash wiring and switches, back out through the under-hood wiring, finally to the starter."

OK, the activation of either the GM solenoid or Ford solenoid is still being activated by the Purple "Start" wire, all I did was move it from the GM solenoid "S" lug to the Ford solenoid "I" "Start" lug. HOW DID I CHANGE/ELIMINATE the current flow through a very lengthy circuit from Ford solenoid lug to the dash area, through dash wiring and switches, back out through the under-hood wiring, and finally to the Ford solenoid "I" lug??????

Enclosed is a drawing that is my example for the above. I still have to connect the 12V power wire that was attached to the GM solenoid that brings power to my circuitry/fuse box. So the current flow HAS NOT changed going through the lengthy wiring circuit because it still has to in order for it to energize my ignition switch that sends power out along the Purple "Start" wire to activate the Ford solenoid through the "I" lug. So all I am doing is swapping my 12V power wire that supplies 12V to all my switches/gauges/accessories to the 12V battery lug on the Ford solenoid having the battery cable going from the battery post to the Ford solenoid lug - I will still have constant 12V going into my wiring circuitry, just not to the starter. AND, depending where I mount the Ford solenoid, I may have to extend/splice the 12V power wire/Purple "S" wire to reach the Ford solenoid.


MAD also sayd, " (2) SLOW CRANKING, a gr-r-runt, gr-r-runt. This kit (Ford solenoid) won't fix it! You'll need to work with ignition timing, battery cables, the starter, and the rest of the system."

Another website compares the GM set-up with the Ford change over and states, "This set-up DOES NOT make the GM solenoid any cooler. It just gives it a better current supply."

Heat shields for the starter/solenoid, heat wrap, and heat blankets can help keep heat away.

Using a heavy gauge battery cable can improve the voltage supply to the starter.

From a other post, "One area that people forget is the "ground" path. If you are supplying 150A from the battery to the starter motor, then 150A has to go back from the starter motor to the battery. There are two current paths to deal with, not one. Remember that strap from the cylinder head to the firewall that you didn't bother to put back on because it was a pain? Put it on. Run the same sized cable from the starter to the chassis as you do from the battery to the solenoid, then make sure that the negative side connection from the battery to the chassis is excellent, nothing less."

From another forum with regards to needed amps to spin a 2HP GM starter, and I am going to guess this is with no load on it, ie spinning freely, "At 746 watts/hp, a 100% efficient 2 hp starter would draw about 125 amps at 12v. If the starter is only 75% efficient, it would take 166 amps to get the same 2 hp. If the applied voltage drops to 10 volts because of the load of our 75% efficient starter, it will now take 199 amps to make 2 hp."

A good starter will normally draw 60 to 150 amps with no load on it, and up to 250 amps under load (while cranking the engine). Amp needs can go even higher depending on your compression, timing, oil weight and outside temperature. And if brushes, armature, bushings are worn out in the starter itself, efficiency drops and more amps may be required

So my personal opinion is that I really don't see many advantages to use the Ford solenoid and I would not use one on my car. It may be more of a band-aid than a fix when the heat-soak problem may be cured with correct/larger gauge cables, heat shielding, good battery, or mini-starter with clockable solenoid. I can see an advantage to connecting a 1-wire alternator wire to the solenoid lug being a cleaner installation than most who hook it to the battery post. The positive cable lug on the Ford solenoid would be a good place to hook up any accessory wires such as electric fans, relays, or electrical add-ons. Eliminating constant power to the starter? To what gain?

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#23 ·
If I did it the way you described I would have a very long hot wire from the battery in the rear to the Ford solenoid up front. In the event the car crashed that would be more dangerous than having the very short hot wire with the solenoid in the rear. My Ford solenoid is mounted onto the battery box, so the hot wire is as short as possible. I had to implement for both safety and for NHRA.

Although I do have a one wire alternator, I don't have any power feeds tied into it. One down side of making it NHRA legal is that I can't tie the alternator wire directly to my switch controls. The reason is that when the master switch at the back of the car is turned off, the engine has to stop running. If the one wire on the alternator goes directly to power (even the switched OFF side) then it will self energize enough to keep the engine running. That's why they test you in tech by turning off the switch in the back with the engine running. If it doesn't shut off you are DQ'd. So I have a #8 wire going from the alternator to the non-battery side of the switch in the rear, then the same size wire going back up to the switch box and controls up front. But that wire comes off of the switched side of the "OFF" switch. What I didn't like about this was the voltage loss to my controls. The easy way would have been to run the alternator wire directly to the controls up front, which would have given me maximum voltage. But then the rear switch would not shut off the engine.

I also understand that the current going through the positive cable also has a return path to ground. My professional training is in electronic engineering, albeit it in computers. I have a 000 ground wire from the negative terminal of the battery to the frame in the rear of the car, and a 000 wire on each side of the engine to the frame. Technically this can cause ground current loops, but at the current we are talking about that is not a problem.

It's late, so I hope I didn't screw up any of my explanation.
 
#25 ·
No screw-ups! LOL I know a race car has to meet NHRA or IHRA tech per their guide book. Just was curious as to your set-up. I have heard of some guys state they run a second parallel positive cable up to the starter to provide better current flow from the trunk mounted battery. Not sure if there is an advantage to this or it was just because the owner used the lighter/smaller gauge wire versus just one single 000 gauge wire. Might have been an availability thing for him or cost.
 
#26 ·
Mine is a dedicated single wire to the starter, and my 000 is overkill. But a lot of times I like overkill. Mine is welding cable, so it is pretty flexible - considering. I don't see a good functional reason to put the battery in the trunk for a streetcar, unless it is for traction for racing or the desire to clean up the appearance under the hood.

If I did do it on my GTO I would still put the Ford solenoid in the rear by the battery. There's no downside to it.

I did forget about one other ground wire I have. I put two "power posts" about where the heater core would have been. This gave me a good attachment location for all power and ground requirements up front. The ground stud also has a 000 wire to the frame. Overall I've got about 20 pounds of 000 wire. I was bracket racing, so I didn't care if I had a little more weight.
 
#30 · (Edited)
These are a little disorganized, but just ask if there are any questions. I have no secrets. The first ones are a quick overview of the car. It's been sitting for some time, so it is quite dirty.

Note that I don't have any torsion bars on my trunk. I hold it up with a rod. You can see where I put the ON-OFF switch so anyone can access it to shut it down.

Motor vehicle Vehicle Car Steering wheel Center console
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#31 ·
OK, I finally finished dinner. These will show the battery box and some of the wiring. Note the battery is secured to the trunk floor. Actually there's welded tabs underneath so the battery hold down bolts tie directly into the frame. You can best see how the battery is secured in the picture that shows the Ford solenoid. Note that I got it and some other stuff from MAD Enterprises, but I don't know if he is still in business. There is a shallow metal tray with tabs that are held in by connecting to the through bolts. There is a plastic container that the battery fits into, and the whole assembly drops into the metal frame below. On top of that is an inverted U shaped frame that holds the battery in. On the top of that frame are two adjustable bolts that connect to the sides of the battery to hold it in place. On top of that is what looks like a seat belt. There are metal tabs on the end of it to tie into the through bolts. This belt holds the top of the battery case on.

On the Ford solenoid - there are two small wires. One for ground and the other for the start switch from the overhead switch panel. The one big wire goes directly to the starter. The other side of the relay is the 12 volts from the battery, and other 12 volt supply wires.

OOPS - it rotated the picture of the back of the switch. Reverse right and left in my description. Looking down the trunk you see the main On-Off switch. The left side is the switched side. The right side is the hot side. The red wire comes directly from the alternator. The other black wire on the hot side goes to the instrument panel. On the passenger side you will see two studs protruding. The left one is ground, with a 000 cable going to the frame. The right one is for 12 volts that I connected under the dash. This gave me access to voltage up front, and it's where I connect the timing light power cables. One caution here. The alternator wire is always hot. It is easy to forget that when the switch is off.

The ugly red and black cables are for the battery charger that I keep in the trunk. I should have taken it out before I took the pictures.


Electrical wiring Wire Electrical supply Technology Gas
Electrical wiring Wire Technology Electrical supply Electronic device
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Wire Electrical wiring Cable Technology Electronic device
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#36 ·
I'll toss in a couple of videos of the racecar. This one did not have the intended result, but it does show a complete run from pulling out of the staging lanes to getting back to my pit. This was at the Barona eighth mile track. It is on the Indian reservation in San Diego County. Every now and then the left lane goes squirrelly, and just one time. This was one of those runs. It started dancing around at the end of first, and it went totally out of shape when I shifted to second. It was much worse than it appears in the video. The ugly guy sticking his head in at the end is Robert Johnson. He is/was the driver for Jim Wangers' Ponte-Carlo. The white trailer on my left was D-Mac's (Dennis MacDonald).

 
#38 ·
gconsult—hope you’re rolling down the road by now!
1) All Pontiac V8’s have the starter in the same place! If it works for a 455, it’ll work on a 400–never mind what the parts store computer says!
2) Bigger is better. Molded terminals are better than clamp-on terminals.
3) Cars with HO/RA manifolds or headers can/should route the cable along the frame rail. Factory used a bracket that mounts to the motor mount (at least in 67).
4) MAD Electric Start-em-up kit (Ford solenoid) does two things:
A) The big wire to the starter in not “ hot” except while cranking. With factory setup, this cable is always “hot”, and if it gets pinched or burned it becomes an un-fused dead short to ground—definite fire hazard!
B) GM starters can have hot start problems, when the starter-mounted solenoid doesn’t work. This is partly because the solenoid requires more “juice” when hot, and partly due to voltage drop through the fuse block and ignition switch (the S terminal doesn’t get a full 12v). The Ford solenoid powers up the battery cable to the starter, which is jumpered to the S terminal on the starter, so the GM solenoid gets full voltage. If your solenoid is working (starter is cranking), then you don’t need this fix.
 
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