My Bronco is not my daily driver. I do not drive it to work (I do sometimes..just not regularly). My favorite time to drive it is when I'm off. Many times when I'm working nights, I love to wake up and get in it and me and my wife will go mess around.
PROBLEM: the whole time I had it, if it had not run for a couple days, you had to go out and pump the gas, try to start it, and go back in for a few minutes, come back outside and it would usually crank up and be good to go.
Now this was not an ideal scenario, but something I accepted as quirkyness and a one barrel carb having to feed mile long intake runners.....stone cold....Nevertheless it bugged me because when I ran nothing but small block chevies I had those where holy crap all you had to do was bump the starter and they would light off and be running......why couldnt my bronco be like that!?!?!?!?!?!?!?!?

Recently, it would not want to start AT ALL without and act of congress... It almost acted like it was getting NO spark but I checked and it was getting a measly very light yellow whimpering spark....
So I would keep cranking, let it rest, pump the acc pump, decide to not pump it, finally get it running....THEN once it was warm it still was difficult but would always go.

SO....I finally got real fed up with this. I always have spare ignition modules (or whatever those silver boxes that mount on the fender well by the master cyl). So, I plugged a different one in. This was about a 50% improvement. I had a year old distributor in it so I thought I would check timing. Went out with a white paint pen, marked the balancer where the notch was, unplugged the vacuum advance, started the truck BAM perfect 8-10 BFTDC......I had eyeballed the install, when I install new distributors, I put them in based on the marks I made, then check the hot restarts, if it drags, I back it down a little.
Meanwhile I noticed the pos cable from the battery to the solenoid would get REALLY HOT while cranking. I also had those conversion battery cable terminals that have little 3/8 or 7/16 bolts and clamp the strap down....so I decided to get new cables. I took that little clip off the frame for the ground cable and was going to get a really long ground cable and strip the insulation off for the frame clamp then continue on...but I couldn't find one long enough. So I bought two ground straps, one to connect to the battery and one for the frame clip to the top bolt of the starter. Previously I had the ground going to the alternator bracket. I also bought a new pos cable. all the cables I bought were nice and new and SEALED ENDS!!!!!!!!!!!!!!!!!!!!!!!!


the first time I bumped the starter I almost jumped out of the truck in fear I can not describe how fast the motor cranked and started. So, I thought okay you got lucky try it again when its colder then He$$ outside and its been sitting all night!!! Same result! STARTS RIGHT UP BAM!

thats my story, hope it helps. I had a similar experience on a yamaha outboard I changed battery cables, you could see where the green and black was infiltrating those twined insides, and similar as well because I had cut those terminals off and put those crap adapters on to go from top terminal to side terminals or vice versa or back and forth

 

Those battery term ends with clamp and two bolts are really to be considered, emergency, cable ends. They may work well for some time, even if you put some kind of sealant over them. Eventually moisture finds it way in and corrosion you can't see starts to form. Open top batteries (you add the water now and then) E-mit gases when the battery is charging and some that don't have greatly sealed posts, send the gases up around the + an - posts, causing the pretty colored acid blooms that grow around the terms/posts. This all leads to more and more resistance over time and eventually problems such as you experienced.

New replacement cables are the way to go. If you could get cables a gauge or two heavier than stock would be even better. I've had the opportunity to make my own many times and I use welding cable, crimp on ends, HD battery cable heat shrink with built in sealant.

 

I call it the "$20 dollar tune-up", you can try to explain it to people but they don't want to believe it for some reason, so it's damn difficult to get people to replace them even after 20, 40 or even 50+ years. Almost a nearly invisible layer of corrosion at connections and ground points is enough to prevent good transfer in the starting or charging system, headlights, ignition, etc.

Sometimes you'll hear people suggesting to "measure the ohms resistance" of a cable or connection. This won't work, for several reasons, but probably the most important is the fact that in a high current circuit only a few hundredths of a single ohm is enough resistance to become completely defective. High current carrying connections, therefore, are always tested under load, in parallel, for voltage drop. Typically just a few tenths of a volt is the limit. Both starting and charging circuits need the very least possible resistance to properly function. It pays dividends to stay on top of this.

 

Check these guys out. A little more than you pay for off-the-shelf at the parts house but beefier and custom fit.

Battery cables for F150, Bronco, Mustang and other Ford applications

 

Here's a handy test from the above linked battery cable vendor. It's quick and easy, no disassembly required. You might be surprised how much current is being robbed or lost in the paint or corrosion. The voltage drop has a similar bad effect on the alternator too, meaning batteries that won't get charged.

Testing:

The rule of thumb is there should be less than 0.5V* voltage drop, round-trip from the positive battery post to negative battery post during cranking. This can be measured with a voltmeter. Put one lead on the positive battery post and the other on the starter stud. Have an assistant crank the engine and record the voltage while the engine is cranking. Do the same thing for the negative side. Put one lead on the starter case and the other on the negative post of the battery and measure the voltage with the engine cranking. Add the two numbers together and the sum should be less than 0.5 V.

* Voltage "drop" is measured as a POSITIVE number. It represents the voltage being LOST in the circuit. By placing a voltmeter in parallel across a cable or connection under load we can measure the total drop. Some people have the mistaken impression that "voltage drop" testing is simply checking for 12.6 volts at the component.

 

A lot of times I have replaced old battery cables with oversize welding cable (not because that is better than battery cable, but because I have lots of it). Instead of using the end clamps that clamp directly to the cable, I first affix copper terminals to the cable. I have a homemade fixture that holds the bottom half of the copper terminal while I stake the top of the terminal to the cable with a dull cold chisel and a big hammer. Good contact all around the cable, and easy to seal the little bit of exposed wire with silicone sealant. Then I use the kind of battery clamp that has a stud to attach the cable.

If you have a flaring tool (for brake lines and such), you can use the clamp part of it as your fixture to hold the bottom of the copper terminal while staking it with the cold chisel. Just put half of the flaring tool clamp in your bench vise, and set the copper terminal into the half-hole that fits.

It always amazes me how often battery clamps and cables that LOOK okay and clean enough can be made to work a lot better after you unclamp them and have a go at the clamps and terminals with the special wire-brush gizmo. It's also amazing how often some guys let the electrolyte level in their batteries get WAY low.

 

S S, A good way for some one to make their own cable(s) and I have done what you describe.

Like to add a bit more on the subject for those who might make a custom cable. You can usually get components, cable, lugs in various cable gauges and hole diameters and heat shrink, from a HD truck parts store. They may even offer P and N post clamp ends, tho they may be a bit harder to stake with a dull cold chisel. If a person has a friend who is an electrician or electrical contractor, they most all have a HD crimping tools for attaching lugs to cable. It looks like a BIG bolt cutter with jaws that have adjustable V's to match the lug size you would crimp.

Those who are purist and need to have the batteries and cable look OEM'ed wont do this but, this subject has to do with cranking the engine over so good, you think it will jump out of its mounts. This is from 30 yrs of maintaining a private fleet. When needing a new battery we converted every truck and fork lift to a TOP STUD group 31 HIGH CYCLE batteries. They will fit in 65-66 slicks with battery box up front next to Rad. Don't know about fitting slicks with under floor or firewall mounted boxes. No more post and P/N cable ends to deal with. The lug goes on the stud and secured with a nut. No more battery maintenance EVER and battery life of 6 to 8 years.

 

"Slicks"??

I like your no-clamp studs, with wingnuts, IF you put a little grease or anti-seize on the studs . . . which "my guys" don't on their trucks and equipment, so the wingnuts rust to the studs and you still to reef at the wingnuts with a big persuader.

Nobody ever has time to apply anti-seize, but they always have to find time to pry and twist and chisel stuff apart. Battery clamps, tailpipe clamps, never ever any anti-seize . . . ..

 

Don't forget brake bleed screws

 

I was going to say that and then figured, "oh well, nobody but me would do that." YEAH, the factory saves a quarter of a cent per nipple by buying the smallest ones and of course they never install anything with anti-seize. So even your best fitting wrench rounds off the tiny hex and you end up using a vise-grip pliers and tapping it with a hammer. When you finally get the nipple freed-up, you find that as usual it is so short that your bleeder-hose keeps getting knocked off. I HATE THIS!!! Whenever I can, I get bigger, longer nipples (with the same thread) from a local truck supply. And put 'em in with anti-seize!!

 

"Slicks"?? LOL, sorry about that, I only visit the 61-66 (Slicks) and Inline Six Forums. Not thinking sometimes where I'm at. You'll understand when you get a little older. Thanks for waking me up.

Never Seize, we seem to be on the same page, I even Never Seize the joints of an exhaust system, seems a little ****, which I am at times.

Back to subject at hand. On the top stud batteries I use(d) stainless nuts and washers. Way back when we went to High Cycle Batteries, we used Delco 1100 series. At a seminar, talking with a Delco rep about the 1100 series, he said our top studs and top posts are triple sealed to prevent gases from escaping. If I had a battery that developed acid bloom there, they would warranty the batt as a failure. Never had an acid bloom with them. At scheduled PMs, we would remove battery box cover(if there was one)look at the batts, do a loaded charging voltage test and put the cover back on. We did use a spray terminal protectant that was like a black lacquer paint called Corro Gard.

 

When I get a little older? I'm almost 70 now, can't wait forever. So a "slick" is a '61-'67 Econoline? I've heard them called "Bull-nose" and "Gen 1," never "slicks."

 

Slicks are 61 to 66 F-100 and larger F- series. Here on FTE they are known as the "Slick Sixties". Take a look for the fun of it. In F-100-350 trucks we deal with 2 different inline 6 engine families and 2 V-8 engine families. We have everything from better than showroom restorations to the most radical mods you can think of.

Oh, and I'm 73 going on....