After the cranking problems that I had last sunday at Mopar Thunder, I've decided to do what should have been done long ago-rewire this car to todays standards.
First, a little back ground. '72 E body barracuda, batteries (2 red top optimas) in the trunk, no alt. 440 +.030", 13.6:1 compression, race gas. The pos cable went from each battery to master disconnect, to the starter. from the starter to the starter relay, to the rest of the car via factory fusible link, using factory ign switch. Ground from each battery went to frame rails under the battery.
Never had a problem with this set up except a battery went bad last year, (replaced under battery warranty) even running 2 classes at Bristol (going to finals in both) with a total of 17 passes in 10 hours, charging in between early rounds.
Then changes were made. Gear drive, crank trigger, locked out timing at 36*, MSD pro power coil. Had run this set up for 4 races with a total of 28 passes until last weekend (mopar thunder). Fri we made 5 passes, charging between rounds. Sat ran 2 classes, 13 passes no problems. Sunday, take car out of the trailer (charged batteries over nite) low voltage caused starter kick back. Nothing but trouble from that point forward. 6 passes, had to be jump started 3 of them.
The questions; I'm pulling pos and neg cables from batteries to starter, with grounds also to frame. Will a #2 gauge cable be large enough?
Will putting ignition switch seperate from start switch be ok with out a start retard? (start spinning engine, then light the fire). I'm also going to remove factory starter switch, will 14 gauge wire be large enough for every thing else? (except relay to starter, 10 gauge)
Am I missing anything else? I will appriceate any guidance you guys can give me.
Sorry this turned out so long, but this HAS to get fixed. Thanks again, Brian Dunnigan

#2 cable is fine, but it's time for an alternator imo. your life would be much easier. and you could run 1 battery.

I agree you lose the starter retard.One thing to add. make sure you run a ground cable from the battery to the motor.
In my cars I run a ground cable from the battery forward to a stud in the roll cage usually at the A bar near the dash. From there to both heads. Yes both . An old timer said it's the added short point for insuring a good ground for the plugs. from the dash stud ground is also where I run my MSD ground.

My battery is in the front and I run 1 gauge cables.My 12.5 440 cranks like a /6 with the mini starter.Rocky

I would also check the master disconnect switch. I was running 2 batteries through what I thought was a good moroso switch. After switching out batteries several times, I pulled the switch to find out it only had a 60 amp rating. Replaced it with a 300 amp switch and the motor cranks over no problem, even when hot with 15 to 1 comp.

I run 1 battery... 1 ground.. it goes to a stud welded
to the chassis same at the front... I run a alt...
I did have a field wire fall off the alt last weekend
and due to that it was the FIRST time in 6 years I
have ever had a charger on my car and that includes
the winter months... from what some are saying maybe
I should run maybe 10 grounds... come on guys... 1 GOOD
ground is all you need... keep them clean and a big
enough wire size... electricity still works the same
as it always has... it goes to the least resistance

Thanks for the replys guys. Thats what I was looking for, comments and sugustions from real world experience, "been there and done that" racers.
The one thing that I never concidered was the master disconnect. I've seen them fail completely, but not partly. I will check that when I get the rewiring completed.
I am replaceing the hot cable with 2 ga, ground from battery to engine block will be 1 ga.
Anyone else have sugustions?
Thanks again,
Brian Dunnigan

As Quicktree mentioned,get a good alternator. I ran my car for a few years without one and now have one,best thing I did to the car.

i can't for the life of me understand why people insist on running race cars without a charging system. comp or prostock is one thing but for the vast majority of us a charging system is a no-brainer...use one. as for grounds i know many disagree and that's fine but imho there's plenty of steel to have an acceptable voltage drop. i never run a ground from the battery to the engine, you do of course need to use good judgment on the connections and such. it's also worth noting that most if not all single wire alternators are somewhat crippled by the fact that the voltage regulator only sees the output voltage as opposed to the actual voltage found throughout the system which is going to be lower. the best charging system should have a voltage sense wire connected well downstream of the alternator output.

Go to welding shop and get small welding cable and run from disconnect switch to starter. The multi-fine strand wire has the least reistance and delivers the most power to the starter. Connect it to the batteries positive terminals at the disconnect switch in the rear. Ground each battery with short cables to back of car. Take another ground wire,attatch it to each of the battery grounds in back, and attatch it to the motor. Put the ground for the msd to this ground at the motor. This system gives the starter the power it needs and the msd the best ground.

resistance is all about cross-sectional area of the cable

X2 - flexible is a convenience, nothing to do with how much current it transmits.

Steel (chassis) is an acceptable ground, provided that the X-sectional area is larger than the cable you're not using, and that all connectors have a contact surface at least as large. A 5/16-18 bolt into the firewall isn't enough.

but... why would anyone use smaller than 00 cable for a long run?

Be wary of buying cable at a flea market, or out of the trunk of a car - it may still belong to the utility company.

resistance is all about cross-sectional area of the cable

Sort of correct but stranded cable has more surface area for the electrons to flow on - so it has benefits of being lighter, flexible and stronger and it will carry the same amp rating as solid piece of wire of the same gauge and material - that applies to pretty much to low voltage dc and ac circuits.

There are some new copper clad aluminum cables that are much lighter than copper for main feeds - I am not sure how well they perform in the long term as usually aluminum and copper together eventually corrode and get brittle

Let me throw my in here about size and application on wire sizes in D.C circuits, to little of a wire will increase the resistance during large current requirements (starting the motor), it forces more current through the smaller cable causing heat in the wires which increases the resistance To large of a cable size is not usually a problem in cars, especially race cars Proper grounding is As already said use two grounds in the back and the same size cable (# 1,0 or 00, not #4 or #2 ) as the hot feed for the ground to the front and attach it to the motor with a large wire size eyelet, I use a 7/16 eyelet soddiered(SP?) onto my cables and attach them to the 7/16 transmission bolts to the block for the ground and directly to the starter lug on the starter for the main feed from the batterys. I use a #2 cable for the main feed to the rest of the circuits on the car from the starter One of the things I have learned on low voltage circuits is to use the largest wire size needed to avoid any voltage drop at the far end being tested You will always see a voltage drop at the starter motor when it is spinning the motor over, you shouldn't see any voltage drop at the starter when it is not being used (or anything else drawing curent)versus checking the voltage at the batteries BTW, on digital VOM meters don't worry about a change of .01 volt differences, do worry if it is more than that there shuold be very minimal voltage drop, less than .01 volts, through the main battery feed to the front