OK, so I've been driving this car for a while(over 1000 miles on it), ironing out the bugs for the summer before I get it painted in the fall. I thought I'd describe my electrical system and grounding to see if the car is properly grounded to some of the strict HAMB standards. Here's what it's got and I've done: -1935 Ford 5W with a sbc(fairly stock) and TH350 -12v Painless 8 circuit hot rod wiring harness -HEI distributor, alternator, and high-torque ministarter(153 tooth flexplate) -taillights, headlights, gauge bulbs, and hi/lo switch wired in The battery is in the trunk. My positive cable is 3/8" OD(not sure of the gauge, 4 maybe?) and obviously runs to the starter. I have a black, 3/8" negative cable going from the battery to the frame underneath the battery in the rear of the car. I also have a 1 1/4" negative grounding strap going from a header bolt closest to the starter, to the frame and a ground(3/8") from the trans./engine bolt to the frame. The connections are clean and free of paint. The headlights and gauge lights are ground to a shared drilled point on the frame. Are my battery cables too small for a battery-in-the-rear setup? My starter sometimes labors a little bit. Never have any charging issues, car runs cool, and all the lights are always bright and consistent. Well, what do ya think? Any comments or opinions are welcomed. Thanks a bunch... Adam
That sounds good to me, I would run a 2 gauge positive cable, ground strap from the body to the engine, the body to the frame. Other wise your system is good.
bigger is better, but not always needed. do the cables get hot from cranking over. in rear mounted batteries i like to go with a min of 2 gauge, some need 0.
Bigger starter cable is also better to make up for the length that it has to travel to the front of the vehicle.
at least 1 but 2 should be ok from the + post of the battery to the starter. then 1 or 2 from the - side of the battery all the way to the engine block. Then a ground strap from that same place on the block to the frame. Then a ground strap from the same place on the block again to the body that's how i do it , never any problems or starting issues you may think it's overkill , but i feel it makes a difference
Go to your local tractor supply and tell them you want cables made out of 0 or 00 and your starter will never labor again.....that is a healthy voltage drop going from the trunk to the engine.
I gotta agree. Run that ground cable all the way from the battery up the frame rail to the engine especially if your's is an older original frame. Make it easy for the current to pass without fighting it's way through any surface rust or 75yr old metal.
Battery In The Trunk? 1. Buy a 1100 cold cranking amp battery from Caterpillar. Cat makes the best batteries. Expensive but still the best in my humble opinion. 2. O or zero size battery cables with factor crimped ends. Any large truck shop can sell you the cable and crimp the ends I.E. Freightliner or Peterbilt dealship. 3. Used that O cable from the battery hot side to the starter solenoid. 4. Run ground wire from battery ground to car frame. remove all paint and rust from the frame. Bolt the end to the frame good and tight. Smear a little bearing grease around this connection. 4. Got to the front and run a ground cable (o size) from somewhere on the engine block to the frame. There are usually some extra threaded holes under the spark plugs on the side of the block and above the pan rail. Remove the paint and rust from the block and the frame. Bolt both ends up tight and again smear a little bearing grease on both ends. I have two cars, a 1939 Ford Coupe and a 1940 Willys Coupe and they both have the battery in the trunk. The both run and start, hot or cold. Hope this helps! 1940 Willys Coupe
Yes O or OO. Run both right to the engine. Positive to starter and negative to the block. I would also run a #12 or #14 from the negative side of battery to all other important areas of the car. Trunk area should have a bolt for needed grounds. Same thing inside the car. Under the dash. Up front for lighting etc. I've read so many posts where the same issue is the trouble. Lights, gauges, horns are never grounded correctly. Of course once they are all troubles go away. Both of my 50s Chevys have been done this way. One with a new harness and one done by following the shop manual wiring diagrams. I've never had an issue. I'm also an electrician with 38 years wiring things. Dom
Absolutely what he (and a few others) says! I've been building and wiring cars for 35+ years including many dragsters, hot rods and even the occasional... (forgive me, y'all)... street rod. Current passes through copper with ease, it has to fight it's way through an old car frame, a transmission case, etc. Just look at a copper strand through a microscope and then look at a piece of cold rolled steel, or worse yet, anything cast, and you'll see the difference. The single most common problem I find when I go behind someone else's work is related to the ground. Be sure it's sufficent, be sure to run the ground from the battery all the way to the engine block and you'll have no problems!
My 2 cents: bigger is better for batt cables More is better for grounds to the block I like using a ford starter relay I like junction blocks for grounds. More trouble in the short run, better in the long run
you stated grounding on a header bolt? I would go to the back of the head its self. Headers have that habit of loosening some times and going off the back of the head might look a little cleaner.
Well, there ya have it. Plenty of good info and suggestions. Looks like I'll run a 0 gauge + from the battery to the starter and a 0 gauge - from the battery to a spare bolt hole in the block(back of the head). I'll also run separate grounds from the body and frame to that same grounding bolt on the head. Basically what everyone recommended and exactly what 36 3-window said. Seems like a nice, clean, effective plan. Thanks, HAMB!
Just a quickie, besides exposing bare metal for a good ground connection....star washers that actually dig into the metal when the fastner is tightened are a good idea.
I's a crap shoot. You will hear from guys that have run the ground to the frame with no ill affects for years. My battery was under the seat of a P/U. It seemed to work great until I drove 2 hrs to rod run and it would not turn over at the registration desk. Embarrassing! Like most guys I assumed it was heat soak on the starter. I had a welding supply shop make my cables so I knew it wasn't a cable problem. I chased this problem for over a year. Someone told me to move the ground from the welded stud on the frame to a bolt in the trans case. I did it reluctantly thinking that they were crazy because it started just fine in the mornings.... It never happened again. Since then, I always run O ga cables and run the ground directly to the block or to the trans bolts. Your cables most likely will not be able to carry the extra amperage required to start a hot engine in hot weather. That is the most taxing event for your electrical system. Some guys will tell you to run jumper grounds from the frame to the block but to me every mechanical break in the starting circuit is a potential spot for corrosion and a loose connection. Welding cable and running the ground all the way to the tail shaft housing may seem like over kill unless you have gone through my experience. You may have no problems. Do ya feel lucky?
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