Engine Ground

[olddog]

I was under the hood looking at a few things and it dawned on me that I couldn't find a heavy ground wire on the engine. Typically the battery ground cable is on the engine. My battery is in the trunk. The ground for the battery is going to the frame back there.

There is a light (#14 wire) on the intake. It must be getting a ground through the motor mounts (rubber?) or the braded hoses. It has braded hoses for power stearing, a remote oil filter, and the fuel lines (EFI return system). The idea of the fuel lines carrying the 500 amp draw by the starter leaves me a little unsettled in the stomach.

What is the best solution? A sort heavy wire from engine to frame, or run it all the way back to the battery?

Any stranded exterior grade wire OK, or some special wire needed? I guessing about 00 coper wire?

[xlr8or]

Use a battery cable with flat spade ends and attach from the block or bellhousing bolt to the frame and you should be fine.

[Rick Parker]

It mat have a cable grounding at the transmission. OTHERWISE you may be pulling all the starter current through a collection of undersized grounds that you described (not good).

[FUNFER2]

I would buy a trunk battery kit from Summit, Jegs ect. It comes with every thing you need. Make sure to clean of the paint or rusted area when mounting a ground. I use welders spray paint on the surface so it won't rust or on aluminum so it won't oxidize.

[trularin]

Put a #8 or better wire strap between the frame and the engine. Use soldered eyelets and shrink wrap the bond. Use a star washer under the bolts.

Just my opinion.

[Blas]

You can easily add a ground cable from a bolt on your starter to a good chassis ground. I agree with cleaning the paint and using a star washer to insure a good connection. As for wire size, check the cable size on your positive lead (red) on the battery and go maybe one or two cable sizes smaller because the run is so short. Use a black cable too not red. I would guess you have a ground on the trans somewhere. Worst case would be grounding thru the cooling system..A local forklift battery shop can usually make a great cable too. Try a welding shop, welding cable is nice and flexable. Determine a length and the orientation of the hoops before you purchase. You can't twist a heavy short cable too much when installing. Provide slack or a loop to allow for engine movement too...

[WarrenG]

You can also use a braided wire ground strap between the engine and the frame. I've seen them used in cars and we use them all the time in heavy equipment applications.

[olddog]

Thanks to all.

[Michael C Henry]

You can't have too much ground. A fiberglass car has to use the frame for a conductor. Steel isn't as goond a conductor as copper. To make sure that everything is operating alternater to engine 8-4 gauge engine to battery negative as large a cable as starter positive cable. Things like the dash and wiper motor, ignition boxes,lights and such can all be connected by ground wires running to comon points like a bolt with several wires stacked on a bolt here or there. I have a 70 amp alternater and it hardly ever goes full tilt but I think I could handle it. You want cable large enough to not get hot when being used. The haveiest current draw will be when starting. Useing my car as example electric fuel pumps, ignition, will, allways be on. Fans and lights may or maynot be turned on. I remember reading about the Chevey guys with the high power ignition not having enough ground and the ignition current finds it's way back to battery by way of accelerater cable causing it to weld it's self in place. Another cable for ground from frontelectric componets to battery ground is good insurance for reliablity.

[Double Venom]

Old Dog,

I'm not a serious electrical guy by any means, but we got into the technicalities of a "ground" on these fiberglass cars in a big way. With the battery grounded to the frame, especially a rear mounted batttery grounded in the rear is not the way to go-at all. The above post really does have some good points! Especially for cars running an EFI system with injectors etc.

A 00 cable should be run from the battery ALL the way to the engine, then a grounding strap run from the engine/transmission to the frame.

What you have could result in gauges being burned out, not working properly, dim headlights, turn signals working slow or dimly, ignition system problems, and eventually starter problems among many other minor nuances.

Just what we learned here on the forum.

DV

[olddog]

Thought I should update this.

A friend had an old arc welder cable that he gave me. I stripped an end and the copper was in perfect shape. I cut to fit and I soldered new ends on it. Shrink wrapped the ends. I attached it to the battery cable where it bolted to the frame, and the ran it up to the bell housing bolt near the starter.

For the record when I got under the car it did have a 1" flat wire going from the engine to frame at the motor mount of the drivers side. I didn't like the idea of that much current flowing through the frame for that distance, so I went ahead an added the heavy copper cable. I didn't want to miss represent that there was no ground, as that could reflect on the previous owner. My mistake.

Prior to the heavy copper ground I installed the voltage meter would pull down to 9 volts with the starter turning and engine hot. Now it only pulls down to a little over 10 volts at the same conditions, so the better ground did help a little.

Thanks for all the tips.

[Argess]

Glad you have the situation rectified. Lots of good advice from what I see. But I thought I'd like to add, why not move the battery to the engine compartment? Why?

1/ Only need a couple of short #4 cables

2/ no acid or acid fume corrosion of anything metal in the trunk, like the "floor"

3/ Lead-Acid batteries in a confined space? Explosive hydrogen gas may fill the trunk.

4/ Maybe a little easier to get organized when using jumper cables. At least no sparks near, or on, the gas filler tube to the tank in the event of an accidental bump.

5/ AND, if you have enough Hp, it can help keep the front down.....LOL.

But lots do it with no problems....just a thought

ps: one disadvantage to front mounting...at least in my case....I have to remove the right valve cover to change the battery

[767Jockey]

I'm wiring my car now with a Ron Francis wiring harness. They are adamant in their directions as well as in their catalog that the frame should not be used for a ground. They strongly and repeatedly emphasize that a heavy ground cable should be run from the negative terminal of the battery directly up to the starter mounting bolt on the engine. From there you run a ground from the starter bolt to the frame, and start grounding the other items in the car accordingly.

[olddog]

Argess
I never considered changing the location. You make some good points. I will say, it came in handy this evening, as I left the lights on today at work, and it made jumping it much easier. That reminds me, I better go out and open the trunk after charging a dead battery in it. Thanks

767Jockey
Most of my experiance has been in industry not cars. When you have dissimilar metals connected and pass large quantities of current through them bad things can happen. In my cars case, I had copper electrons, cast iron electrons, and steel electrons all flowing through each other. It can lead to corrosion, and change metals in other ways. Sometimes it causes cracking and other strange things. On top of that steel is not a good conductor of electricity like copper is.

[Argess]

I had to jump mine nnce (with battery in the front and positive terminal under the fender). Hooked the negative wire to battery and positive cable to starting solenoid on firewall. Nothing to it.

Steel may not be as good a conductor, but with the frame, you have massive amounts there. I suspect the extra connections of using the frame to be the sore spot. At any rate, your extra copper cable seemed to make a significant difference, and really, in the end, as long as you get the results you want, whatever you do is OK.....er.....legal things I mean.....LOL

[Blas]

Jumping your car by connecting to the hot side of the starter solenoid on the firewall with the “+” cable works great, but take note of the clearance between a metal firewall and the solenoid terminal it’s usually quite small for the jumper cable clamp. Touching that metal firewall creates a “BIG” electrical short not to mentiona a nasty burn-mark in the firewall. And you’ll most likely be on the other side of the car turning the key when the clamp moves…
The “-“ cable can be connected anywhere on the chassis, and should be connected last. Connecting both cables to battery terminals can cause a spark and the off-gas (hydrogen) from a battery is quite explosive…Proper grounding also prevents the engine from grounding thru the cooling system (i.e. the radiator) which causes all kinds of other problems.

[Buzz]

This thread is very timely. I have been experiencing nagging ignition and starter issues lately and I suspected a grounding problem. I was planning to check all ground connections, but now, after reading some of the posts I will beef up the entire system.