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Good Ground DOH!


v80z

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After fooling with the fuel last time and after the garage had aired out some I realized the benefits of a good ground to the engine. I am wiring now. I had continuity from the neg bat terminal to the engine and thought that the mounts were good enough grounds.

 

Anyway I have been bumping the motor with the starter to get #1 at TDC for Dizzy install. It has been rolling with alot of effort. I am using a battery charger in conjunction with the battery for starting. Thought the battery maybe weak. After a thorough charge the motor still turns slowly with the starter motor. I was rolling it for the dizzy install. I hit the starter and a spark jump from the driver's side engine compartment. I quickly shut things down. I inspected that side and did not see any wires in the vicinity. As I was probing I found the dipstick welded to the brake line!!!!

 

HMMMM Ya think this engine needs a better ground to the chassis?

 

 

Well got an old battery cable and grounded from the head to the body. Engine turns much faster now under the starter's power.

 

This whole hybrid path is a good learning experience.

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Yeah, I was moving my battery to the back, and thought I had bolted the ground to a good enough spot. Well after about a week of after work troubleshooting I found out it was the new ground cable, but also the old ground cable went at the same time, so when I moved it back, I had the symptoms. Well, we live, we learn.

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Just my opinion but...

 

If you put the battery in the back of the car, don't depend on the chassis to run your ground side of the circuits. Steel isn't a good enough conductor for that length. Run a separate ground cable from the battery to the engine block near the starter, and then run your body to engine ground from that area. Welding cable comes in black and it's cheap.

 

I run a tiny regular battery (can't remember the size, but it's for a small car) and 2-gage battery cables for positive and ground. Never really had a problem with starting.

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Thanks Pete. Thaht is an awesome idea for grounding. Zero resistance. I moved my battery to the back and grounded it on the rear bumper shock bolt holes with 1/0 cable. Brought the positive forward through a switch to the starter. But what you are saying is bring the ground forward as well and attach it to the block? Right?

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Thanks Pete. Thaht is an awesome idea for grounding. Zero resistance. I moved my battery to the back and grounded it on the rear bumper shock bolt holes with 1/0 cable. Brought the positive forward through a switch to the starter. But what you are saying is bring the ground forward as well and attach it to the block? Right?

Yes, use a second cable from the ground post to the engine block near the starter. 2 gage is probably fine, but 1 gage or 0 gage would be good insurance.

 

This will help the battery get a full charge also. Many times people forget that the ground side of the circuit is just as important as the positive side. Having a minimal voltage drop in both the positve charging wire from the alternator to the battery is important (and the positive sensing wire if you're using a 3-wire alternator, which is recommended for relocated battery systems), and on the ground side of the circuit will allow the alternator to apply the full charging voltage to the relocated battery. I use a ford start type "solenoid" (contactor, really), like this, to run my battery positive to, and I run a #8 wire from my alternator output to there. That means minimal voltage drop on the positive side of the charge circuit. I also run an 8 gage wire from the bottom alternator attachment lug (with the long bolt) to the place I run the 2 gage ground cable to on the engine block. This is probably one reason I always have a fully charged battery.

 

Of course, the same goes for the starter circuit - along with that nice big 1/0 gage battery positive cable from the battery to the starter, you need a nice big copper conductor for the negative side. That negative battery cable from the battery all the way to the engine block near the starter provides that low resistance path. Try seeing what the voltage is from the negative battery terminal on the battery to the starter mounting bolt while cranking the engine with the ignition unhooked. You might find that you're losing something near a volt due to reliance on the vehicle chassis (steel) to conduct that high starter current on the ground side of the circuit.

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