What is the best spot to ground a 1972 centurion 455 motor

[Guest ballafromtexas2]

When its on the battery charger it has no problem spinning over. When its not on the charger the ground wire gets hot and it barely wants to spin over. It has an hei , i dont know if that makes a difference. Right now i have it grounded on the motor where the a/c bracket connects and the little thin ground to the chassis. It has a fresh 1000 cranking amp battery on it. Any help would be greatly appreciated . Also does anyone have the diagram setup for the starter with a hei swap.

[old-tank]

If only that cable gets hot, the cable is undersized or defective from internal corrosion. Heavily painted brackets mounted to heavily painted engines are not a good ground source. Ground to a starter mounting bolt as a test.

[Guest brh]

Make sure the ground is your problem. Just an FYI I had one of these and it loved to eat starters every 6 months. Is it possible the charger just gives the starter extra amps it needs because its gonna go, and is pulling way too much amperage?? Just thinking out loud.

[Ben Bruce aka First Born]

Willy is spot on. One can not have too large a ground nor too many grounds.

Story in point. In 1987 I bought a 1985 Autocar [i know, it is a truck, not a Buick]. Over the next couple of years, the headlight and clearance light switches, which were toggle switches, needed replacing frequently. One day, fooling around under the hood, I grabbed the ground wire from the engine to the cab. Burned my hand!! I went directly to a shop and had a ground cable made up with OO gauge[overkill, I suppose] cable. I drove that truck for another eleven years and never replaced another toggle switch.

Ben

[JohnD1956]

I agree that the ground is problematic. I would move it off the A/C bracket which is probably aluminum and look for another spot directly on the cast iron motor block.

That being said though, It's tough to think that a 1K Amp battery need help from a charger to spin the car over easily. I'm thinking the battery is defective.

[Guest ballafromtexas2]

Ok ground wire is new. No corrosion. Battery is new. Just swapped it out under warranty.. Now the car had 2 short ground wires connected at one point of time but they were getting hot as well.....smh..... Its the only thing keeping it from cranking.

[avgwarhawk]

Get a new high torque starter. I suspect the starter is drawing to much amps. As someone has stated...the ground goes to the block for best performance.

[NTX5467]

What SIZE/GAUGE is the ground wire???? Wires which are not large enough will NOT carry the necessary "juice" AND will become overheated much easier as there is not enough capacity for what they're trying to do.

If the battery is new, it still needs to be fully charged BEFORE trying to use it. New batteries are not shipped with a full charge, typically . . . usually more like 75% total charge.

In general, many GM engines had flat braid copper ground straps which went from a rear cylinder head area bolt or a valve cover bolt on each side. Sometimes, it was attached to the center air cleaner stud on the carb. Either way, these ground straps were attached to the vertical cowl area. As mentioned, they need to touch "bare metal" areas, not relying upon the screw threads to be the only "bare metal" contact surfaces.

The battery negative cable needs to go directly to the engine. In many cases, they attached to the bracket which held the alternator, with a star lock washer between the cable eyelet end and the bracket. Or it might be attached to an intake manifold bolt or other bolt which screws directly into the cylinder head (but NOT an exhaust manifold bolt!). Same thing, eyelet needs to touch bare metal and have a star lock washer between the eyelet and the engine.

ALSO, there needs to be some of the flat copper braid ground straps between the frame and the car body! One, maybe two.

If there is a 1 inch sleeve spacer between the end of the starter solenoid and the tab which comes out of the starter case for it to attach to, then you've probably got the "high torque", long housing, GM starter. Perhaps it's got some internal issue and pulling too much juice with not much result? Perhaps a newer reduction gear starter might be needed?

On your "new" ground wire, have you checked the internal resistance of it? Cold? Hot? I had a battery negative cable which lost 1/2 volt in it, yet it was original production equipment and looked totally good on the outside, but had an internal issue somewhere. Which was also intermittent! A new factory-spec AC-Delco cable fixed it.

Please advise.

NTX5467

[JohnD1956]

Ok ground wire is new. No corrosion. Battery is new. Just swapped it out under warranty.. Now the car had 2 short ground wires connected at one point of time but they were getting hot as well.....smh..... Its the only thing keeping it from cranking.

Can you expand on your comment a little? Sounds like you had two ground wires from the rear of the engine to the firewall at one time, but they are no longer there? And , am I correct in understanding that you swapped the 1,000 Amp battery with another 1,000 amp battery and the ground cable still is getting hot and the car is not cranking?

[Guest ballafromtexas2]

@ John yes i swapped a 1000 for a 1000 and it still gets hot. When i bought the car it had two grounds running to the battery post from the alternator bracket. The new ground wire which i believe is 4-6 guage is still getting hot. I will try a better ground on the block and frame with the star washers first. From there i will go to a high torque starter.

[NTX5467]

(Curiously) Did this car have some sort of upgraded sound system in it, at one point in time?

Or was the 1000A/hr battery installed to attempt to address the starting issue? For reference, that 1000Amp battery has roughly TWICE the power of the battery which that vehicle came with from the factory.

Just some curious thoughts?

NTX5467

[Guest ballafromtexas2]

No there is no aftermarket system in it. Autozone computer has this as the battery it calls for.

I believe the starter is weak and i will try a different ground location and sand the spot down so there is a good connection.

[NTX5467]

In the world of ACDelco, it takes a "78" series battery . . . with variations from 550CCA to 800CCA, depending on warranty period and other internal differences.

Kind of sounds like you opted for an Optima gell-cell battery. Nothing the matter with them, just that they are very pricey, all things considered.

Please keep us advised on your progress.

Respectfully,

NTX5467

[buick5563]

Kind of sounds like you opted for an Optima gell-cell battery. Nothing the matter with them, just that they are very pricey, all things considered.

Pricey, but great for Texas. Wet cell (acid) batteries seem to die quickly on me.

[Ben Bruce aka First Born]

@ John yes i swapped a 1000 for a 1000 and it still gets hot. When i bought the car it had two grounds running to the battery post from the alternator bracket. The new ground wire which i believe is 4-6 guage is still getting hot. I will try a better ground on the block and frame with the star washers first. From there i will go to a high torque starter.

Your ground cable has to be at least as large as the positive cable.

Ben

[NTX5467]

When I looked at the ACDelco parts website, it listed ground and positive cables of "4" gauge, which is larger than "6" gauge (for reference). To me, the "4" gauge cable is a "normal size" cable, with the "6" cable being too dinky in nature.

Just some thoughts,

NTX5467