silverriff

Alright after reading about some of the possible causes of that hard starting I had, I am wondering about grounding straps and battery cables. I have a ground from my battery to the block, but no visible ground from the block to the frame, as the original braided strap was cut when the engine was transplanted and it was never replaced. I am going to run a new strap, my question is does it have to be a braided strap or can I just use a length of battery cable? If it is already grounded through the mounts, can you have too much ground? I am also going to replace the battery cables...which gauge should I be using? My local parts store has premade 4 or 6 gauge. Which is better to use?

citcapp

Can't have to much ground. The braided strap from the engine to the firewall was used for engine movement and is very flexible so it will not break this also bonds the engine to the body. Over time with a lot of engine movement a normal copper wire will break strands. The ground from the battery is best routed to a ground post on the body near the battery then to the engine block this provides the shortest route for a ground path. There should be another braided ground strap from the frame to the body as well. The #6 wire is fine for short runs when the battery is close to the starter connection. #4 is better as there is less resistance, given the choice I would use the #4. I have found that by doing the above system of grounding that even on the hotest of days when the engine is up to temp the starter never bogs dowqn on 10.5 compression 455.

mugzilla

Get an investment grade set of cables ...

Factory style with spring clip Pos terminal ...

Factory location for the block connection for the ground is behind the power steering so you have to remove it ...

When you are done you will have an installation that will add to the value of your cassic ...

The factory ground cable has a nice ground wire for the body by the lights which is good. Make sure your block to firewall ground is hooked up ...

silverriff

Upon closer inspection, the braid from the back of the block to the firewall is there. It is all ratty and frayed, and needs to be replaced, bit it is there. There is nothing going from the block to the frame, and the battery ground goes only to the stock block location behind the PS pump. It doe not have the little secondary tail that goes to the core support, although part of the original ground is still screwed into the support, it was just clipped off the battery. So it seems like a weak ground may be the culprit for at least some of the funky issues I have been having. I will replace the 2 braided straps and make sure they are good and strong. I am pretty sure the premade battery cables do not come with that secondary ground, but if I get a new block to frame braid, should that be good enough? Or should I find a way to rig up another little ground straight from the battery to the frame? The good repo cables are not in the budget right now, maybe in the future sometime. Also I saw for the hot cable that the premade ones have a fusible link connector for the pigtail hot wire to the alternator. Would I just need to solder on the rest of the wire to the alternator? And if so which gauge is that pigtail supposed to be?

wmachine

Yes, they do make replacement neg cables with the extra small side wire.
I disagree with the original spring type cables being the best best, as they certainly are not. The bolted clamps are more secure in the short and long term.

Trivia question: What production year started the OEM side mount battery terminals? (I never would have guessed right)

silverriff

Yeah I finally found a picture of the premade cables with the pigtails already on there. Damn Autozone and Advance.... does anyone know the magical secret of how to search their websites without having to put in your car info? I always greatly limits my search results if I am not looking for something OEM for my car. Everytime I searched for the battery cables they were just coming up with a very limited selection of sidemount cables but I have, and will most likely replace them with top mounts, but since they are not stock for '72 I can't search though the inventory of what they have available. And my guess for your trivia question would be early 1900's.... 1905?

BlackGold

There is absolutely no reason to electrically connect your frame to the battery, engine, or body. The frame/chassis has no electrical components.

The braided wire between engine and firewall is not to ground the engine. It's to ground the body. The "true" ground for the car is either the negative terminal of the battery (when the engine is not running), or the case of the alternator ( when the engine is running). Everything electrical needs a good path back to those two items.

Lady72nRob71

Lots of good info here.

The engine mounts do not provide a good ground, as they are normally rubber encapsulated. I have heard of a starter grounding through the driveshaft when the block was not grounded, and the yoke was damaged as a result. Many body repair guys do not understand electrical stuff.
Bad engine grounds can also lead to attempting grounding though engine coolant, causing premature radiator failure.
Battery to block is most critical (and most subject to failure) as the starter has the highest current draw.

Replacement braided straps could be had from a variety of older vehicles at little cost.

From what little i know, 1972 was the first side post battery used on the Cutlass series. (I currently have incorrect top posts.)
...........am I in for a surprise?

As for the frame, I think there is a reason it should be grounded, either for corrosion prevention, radio noise reduction, or something.
My old Furd has a factory copper strap to ground the hood, and there is no light or anything on there!

oldsonharmont

Ater pricing repop cables I had some new ones made up locally. Brand new cables, crimped on terminals and shrink wrapped connections.
Very nicely done, and only half the price of the repops. Also added a short jumper from the neg. terminal to the core support. I can post pics if you're interested.

silverriff

Pics would be great if you have them. I found some brand new grounding straps at my local advance, $4 bucks a piece, not too shabby. But I wasen't impressed with their selection of premade cables. Price was right at about $12.00 for a 5 ft pos. cable. Where did you go to get yours made, an electric shop or something like that. I know my normal mechanic wouldn't do it.

oldsonharmont

I'll get some pics posted in the next few days, and you can let me know how you like 'em.

Olds64

I put pre-made O'Reillys battery cables on my 71 98. They work fine.

Jamesbo

Wmachine, Rob, I think it was 71 wrong/right?

mugzilla

do boat batteries count ...

55 Chris Craft ..?

wmachine

Yes, GM went to the side post batteries in '71. Much earlier than I remember it being!