Factory location for the negative battery cable?

[71CHEVYSHORTBED402]

One of the bonuses to a full restoration and having a driver of the same sort is reusable parts. The driver is having intermittent starting issues. Though relatively new to barely used, so happens the starter, battery, cables, spark wires etc. won't be reinstalled on the project. Works out rather well.

Less perhaps the old battery, at a glance the primary issue is the negative cable is thrashed where it's grounded, which brings me to.........

What was the factory location(s) for the negative cable connection? See the first image for where it's connected on the driver. If I had to bet it's wrong. For whatever it's worth (probably nothing), this had a factory aux. battery.

The project has A/C as well, but the cable was connected to the top of the frame, also pictured.

Thank you..

[71CHEVYSHORTBED402]

Must have spelled it wrong, because now I see one example in the assm. manual. Straight 6, the cable is mounted to the head. So yeah, some variances. Other than that, came up empty. Both trucks have a 402.

[kwmech]

Negative cable has to go to the engine block. Usually with AC the cable was attached to one of the lower brackets along with a toothed washer and a 5/16'' bolt IIRC

[71CHEVYSHORTBED402]

Originally Posted by kwmech

Negative cable has to go to the engine block. Usually with AC the cable was attached to one of the lower brackets along with a toothed washer and a 5/16'' bolt IIRC

Like the first image?

[FirstOwner69]

My '69 may not be a good comparison since it uses a post style battery, is a 350 and came from GM with the older style (67-mid 69?) small block A/C compressor bracket. However, for the 48 years I've owned the truck, the negative cable has been connected to the front stud/bolt on the right side exhaust manifold along with the front mounting point of the A/C bracket.

Here's a picture from my teardown. Also, note the loop style clamp on the front A/C bracket to prevent harm to the cable.

I don't believe the frame is a good ground point. I'd expect the cable to be grounded to some point on the engine block.

[71CHEVYSHORTBED402]

Originally Posted by FirstOwner69

My '69 may not be a good comparison since it uses a post style battery, is a 350 and came from GM with the older style (67-mid 69?) small block A/C compressor bracket. However, for the 48 years I've owned the truck, the negative cable has been connected to the front stud/bolt on the right side exhaust manifold along with the front mounting point of the A/C bracket.

Here's a picture from my teardown. Also, note the loop style clamp on the front A/C bracket to prevent harm to the cable.

I don't believe the frame is a good ground point. I'd expect the cable to be grounded to some point on the engine block.

Shows how little I know. Couldn't tell you why the block is better. I'd have thought the frame would be an ideal ground.

Hard to get a "picture" for what you got going on there Jim, but if I get your meaning, the image below might illustrate correct placement on a 402 A/C?

That clamp is noted. As opposed that, there's another hose retainer at that point on the driver. I have a few of those clamps off the 71. They were removed with the rest of the A/C, long before I was paying attention.

Side posts are stock? I had the impression my top posts were original, for no other reason than a looks right "secure" clip on the cable I've had, at the starter connect.

[Stocker]

Factory side post battery on my '72 K20. Looking at the front of the engine, the negative cable connects to the far left-hand bolt of the A/C bracket -- just a bit lower than center of A/C pulley. HTH, sorry no pic. BTW mine is a 350 engine, I see yours is a 402 so it may be different.

[FirstOwner69]

Originally Posted by 71CHEVYSHORTBED402

Shows how little I know. Couldn't tell you why the block is better. I'd have thought the frame would be an ideal ground.

Hard to get a "picture" for what you got going on there Jim, but if I get your meaning, the image below might illustrate correct placement on a 402 A/C?

That clamp is noted. As opposed that, there's another hose retainer at that point on the driver. I have a few of those clamps off the 71. They were removed with the rest of the A/C, long before I was paying attention.

Side posts are stock? I had the impression my top posts were original, for no other reason than a looks right "secure" clip on the cable I've had, at the starter connect.

As I understand it, they started using side terminal batteries in 1971.

I believe the block is the better ground since the starter (high current draw) is also grounded to the block via its mounting bolts. The frame is grounded to the engine by relatively small gauge grounds.

Here's a zoomed picture with the battery cable traced with white. Not which position in your picture is right, but I'd probably go to #2.

Wow, my 3000th post!

[Stocker]

Dunno how to do all the fancy pic manipulation but fwiw and for those with a 350, using this pic my neg. cable goes to the bolt just below the green & black electrical connector on the compressor.

[Steeveedee]

On my truck, the ground cable was bolted to the front of the block at one of the holes "around the corner" from where the fuel pump is mounted. When chasing down hot slow cranking issues, I ran a new cable all the way back to one of the starter mounting bolts, eliminating every possible high resistance connection in between. It starts almost all the time hot, unless it is really hot, like 230°. Note that I also installed two more ground straps between the block and the frame, first, which helped a little. GM counts their cost in .1¢ increments (in those days), so having a cable 2 feet longer would not be happening. That, and paying more labor to install a longer cable on millions of trucks would have been a cost issue. I also put on a mini starter, but that actually didn't help that much.

[71CHEVYSHORTBED402]

Always an education......... Well, my 72 will have top posts (ha!), because that's what came off the 71. I'll run side posts on the 71.

Didn't see this until now. A bolt is missing. Might be the correct spot on a 402?

[FirstOwner69]

Originally Posted by 71CHEVYSHORTBED402

Always an education......... Well, my 72 will have top posts (ha!), because that's what came off the 71. I'll run side posts on the 71.

Didn't see this until now. A bolt is missing. Might be the correct spot on a 402?

I think you nailed it! At least that appears to be the location identified on page 1A-27 of the 1972 factory service manual. Do you have the manual?

EDIT: Same picture, page 1A-25 in the 1971 service manual.

[71CHEVYSHORTBED402]

Originally Posted by FirstOwner69

I think you nailed it! At least that appears to be the location identified on page 1A-27 of the 1972 factory service manual. Do you have the manual?

EDIT: Same picture, same page in the 1971 service manual.

I have the 1971 manual. 1A-27 in this manual only shows an image of the dryer sight glass. I missing something?

Are you saying the "missing bolt" per the image in post 11 is for the cable connect?................Ironically, it turns out I have that bolt off the 71. It was still attached to the bracket. The nut is nearly flush the end of the bolt, so not sure there's room for the cable connect..................... I say ironically, because apparently, I lost most of the A/C bolts. Beauty of having the driver is I know just where to get them.

[FirstOwner69]

Oops... should have said page 1A-25 in the 1971 manual. Sorry. Corrected it in post 12.

Yes, the missing bolt.

[franken]

Not sure if its of interest, but the right way electrically is to make the electrical path as short as possible. That means the big ground should be as close to the big positive where it connects (starter) as possible. Frame and alt bracket--bzzt-wrong. Best id to the block or a starter bolt.
What GM did the day the truck was built is fine 50 years ago (12 month warranty) and for a concourse (sp?) resto, but not a driver today.
Or, make damn sure every wire, nut, bolt, switch contact, connector and thread between the battery, starter and solenoid are clean and free of excess resistance end to end. Exactly, you can't do that easily.

Sorry, invented my own question to answer...

[painterljp]

Call American auto wire. They will tell you the factory specs on the negative cable and it will only reach some of those places. That should give you a better idea of where it goes?? We have a 68 gmc w/o ac. Got the spring cables from American auto wire. Everyone said the positive top post went to the radiator side but they were wrong. The accessory wire that goes into the fuse block on fender is only 7.20 inches long. General motors did not intend for you to have to butt connector. the wire to run to fuse block. Is plenty long enough to reach with positive battery post to fender side. So that answered that. Also looked it up in assembly manual under wiring diagram. Positive is truly to fenderside. Not radiator side.

[franken]

The low current wire to the body should have a fusible link. We learn why when the battery to firewall harness fries.
I think the OPs question is different. Again, understand what you're doing and it get's easier to make a reliable system that won't kill itself.

[71CHEVYSHORTBED402]

Originally Posted by FirstOwner69

Oops... should have said page 1A-25 the 1971 manual. Sorry. Corrected it in post 12.

Yes, the missing bolt.

Son of a gun Jim, I looked at that page, but wasn't wearing my glasses. BINGO, "clear" as day, connects to the bracket nearest the fuel pump. VERY COOL. Thanks for walking me through this

You guys motivated me to figure out the A/C system & inventory for the 71 project. I have all the brackets, but many of the bolts were missing. Got em now though, thanks 72. She got the new bolts.........backwards thinking.

Took the A/C off in 1993 and wasn't paying attention Shame too, before that the truck was truly unmolested (edit - less a real bad paint job.) Stupid engine throwing a bearing. Ha......Lost my job the same day, & dog two days later. Alright, I'll stop.

[71CHEVYSHORTBED402]

Originally Posted by franken

Not sure if its of interest, but the right way electrically is to make the electrical path as short as possible. That means the big ground should be as close to the big positive where it connects (starter) as possible. Frame and alt bracket--bzzt-wrong. Best id to the block or a starter bolt.
What GM did the day the truck was built is fine 50 years ago (12 month warranty) and for a concourse (sp?) resto, but not a driver today.
Or, make damn sure every wire, nut, bolt, switch contact, connector and thread between the battery, starter and solenoid are clean and free of excess resistance end to end. Exactly, you can't do that easily.

Sorry, invented my own question to answer...

I read that business searching for the factory location. Makes sense. This is a full restore and will remain clean as long as I have a breath. Though I may do as suggested on the driver. She gets a full tune-up. All fluids have been changed less transmission (soon), "new" starter, battery, cables, spark wires, ignition cyl, locks, some cosmetics, etc........She's kind of dog in a rust respect, but I like her a lot. Gives me a break from the actual restoration.

[71CHEVYSHORTBED402]

Originally Posted by painterljp

Call American auto wire. They will tell you the factory specs on the negative cable and it will only reach some of those places. That should give you a better idea of where it goes?? We have a 68 gmc w/o ac. Got the spring cables from American auto wire. Everyone said the positive top post went to the radiator side but they were wrong. The accessory wire that goes into the fuse block on fender is only 7.20 inches long. General motors did not intend for you to have to butt connector. the wire to run to fuse block. Is plenty long enough to reach with positive battery post to fender side. So that answered that. Also looked it up in assembly manual under wiring diagram. Positive is truly to fenderside. Not radiator side.

No kidding (page 993 in manual). I always thought it was the other way around, and yeah, mine was on backwards. What about side posts?

[Stocker]

^ On my K20 with sidepost battery and a 350 (it may be different with a 402) -- negative is on fender side, positive is on radiator side.

[FirstOwner69]

painterljp is 100% correct regarding the orientation of the posts on top post batteries. My '69 came new with the posts toward the core support. In other words, the positive is toward the fender. I always thought that was odd (other than allowing a short wire run to the junction block) since, if the battery weren't secured, the posts might tip against the core support when braking hard. That would not be cool.

Not sure about the side terminal batteries, but I think they are all made with the terminals positioned so that, when installed correctly, with the terminals away from the core support, the positive would be away from the fender as Stocker said.

[71CHEVYSHORTBED402]

Originally Posted by Stocker

^ On my K20 with sidepost battery and a 350 (it may be different with a 402) -- negative is on fender side, positive is on radiator side.

Same with my 72 402.

[71CHEVYSHORTBED402]

Originally Posted by franken

The low current wire to the body should have a fusible link. We learn why when the battery to firewall harness fries.
I think the OPs question is different. Again, understand what you're doing and it get's easier to make a reliable system that won't kill itself.

I give, what's a "low current wire to the body"? You reminded me however, if there isn't a fusible link to the starter I should probably add one. EDIT: WRONG. The fusible link is at the junction block.

[FirstOwner69]

Originally Posted by 71CHEVYSHORTBED402

I give, what's a "low current wire to the body"? You reminded me however, if there isn't a fusible link to the starter I should probably add one. Especially for this driver. The wires were/are a mess in places. Add a rusty cab........yikes.

The cable to the starter does not use a fusible link.

EDIT: By low current, I assume he means low amps.