Article on adding fusible links to pre-67 Corvettes

[Richard M.]

Re: Article on adding fusible links to pre-67 Corvettes

I seem to recall a discussion a few years ago where the need for a "slow blow" / time delay automotive circuit breaker was mentioned as a possible solution.

Edward, Years ago I used a 30A circuit breaker at the starter source power lead on my '59. I removed it some time later as the heat began to stress the plastic base. I then opted for the 30A fuse at the Ammeter.

Steve, I was going through some of my old documents and diagrams, and I found these pages of notes which I called "1967 Power Path". This was to correct some of the old schematic errors and highlight the fusible links.

Are you sure the Black and Black/White Battery Gauge wires at the solenoid feed and Horn Relay Buss Bar are #18G ? My schematics are showing #16G. You'll also notice the #16G Black at the solenoid uses a #20G link.

[John O.]

Re: Article on adding fusible links to pre-67 Corvettes

Rich,
Yes, the wires to the ammeter on the '64 are 18 gauge, one size smaller than the '67. The main power feed is also one size smaller, 12 gauge rather than 10 gauge shown on the '67. I've seen the '67 wiring diagrams in the AIM, but your diagrams have more info because the power paths are highlighted and fusible links shown. I haven't had the chance to study them carefully, but I did notice the voltage regulator has a 10 gauge wire with a 20 gauge fusible link! I thought the links were always 4 gauges smaller, so that was surprising.
Another interesting thing about these wiring diagrams (my '64 wiring diagram also), notice the main power feed coming from the horn relay splits into 3 wires, the same gauge, somewhere under the hood. Where does that take place, inside the wiring harness? Or is there a terminal somewhere that just isn't labeled in the diagram.
I've put this issue on the back burner for now, but I'm going to look at your diagrams and my wiring diagrams further when I get some time. I think the issue with the ammeter, especially the feed from the solenoid, is that it is a direct connection to the battery at all times, and that incurs some risk. Most other hot wires, even the horn relay to ammeter wire, is behind the main power fusible link which provides some level of protection.
Thanks,
Steve

[Richard M.]

Re: Article on adding fusible links to pre-67 Corvettes

Rich,
Yes, the wires to the ammeter on the '64 are 18 gauge, one size smaller than the '67. The main power feed is also one size smaller, 12 gauge rather than 10 gauge shown on the '67. I've seen the '67 wiring diagrams in the AIM, but your diagrams have more info because the power paths are highlighted and fusible links shown. I haven't had the chance to study them carefully, but I did notice the voltage regulator has a 10 gauge wire with a 20 gauge fusible link! I thought the links were always 4 gauges smaller, so that was surprising.
Another interesting thing about these wiring diagrams (my '64 wiring diagram also), notice the main power feed coming from the horn relay splits into 3 wires, the same gauge, somewhere under the hood. Where does that take place, inside the wiring harness? Or is there a terminal somewhere that just isn't labeled in the diagram.
I've put this issue on the back burner for now, but I'm going to look at your diagrams and my wiring diagrams further when I get some time. I think the issue with the ammeter, especially the feed from the solenoid, is that it is a direct connection to the battery at all times, and that incurs some risk. Most other hot wires, even the horn relay to ammeter wire, is behind the main power fusible link which provides some level of protection.
Thanks,
Steve

Steve, Importantly, DO NOT use the 1964 CSM Wiring Diagram on Page 12-7 Figure 4. It is in very confusing with respect to the Horn Relay Buss Bar and it's wiring along with the mechanical connection representation of the Horn contact feed and output. Additionally, it does NOT show the Ground Lug wire and how it is connected to the horn relay mount bolt.

Look things over when you get time and please check back in before making any modifications.

For the record, many a Corvette owner has replaced wiring and harnesses while following the myriad of wiring diagrams, some of which are wrong and misleading. One such occurrence on a car resulted in a brand new harness being ruined as the owner put the Black Ground wire on the +12V buss bar as the Diagram he used was misleading. It toasted the entire harness.

Rich

[Anthony P.]

Re: Article on adding fusible links to pre-67 Corvettes

Richard what gauge fuse links would you recommend on a 66 at the horn buss, and the solenoid?

[Richard M.]

Re: Article on adding fusible links to pre-67 Corvettes

Richard what gauge fuse links would you recommend on a 66 at the horn buss, and the solenoid?

Tony, I'd have to review the 1966 wiring diagrams which show wire gauge details for each circuit to be able to suggest the link sizes. Standard usage states to use links that are 4 wire gauge sizes smaller(larger #) at the source.

For example, if the feed wire is #12G, then a #16G link is recommended. I don't think I have a 1966 diagram so if someone else does they could tell us.

Rich

[Anthony P.]

Re: Article on adding fusible links to pre-67 Corvettes

Great thank you! I will add the protection at the solenoid, horn buss and fuse the lighter, as I plan to drive the car after not using it for the past 29 years. Thanks Again!!

[Dan A.]

Re: Article on adding fusible links to pre-67 Corvettes

January '67 Service News on page 6 reprinted in the 6th edition TIJM on page 256 has the fusible link info. This was just relayed to me by Tom Dingman over the phone while he is in traffic returning home from an appointment he does not wish me to mention.

[Richard M.]

Re: Article on adding fusible links to pre-67 Corvettes

January '67 Service News on page 6 reprinted in the 6th edition TIJM on page 256 has the fusible link info. This was just relayed to me by Tom Dingman over the phone while he is in traffic returning home from an appointment he does not wish me to mention.

Tell Tom Thanks. I forgot about that. Here it is from my 5th Ed....

[John O.]

Re: Article on adding fusible links to pre-67 Corvettes

Rich,
I have both theAssembly Manual and the Shop Manual on CDs. The wiring diagram in 1964 Corvette Shop Manual Supplement, Page 12-7,Figure 7 corresponds with the wiring on the horn relay that I see on my '64. However the 1964 Assembly Manual, Section 6,Sheet B4, page 146, and Section 12, Sheet A8, page 200, and also the wiringdiagram in Section 12, Sheet D1, page 216 look a lot different with respect towhat I'm seeing at the horn relay on my car. All of these assembly manual drawings show what appears to be a groundwire from the Horn Relay Mounting Bolt to the Voltage Regulator MountingBolt. I certainly can see how someonecould get confused and connect a ground wire to the Horn Relay bussconnections.
My car runs fine withno electrical problems, so I'm leaving it alone for now. I did add the 16 gauge fusible link in the 12gauge main power feed from the solenoid about a year ago. Since all '63-65 Shop Manual wiring diagramsshow the main feed at 12 gauge, I'm about 99% sure that's correct. They also show the ammeter wires at 18 gauge,which started me on this journey looking for 22 gauge fusible links. When I get some time, I'm probably going toadd 5 amp fuses for these wires.
Also, my earliercomment about being surprised at the 20 gauge fusible link in the 10 gauge wireleading to the voltage regulator in the '67: that link is likely used to protect the 18 gauge wires leading from thevoltage regulator. I'm going to lookover a friend's '67 to see what these links actually look like.
Thanks,
Steve

[John O.]

Re: Article on adding fusible links to pre-67 Corvettes

Correction: I meant 16 gauge wires (not 18) that lead from the voltage regulator to the alternator.