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1968 fusible link

Started by Jd cadillac, March 07, 2018, 10:25:29 AM

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Jd cadillac

There are two fusible links that are in need of replacing on my 68 De Ville. One goes to the starter and the other goes to the alternator. I want to replace them with an actual replaceable fuse. Does anyone know what size they are ? Or what size fuse I should install ?

    Thanks, Jeff
68 Coupe
65 Coupe
64 Coupe

Jd cadillac

I found out more information. I don't want to install a fuse in that situation. Reinstalling that correct fusible link is the way to go. Does anyone know the correct wire size for that situation ?

       Thanks
68 Coupe
65 Coupe
64 Coupe

bcroe

There is wire available just for this purpose.  Basically it is spliced
in about 6 inches, 4 gauges smaller than the wiring being protected. 
It has special insulation to contain metal if it gets blown through.  I
keep it on the shelf in about 6 sizes.  My feeling it is more efficient
and reliable than a regular fuse, more compact, and doesn't require
waterproofing. 

Bruce Roe

TJ Hopland

I have not looked at a 68 shop manual recently but the slightly later ones list the wire gauge sizes on the main electrical diagram. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Highwayman68

Please be more specific on which wires and physical location of the fusible links you need to change and I will validate the proper size from the manual.
1968 Fleetwood Purchased in 1981

DeVille68

very good topic. Where can I get those fusible links?
Parts supplier? Ebay?
1968 Cadillac DeVille Convertible (silver pine green)

bcroe

Quote from: DeVille68very good topic. Where can I get those
fusible links?  Parts supplier? Ebay?   

There are some already made up with a lug on one end, or you can
order a roll of wire (4 gauges smaller than the wire being protected).   
I  have taken a few from the junk yard.  Try also
DORMAN HELP
DORMAN MOTORMITE FUSIBLE LINK WIRE
AMAZON
www.motormite.com

good luck, Bruce Roe

35-709

NAPA.  Probably Advance Auto Parts (they took over Carquest).
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

DeVille68

ok, thanks.

So, according to my shop manual there are three fusible links from the starter solenoid bat-terminal.
16B goes to 10 B/R (fuse block main) and 12 OR (to blower relay)
16B goes to 10 R (to ignition switch)
18DG goes to 14 Y (to the light switch)

On the generator bat terminal:
18DG goes to 14R (to the voltage regulator)

The numbers catalog lists a few fusible links (14, 16, 18, 20 gauge) in category: 2.530
but does not give a length?

So I need 16 and 18 gauge fusible links. How long should each be?
(I cannot check on my car, because they are all missing and have been replaced with normal wire  ::) )
1968 Cadillac DeVille Convertible (silver pine green)

TJ Hopland

I bought rolls of the stuff at my local Napa.   I think they were like 20' rolls and came in a little plastic dispenser pack.   In my case they were out on the main floor on one of those spinning displays with other wire and electrical dodads.    Later today I will see if the card with the part number is still with any of them since a quick search doesn't turn up what I'm looking for. 

I have almost always had something to copy so I never was that worried about the length.  Bruce said 6" but I'm thinking they were closer to 12" for me.  I'm not sure how critical the length is, it may not be critical for the function within reason.   It may just vary for what is convenient.    If there was already a splice or a junction at 14" why run 6" of link wire and then splice to 8" of regular wire.   
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

bcroe

Quote from: TJ Hopland

I have almost always had something to copy so I never was that worried about the length.  Bruce said 6" but I'm thinking they were closer to 12" for me.  I'm not sure how critical the length is, it may not be critical for the function within reason.   It may just vary for what is convenient.    If there was already a splice or a junction at 14" why run 6" of link wire and then splice to 8" of regular wire.

Never ran tests here, but perhaps the minimum length is to
keep the much larger wires at the ends from draining away
the heat and preventing it from doing its job.  The ones I see
are usually about half a foot.  Likely it would work at much
longer lengths, but the the resistance per foot is going to
be 2.5 times the rest of the run, so its not helping efficiency. 
Now I have to go measure some to see that it isn't even higher. 
Bruce Roe

DeVille68

would be very nice, if you guys could compile  the length of those three (or four) fusible links!

Best regards,
Nicolas
1968 Cadillac DeVille Convertible (silver pine green)

TJ Hopland

How far is it now from the starter to where the original wires start?    If its between 6 and 12" I would just go with that length.   If its like 2' then I would splice some normal wire in.

Does 68 have a connector in that harness?    In 73 I believe that connector was the transition between the regular and link wire.   I don't think they used that connector for very many years, seemed to be a common area for problems.  I think it was 6 pins.  3 for the link wires, one for the I terminal, one for the S terminal, and a spare. 

I will go out now and see if I have any part numbers. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

TJ Hopland

Found them, reason search didn't turn them up is the short description is 'primary wire' which seems to be what they call all their wire.   

Napa part numbers:

16 gauge is 785832 and is dark grey color.  18 is 785825 and is a lighter blue color.   

Both are 3m/10' lengths in a little dispenser pack and come up under $10 and in stock at my local store.

I think they have 14 gauge also but I used it all up on various projects.   
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

bcroe

#14
One quick test here, looks like fusible link wire is about the
same resistance as regular wire (of the same gauge), just
has special insulation.   20 gauge measured out at around
0.01 ohms per foot.       Bruce Roe

TJ Hopland

That was my conclusion too but discovered I need new meter leads so I wasn't sure.

I did some searching and 6" does seem to be a minimum.   I saw several references to GM 9" but not sure what era.  Saw a couple in the 12-14 range but those seemed maybe related to Ford trucks. 

If it was me as long as the gap to fill was between 6 and 12 inches I would just fill it.  If it was 16" I think I would split it and go with 8 regular wire to match the original and then 8 in link wire. 

If you are not building a show car some of that modern heat wrap where the harness goes around the exhaust manifold would be a good idea. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

DeVille68

#16
Quote from: TJ Hopland on March 11, 2018, 04:29:02 PM
How far is it now from the starter to where the original wires start?    If its between 6 and 12" I would just go with that length.   If its like 2' then I would splice some normal wire in.
Someone removed my fusible links and put butt-connectors in-between. From what I remember the new incorrect connector is at least 20'' away from the terminal. But I have to check again when I am working on the car.

Quote from: TJ Hopland on March 11, 2018, 04:29:02 PM
Does 68 have a connector in that harness?   
From the shop manual and diagram I can tell that there is no special connector, those wire were spliced together.

Would be nice if someone could try and measure his original or replaced fusible links. Thanks! :-)

Best regards,
Nicolas
1968 Cadillac DeVille Convertible (silver pine green)