knock on wood here..... no problem with MSD products except corrosion of the module in the distibuter

I realize you are adding resistance and fattening up of the wire is the counter, but what about the original skinnier section being a weak link?

Yes, I am not concerned at all about driving in the rain, I am concerned about condensation, especially in the winter when I light off the 180000 BTU salamander heater to work on the car.

Also, you said you have the POS wire going to the CB on the firewall. Same here, but mine is to the top terminal (after the juice goes thru the CB). i think that if we went to the bottom terminal that it would be closer to what MSD had in mind.

That small black ground wire going to the firewall from the engine head is starting to worry me also. I have a bunch of braided straps. What do you think about putting a nice fat one there instead of the black wire?

Rick,
I like and believe a little overkill is a good thing...better safe than sorry. I have always sprayed down battery connections with that colored grease, but never the other connections, I think that is a great idea, probably will use dielectric grease though.
As far as the grounds go, I do not have FI or an ECU but I still think the multiple grounds is a good way to go. What I have now is battery to frame in the back. Small black wire from pass head to firewall. 1 " wide braided strap tranny to frame. I would like to run an addition grounding strap engine block to frame and driver head to frame. Maybe even the manifold to frame. Is it OK to run multiple ground straps or wires to the same grounding point on the frame?

Any idea what that rating is for CB on the firewall . Since my POS MSD wire is going there, is that basically acting the same way your fusible link is doing on your set-up?

Planned on soldering and using shrink tube on the splices. Do you think that is necessary on the terminal ends also. I always have heard that a good crimp was sufficient?

Thanks...Dave

No Cb in my curcuit
 

davids2toys Dave,We all have different ways of installing and running our cars. I have been running in the rain. Water comes in under the front windshield gasket and soaks everything in the car. Both my ECU and MSD are getting wet. I have sealed both with RTV around the box seals and at the wires where they go into the modules. I use Packard connectors,(a GM thing, who I work for over the last 30+ years). To date, all connections have remained clean and good contact. Side note, if you get into a problem with checking out curcuits and they have packard connectors, GM recommends replacing them because of causing a weaking connection. We do a drag test to see if the connector is ok, No drag replace, Bending of terminals is a temp fix and doesn't last over the long term. Have to remember that the more amps that go through a connection the more heat is produces and we all know the heat causes metal to bend or weaken.
I wouldn't use a CB for this power curcuit. There shouldn't be a failure of the fusible link unless a major ground out. It will also be stronger on startup spikes on that curcuit. We have used them for 50+ years. I have 2 on my 79 TA that work just fine with 147,000 miles on them in all weather.
Reason for not using CB, Main one is a wire rub through, I have seen this, wire coating rubs through on metal part of car and arcs out to ground. CB blows and resets, wire still grounded. This can go on and on until the CB contact points inside for smoked or burnt off. Alot of wiring damage can be caused. I have seen it and been there once. I learned my lesson.
If you hook your power to the starter soleniod battery side and a ground wire to the heavy ground wire on the block, put wire protective plastic covers on them and ( VERY IMPORTANT ) may sure them are CLAMPED and wiretired to control movement, I see no problem.
Connections, as long and you use good ones, soldered and sealed or shrink tubed, you should never have a problem. Side note, some guys use KUNG FU grip to crush the connectors. You want them tight and soldered. Tightned to a stud or bolt holt but again not overtighten to crack the eyelet.
If you do good basic work, I see no problems.
Other notes Dave don't let the resistance thing run away with you. As long as you are in the .3 ohms and or less you have a good connection. .1 is idea. Doesn't always happen depending on type of wire, wrap of wire and gauge. Lower the better.
As far as MSD for the last 20 years they still gan't get the correct info on where and how to install a MSD box. I was told, no heat area and no vibration. Reason for mounting under glove box. Good freash air and out of harms way. They still have problems with caps and rotors.UGH!!!!.
YOu would have to check with Bob at ERA but I think the ground wire we use to the back of the head is for ground on all the dash lights and relays.
Bottom line, there is a little guy who sits on your shoulder and every once in a while he says, DON'T do that, or That's not RIGHT, you know kind, like the wife or girl friend and GOD is watching this also:eek:. Listen and recheck or get a 2nd opinion. %/ I think I have tryed to cover it all for you. You are going in the right direction with the right ideas. ;):) Rick L.

Dave, don't over-think the MSD installation. The specs from MSD say the box pulls 1 amp per 1000 RPM. If you add a 50% safety factor to that the most that box will ever draw, and then only for a brief amount of time, is ten amps. That's it. If you run a 10 gauge wire to extend the leads that come with the box you'll be just fine. The internals of the circuit breaker add a small amount of resistance but, again, that's not going to amount to a significant factor.

Remember, MSD gets to issue one set of instructions, that will have to be interpreted by tens of thousands of people, doing tens of thousands different installations. Everything from mama's Biscayne to borderline-NASCAR revvers. I wouldn't worry about the condensation at all but, if you're obsessing, drill a couple of pin holes in the top (which is the bottom in an upside down installation).

Regarding the circuit breaker versus the fusible link, both have their respective advantages. I run the MSD standard 50 amp circuit breaker, but I have to agree with Rick that a fusible link is probably better, but a breaker is just a little more convenient. The reasoning is that if either one blows then you have a pretty serious problem. Now, if that problem is just transitory, and basically innocent, like a dropped wrench on the starter solenoid, then a circuit breaker is great. It just resets in a couple of seconds and you say "whew, I need to be more careful." With a fusible link you're saying "goddammitt, now I have to cut out and replace that fusible link -- that shoots the day." On the other hand, if you have a persistent serious short, the circuit breaker fires on and off until you can get to your battery cut off switch. The fusible link blows and your ohm meter tells you that the wire is shorted and you have a problem. Plus, circuit breakers weaken over time and pass less current before tripping when exposed to high underhood temperatures. That said, I run an upside down MSD box in the passenger foot well with no drainage holes and I feed it directly off the protected side of the 50 amp master circuit breaker. But, I don't drive in the rain and do no serious racing. Now, if I did heavy duty rain racing, I would have a waterproof box installation and run fusible links at the alternator and at the battery feed. I hope that helps.

Rick and Patrick,
Holy crap, I am getting educated big time...my head hurts:3DSMILE:
I understand everybody has their own way and interpretation of the best way to do things. I consider myself very fortunate to be able to get educated by people who are much smarter in areas I am not so swift in.
So after after researching what a fusible link is, I like that idea. It said to run 4 sizes under the wire to be protected. So if I am using 10 wire, then use 14 ga fusible link wire? Can you put this on the neg wire or just on the positive? Or both? Rick, you said you hooked up your POS with a 40 Amp fusible link. I am only seeing fusible links in wire sizes ex:14 gage...no specific amp rating. Did I miss something here?
My plan at this point is to lengthen the neg wire back to the trunk where the neg off the battery grounds to the frame. I think I will not lengthen the 12 gage POS wire but just connect it to the "unprotected" side of the CB on the firewall or the hot side of the solenoid with the fusible link(16 gage) in between 12 gage POS wire and the connection point. Does this sound OK? I also read no longer than 9' for a fusible link. Is shorter better?

Patrick you are saying you are running an MSD 50A CB? I thought you were using the one on the firewall from ERA( I am presuming it is from ERA). I do not know the rating on this CB.
Nice idea with the pin holes...maybe a #50 drill? 1 hole on each end? I need to think about it a little more because that will let the air in easier including the warm and cold extremes, it might make condensation easier to form. Do you think there are any electronics right next to the cover that I might hit with the drill? I would think not, but I never had one apart. as far as what Rick said about sealing the cover, I know they are dead set against that and the fact that is is not sealed should be an air source for evaporation I would think.
I know you guys know what a drip loop is, we use them all the time in helicopters. So with water coming in as Rick described, a drip loop would be great as the water would drip off the wire before it followed the wire into the box. So I think i will make sure every wire going to the box has a drip loop and I might take a blob of clear RTV and put it at the wire entry points into the box as Rick suggests. Maybe even some duct tape over any unused ports in the box.
I always thought/assumed the wires and box did not get wet in the rain, but I have never checked. I have only been caught in the rain a few times, but as Rick said, it comes in everywhere and for it to follow the wires right into the box seems very possible.

Also got educated on the Packard connections. Looks great if it is part of your job and have all the necessary tooling. If I was building a new Cobra I think I would definitely consider going this route!

Dave

They are one in the same. That ERA furnished master circuit breaker that is on the firewall right next to the starter solenoid is rated at 50 amps.

Now here's another option that you might want to consider. You can replace that ERA furnished 50 amp "auto reset" circuit breaker with one that requires manually resetting. A little button pops out of it when it throws and you have to manually push the button back in -- just like the circuit breakers in your house.

Fusible Link Info
 

Here's info on fusible links, their ratings, etc. After I took time to think about it, I'm pretty sure I've never installed one in my life. Certainly not on the Cobra. Weather Pack Fusible Link

Places to get fusable link kits or wire
 

davids2toys Dave short story this time, we covered all the other info.
Fuse links or any power side of a curcuit get a protector, CB, fusable link, fuse, a bubble gum rapper. (Save this for another time):rolleyes:Places to get different size links in kits or wire spools'
Wiring Products 1800-549-0243 kit # FLW 12 GA Kit

White Products 1440-871-0800 service packs, got my stuff here.

Madenterprises 1559-539-7128 FL12 kit

Napa has bubble rapped kits, no 12 gauge kit or larger.

Ground wires don't need fuses because 98% of the time they are grounded and a wire rub through will not change anything to a cucruit. There is a Major catch here, alot of new systems including injectors are using the ground side to turn on and off curcuits and not the power side. Blower motors in some cars have direct power to motor and a series of resistors in a row that have different resistance to control the speed of the motor. Again another story.

Choice is yours. Overkill has worked for me. I have no luck with things so backup plans are also in play. I do like CB in some curcuits, the big old sytle ones from the 80's. The new minies ones are in alot of our new cars. There seams to be a safety built into them if a curcuit blows it more than a couple of times. They will not reset. Some are also smoked after a couple of shorts. I like the K.I.S.S. system, and it's working pretty good. Rick L. class is out, and I have no class. Later:rolleyes:;):):D

Cute Rick...LOL
This is the job I tackle next. My new slave, fire-sleeve and clutch Master cyl came yesterday. After I get that all finished, on to this MSD thing.
I called White Products earlier today. The woman's name was Rose, she was pretty knowledgeable.
I told her about the fusible link and that I heard to go 4 sizes under the wire I am trying to protect. She said this is true. She told me I would want to protect the 12 wire rather than the 10 wire used to extend the 12 wire. Not sure I agree with this. So that means I would be buying a #16 fusible link wire. As I said ealier, I probably will not extend the POS MSD wire, just hook it up to the hot side of the solenoid with the fusible link wire in between the two. Any idea how long to make the link. I have read no longer than 9". Could you actually go to short? So how long should I make or does it not even matter?
So here is the weird part. I told her what you said about the 40 Amp fusible link wire that you used. She said a 16 gage fusible link wire is equal to 75 Amps, a 14 gage fusible link wire is equal to 110Amp. I asked her what wire would equal 40 amps and I believe she said 22 gage. So what am I missing here because that is 10 wire sizes down, not 4 as recommended???
Please straighten me out, I want to order parts but confused on this information
Thanks...Dave

Pretty cool item.
This is what I found. They all have plastic mounts. Don't these circuit breakers need to be grounded like the metal mount type 1 auto reset presently on the car?

Manual Reset Circuit Breakers - with Bracket

http://www.ebay.com/itm/171596826353

http://www.wiringproducts.com/50-amp...gle-mount.html

I will still hook up the MSD POS wire with a fusible link as Rick suggested and you agreed. In addition, change out the ERA 50 amp CB with the manual setting type

What ever makes you happy and safe
 

davids2toys Dave I don't beleive in 100 years that the MSD 6AL draws ONLY 1 amp for every 1,000 rpms. Why the heavy 12 gauge wire then???
Remember I said overkill, THis fusible link is also like a resistor and you loss ampage going though it. IT's like a funnel you are pouring a fluid through, pour slow and you have no backup, pour fast and the funnel fills. Same applys for electrical curcuits. This is why good connections are so important.
Curcuits are tested with a steady load, not with startup spikes. Your fans on your car my draw 15-18 amps but the startup may be as high as 40-60 amps for a split second. For this second the ampage is way beyond the curcuit limit. The fuses are slow blows and are the safety protectors of the curcuit. This only last for .10 of a second. Over time a fuse or link will weakin from the heat or spike loads. I don't explain theory very good, too many days of missing school.
Any way Yes a 16# link would be ok, just no for me. The link will still blow if a dead short happens. With 12 Gauge on this curcuit I don't believe in having any problems. Other power curuits, yes with running a lighter gauge fuse, depending on the wire of that curcuit. I like to match up gauges.
PS stop finding things on the car. You are 3 hours away, any more problems, I am sending Pat to fix your car.:eek::rolleyes:;):)

I'll have that thing up and running in no time -- using nothing but duct tape and coat hangar wire. No fusible links -- just a few fuses and one measly circuit breaker.:cool:

Rick, I am doing multiple jobs at the same time so I have multiple issues, sorry. I am not a 1/2 arse person , I like to do things right the first time and avoid learning stupid, expensive, potentially disastrous lessons.
You explained some of this well. I do understand about start up spikes vs steady running use and the importance of good connections.
Maybe I am an idiot but I still do not understand what you used when you say "40amp". Was this the fusible link wire I am looking at online? As I said, 40 amp equals a 22 gauge wire, so I am still not understanding what you used. So are you saying 16 gage fusible link wire(75 amp) is OK, but not for you? You would go with the 22gage(40amp)fusible link wire???:confused:

Yes, only 3 hours away...you are more than welcome, why don't you and Patrick come up and we will have a nice BBQ and play with my car...LOL. Also show you some awesome cobra driving roads. I have a lift if you want to put your cars up in the air to do any work or service

PS: Don't forget the duct tape Pat:3DSMILE:

As you know, but I'll say it anyway, when an electric motor is turned on, there will be an initial, very large "surge" of current that will exceed the rating of the fuse. But, the fuse or circuit breaker won't blow because it takes a little more time than that to heat up the element and cause the trip. This is normal. For a dramatic demonstration, go here: http://www.clubcobra.com/forums/all-...t-breaker.html and skip down to my post with the pic of my inductive ammeter set to measure the surge current of my starter motor (and it's the old style big guy that went in to five billion Ford cars). Yep, over 900 amps. So you know, any of our cars, even the ones with the little tiny 60 amp alternators like mine, can still crank out hundreds of amps, which can create enough heat to melt any of your wires. In choosing a fusible link, the reason you go with a gauge rating, instead of an amp rating, is because you are protecting the wire itself, as opposed to the load. A fuse will protect the load, so it's handy to just double the amperage for the load and set that as your fuse value -- even if you're feeding the load with a very, very large wire, or a small wire. Now with a fusible link, you ask yourself "what's the maximum amperage that wire will handle" and then place a fusible link along the line that will handle less than that but, of course, still exceed the combined load that is being served by the line itself. Most car wires, if you short them to ground, will carry quite a bit of amperage before they burn the insulation up -- much more than you might think.

... and the MSD box really does only pull 1 amp per 1000 RPM. Here's a thread on the MSD forum where the MSD tech talks about it: https://www.msdignition.com/forum/showthread.php?t=4242

... and the box itself has a 15 amp fuse soldered to the board itself -- so there's no reason to add a fuse to your MSD box load because they've already done it for you.

But if curiosity has gotten the better of you, and you just have to know how much current will blow a typical fusible link, or else you just won't sleep at night, I copied this chart for you.:D

http://www.clubcobra.com/photopost/d...usiblelink.jpg

Pat, as usual, great posts. That MSD thread was good!

OK, so if it has a circuit breaker on the board that would explain why they want this to go directly to the battery thru no fuses or circuit breakers of any kind. So why are you running yours thru the protected side of the 50A CB? Why do we need to run thru anything at all? Is there any risk in doing what MSD says to do? I like safety, so I am more than willing to run this fusible link if it is a better installation. I just need to know how long to make the link?

It is not that I need to know what will fry the fusible link wire at all. I just need to know what to use for this application. So then my question is still this...per your chart, is Rick using an 18 gage (40 amp) fusible link to protect his 12 gage Red POS MSD wire?

Dave

The reason I feed the MSD box off the protected side of the master circuit breaker is not to protect the box itself but rather to protect the line that is feeding it. The onboard 15 amp fuse protects the box. If there is an internal short in the box, the fuse will blow, the car will stop, and that will be that. BUT, if the line that is feeding that box shorts out against the firewall then, absent the master circuit breaker, the battery will give all the amps it has (and remember that is hundreds of amps) and I will have a big mess. The same is true for the ten gauge wire running eventually to the fuse box. There is never an occasion that I want more than 50 amps coming out of my battery (the starter solenoid feed to the starter motor doesn't count). That's why the master circuit breaker protects everything except the starter solenoid feed to the starter motor. The added resistance of the circuit breaker itself is negligible. Now, I'm not so concerned about my alternator feeding a massive short because it can only muster 60 amps anyway. And, truth be told, most of the car wiring could handle 60 amps anyway. Remember, what a wire can handle is a function of its gauge and its length. Most of the wiring in a Cobra is pretty short (except the stuff running to the back of the car). So, for me, it's the battery I have to watch out for, and that's what the master circuit breaker does. Here's a nice little chart that shows you just how much some of our short, skinny wires can actually handle. And I'm not completely sure what Rick's set up is, so I'll let him describe it again.

http://www.clubcobra.com/photopost/d...wirelength.jpg

Awesome post Patrick I joke about you being the Guru, but you really are impressive!
So the fusible link wire is an excellent idea then for the exact reason you are saying protecting the MSD POS feed wire!!! In my car, that POS MSD wire cannot be longer than 5 feet from the box(under the glove comp) to the solenoid on the fire wall. Per your chart it should be good for 100 amps, that is awesome.
Thank you.
Just a thought... if you used just an inline fuse instead of the fusible link wire, it would be a lot easier to change out instead of being stuck on the side of the road. Also, your CB is the auto resetting type so if the scenario happen where the wire shorted out on the firewall, would it not keep on smoking and shorting due to the CB resetting itself?