MSD impact on charging system question

[BananaDan]

I have noticed that since my MSD install, my ammeter bounces with a steady rhythm from 0 to +10 (approx) when at idle.  Before when I was on the orange box the needle would stay pretty steady.  Oh, every inch of wiring in my car is new (Evans harnesses and M&H dash harness).

Is this to be expected?

[myk]

I'm running a voltmeter along with my MSD, but my gauge has always been steady.  I don't see why the MSD would cause such a behavior with your ammeter.  Have you placed a voltmeter across your charging system while the car is running to verify the drops in power?

[BananaDan]

No, I haven't checked that.  It will be some time until I can as she's buttoned up for the winter.  I am pulling my cluster shortly to send out and I'm planning on replacing the ammeter with a voltmeter.  However I just want to know if others have experienced this or if it is a sign that there's an issue somewhere.  When the engine is under load and at higher-than-idle RPMs, the ammeter reads steady and usually at or close to 0.

[firefighter3931]

Dan, what do you have the idle speed set at ? Mopar alternators are notorious for low amperage output at idle engine speeds. 

The fact that the ammeter reading flattens out at higher engine speeds where amperage output increases with RPM is a good indicator that the charging system might be overtaxed. 


Ron

[BananaDan]

Dan, what do you have the idle speed set at ? Mopar alternators are notorious for low amperage output at idle engine speeds. 

The fact that the ammeter reading flattens out at higher engine speeds where amperage output increases with RPM is a good indicator that the charging system might be overtaxed. 


Ron

Thanks Ron, that's what I was afraid of.  According to my timing light when I did my advance curve (before MSD install) she idles at 1,100 RPM.  The ammeter didn't do this prior to the MSD install so I was curious if the MSD places a higher load and is taxing the charging system at idle.  Sounds like that's what you're saying?  I've read about both alternator upgrades (higher amperage) or just changing to a smaller pulley on the alt.  Which do you recommend?  I have a modern alternator (AC Delco) replacement but I believe it is stock specs, or whichever they offer as the OEM replacement (not a crazy modern high amperage model).  The mechanic that I used to do my post-body work assembly put it in (he's an AC Delco shop) and I failed to get the model number of what he bought, but I know he just went with their OEM version and not an upgraded model. 

[firefighter3931]

Dan, if it's a stock replacement alternator then the problem most likely lies there. Yep, the MSD box does suck up a bit more juice vs a conventional ignition. 

I use a Tuff Stuff Mopar style alternator on mine and it works great. The one I'm using is a 100 amp model but I have more accessories on mine than you do ; big electric fuel pump and electric fan in addition to the MSD box. These alternators have increased output at idle as well as at higher engine speeds. 

The 60 amp alternator would be sufficient for your needs, inmho 

**These are not internally regulated or GM style alternators commonly referred to as "one wire"....they are a Mopar style with external regulator and use stock engine bay wiring (dual field with external regulator)

http://www.tuffstuffperformance.com/index.cfm/page/ptype=product/product_id=8127/category_id=175/mode=prod/prd8127.htm

Summit has them : http://www.summitracing.com/int/parts/tff-8509sp

Hope that helps ?



Ron

[BananaDan]

Thanks Ron.  I took a quick look at Rock Auto and it seems that AC Delco only makes 60A alternators (nothing smaller I mean) as their OEM replacements.  That would mean that if I had to guess, I'm already at a 60A alternator.  Are you saying that the Tuff Stuff, although also 60A, does a better job and puts out more amperage at idle and will help me?  I do see that it's 3x the price of the AC Delco OEM model on Rock Auto so there's something going on under the hood of the Tuff Stuff.   

If so then I'm good and that's what I'll do.  I agree that I am good at a 60A today, as my electrical accessories are all stock except for MSD and a SecretAudio stereo.  However, I do have eventual plans to add an amp to the stereo to drive my 6x9's and add a sub.  I would also like to upgrade to HID lights with relays that I've read about one day.  Considering those future upgrades, should I go with the 100A alternator, or would 60A still be enough?  I have no plans for electric fuel pumps or fans.

Thanks!

[firefighter3931]

With the additional electrical load you're planning for the future I would strongly consider the 100 amp unit and be done with it. 

On mine....I installed an extra 8G wire from the alternator stud to the starter relay stud with an inline fusible link to protect the wiring harness and it's been working fine for several years now. 


Ron

[BananaDan]

That's what I was thinking.  Something like this?  Which gauge fusible link would I use as this URL shows a smaller gauge fusible link being used with a larger gauge wire?

http://www.madelectrical.com/catalog/fusible-link.shtml

I have also read about people sending a dedicated wire from the alt stud straight to the battery (pos terminal I guess)?  Should I do that as well, or is that unnecessary?

This would be the alt to use, right?

http://www.tuffstuffperformance.com/index.cfm/page/ptype=product/product_id=8103/category_id=175/mode=prod/prd8103.htm

[firefighter3931]

Dan, I used a 12g fusible link with the 8g jumper wire. No single wire to the battery if you're connecting to  the starter relay stud. 

Yes on the alternator....the one you linked is for stock wiring and external voltage regulator. 


Ron

[BananaDan]

Thanks again Ron!   

[Nacho-RT74]

mmm, lot to say about this... as you know, I'm not agree with all what MADelectrical website states

[BananaDan]

Any more of that info you refer to that I should consider Nacho?  I only used that site for the pictures.  They were the first Google search result.  I wasn't using them for any info/advice.

[Pete in NH]

Hi,

I don't care for the MAD modification as they have written it up. Too many slices that are not needed and they still run a loop through the firewall. One part I really don't like is drilling out the original bulk head connector, which ruins the connector should anyone want to revert to the original wiring in the future.

Ron outlined what you need to do with a new 8 gauge wire and 12 gauge fusible link between the alternator output stud and battery post on the starter relay. You will also need to add another 8 or 10 gauge wire from the battery stud on the starter relay through the firewall to the black wire that used to go to the ammeter. This wire should be fused with either a 16 gauge fusible link or I prefer a 50 amp Maxi-Fuse.

[BananaDan]

Thanks Pete. As I said above, I just used the MAD page because I was doing a search on fusible links to make sure I bought the right size.  I have no intent to follow their guidance .  Heck, I never even read any of the content on the site.  I just found that individual page in a Google search looking for fusible links to make sure I purchased the right one.

On your advice for the extra run through the firewall to the black wire that comes out of ammeter, what function does that perform?  I will be removing my ammeter in this winter project and replacing it with a voltmeter so I plan to splice the red and black ammeter wires together.  That said, do I still run another wire through the firewall and join it with the red and black wire splice?

[myk]

It's all a matter of preference IMO; there are several ways to increase the pathetic electrical system from the factory.  Theres nothing wrong with MAD electrical's method if all you're going for is functionality and reliability and aren't concerned with the factory stuff...

[Dino]

Dan the 8 gauge wire running through the firewall replaces the stock fusible link going through the bulkhead connector.  The link is the only thing protecting the wiring inside the car should something go wrong.  By running the 8 ga from the starter relay stud to the black wire going to the splice behind the dash you bypass the bulkhead connector.  A fuse on this 8 ga wire protects everything behind the firewall.  I have this exact same thing, thanks to Pete, and run the wire through a 50 amp maxi fuse. I went a bit further on my car and removed the red and black wire from the ammeter completely.  I run the 8 ga wire directly to the main splice.  Don't do this if ever you want to revert it back to stock though.

[1974dodgecharger]

Mad setup works for me...I like how they tie together the neg and pos side together and come out the bulkhead tie it together with a fuesable 14guage setup it makes it double duty.  I modded mine diff though my alt goes straight to battery and with 1970 voltage regulator have a more consistent power pre 70 sucks even with 180 amp idle amd 320 max output.

[Pete in NH]

Dino covered the topic very well and I'll only add that the idea is to get those bulk head connector pins out of the way, since they are a major problem area, especially after 40+ years of corrosion that may have set in.

[BananaDan]

I do like to keep a stock appearance however, and all of my wiring is brand new.   

[Dino]

Unless there's a hole in the firewall already to sneak an 8 gauge wire through it won't look stock.  I have mine running through the tach hole which is going to be a problem when I install the tach.   

With an upgraded alternator my only concern would be the load on the fusible link wiring but if you don't have a ton of stuff running it should be alright.  The black and red wires are 12 gauge so they can take a decent load, but the Packard terminals are the weaker link.  Maybe you can just get new ones just fur the fusible link and the red wire going to the ammeter if yours are old?  You can make sure they are nice and tight by gently closing the female end but be careful not to push the wire out the other side, ask me how I know that can happen.    

Use plenty dielectric grease as well, the last think you need here is arcing.

Once you have everything installed you can test it by running all the electrical at once for a while and then checking the temperature on the Packard terminals.  My original bulkhead connector was melting away around this terminal and everything on the car was stock, that's pretty scary.

[Nacho-RT74]

sorry I have being very busy, and tired.

The main deal I don't like MADelectrical statements is they say the main buss is being moved from inside the cab to the starter stud... which is not totally true. Even it gets a big splice point there, there is not a way to move the main "buss" from inside the cab without heavier mods. The main buss is still the welded splice into the cab between alt and ammeter. After read that, I definitelly considered that website as something to be read with care

and... if you get a balanced charging system, and propper upgrades, you don't need to get rid off the stock design. Of course as all of you know, I'm a stockish guy.

diff deal is if you don't like the stock design, or are unsure of conditions of your car electricity, or don't feel comfortably with it, mostly due unknoledgement.

Electricity needs to be restored or rebuilt as we restore body and rebuild engines, but mostly of ppl don't take care correctly about this specific area