Alternator Upgrade?

[Colbym]

Hello fellow mopar buffs,

I have a 1974 Plymouth Roadrunner which I got about 5 years ago and have been working on and enjoying since. I’ve come to an issue recently of not having a powerful enough amp output from my stock alternator. It’s rated at 100 amps, but I have an electric fan I installed with my new radiator recently that draws a ton of power and it won’t allow it to keep my battery charged. I’ve looked at some solutions involving getting some higher output alternators, but believe I will have clearance issues, I’m already maxed out on space with what I currently have. I do have AC in he car. Does anyone have any suggestions or have found a solution/part that will get me over this hump? Thanks in advance.

 

[747mopar]

Looks like there's tons of adjustment left in that alternator bracket, would longer belts allowing the alternator to be swung out help? If you don't mind a little work modern alternators are much more compact. Check out Summit and Mancini. I'm running a Denso, big alt in a small package.

 

[MoparLeo]

aboard. Remember that if you increase the load on the electrical system wiring, there can be consequences. The wiring is over 40 years old and wasn't designed for high out put stereos, electric fans, etc...Some precautions should be taken. Please read these articles completely a couple of times. You will not be sorry. Here is the info that you need.:
https://www.allpar.com/history/mopar/electrical.html

https://www.allpar.com/history/mopar/electrical2.html
http://www.madelectrical.com/electricaltech/amp-gauges.shtml
https://www.hotrod.com/articles/mopp-0808-fixing-dim-or-blinking-headlights/

 

[multimopes]

Welcome aboard Colbym. You have almost the exact car as me. Very Nice. I have a similar problem as you. I put a brand new 95 amp Power Master alternator in mine and it helped but was not the cure I sought. I have (2) electric fans and although at idle, I still get about 13 volts but when the second kicks in. voltage drops to around 11 volts. (No Good) If I step a little on the gas, the increased rpm's boost the voltage back up. I posted this problem here a few years back. I was suggested to put a smaller pulley on the alt, no soap, they don't make one. The answer is what was suggested above with a new smaller but more powerful Denso or similar. Most have the newer multigroove pulley so that would need changing unless I find an application that already has the v type pulley; ain't found it yet! The other part of the equation is the limited charge rate of factory regulators. Some of the newer types have a built in regulator which would solve that issue at the same time. Cost is another issue as well as time. Good luck and again welcome aboard to the absolute best Mopar site!
PS - please post up some more pictures of your beautiful ride and keep us posted on your progress!

 

[65RoadRacer]

Tuff Stuff and PowerMaster have 170 and I think higher amp alternators (1-wire) and Flaming River has a 240amp alternator (also 1-wire). I'm currently on a 100amp 1-wire and I know it's not enough, but it does keep the battery charged. The new engine has a 170 amp alternator. I think PowerMaster is doing a 240 amp unit now.

 

[Nacho-RT74]

Some notes:
There is not a chance a stock alt in old casing will give you 100 amps, unless stator has being modified! The bigger of those stock units could give you maybe 55 amps, which it means 25 to 30 amps iddling

That pulley is already the small one

Tuff stuff sells 100 amps ( and more ) unit on same old casing if you don't care to invest around $200. You don't need to get one wire alts just because everybody says it, stock replacement 3 wires from TS are quite enough ( I'm pointing out to that one when I get the money ). There is not a real improvement on one wire vs three wires, aside just for those who wants less wiress around.

You can also get 78 amps alts used on mid 80s Mopar on the cheap ( $40-60 ) which will give you around 45 amps at iddle and uses to be quite enough with just ocassional discharge readings at nights depending on blower speed, halogen lights and if geared while on a traffic light and raining, hence the wipers on ( the discharge readings will decrease around 80% with a regular use ). These units are a hair wider so, you could get a bit bigger belts to save the back of alt to meet the block, and also trim a bit the rear spacer.

BTW, must I say BEING THERE DONE THAT? My car is/was a driver living in a tropical country where AC uses to be a must

And run a bulkhead bypass/parallel wire AT LEAST between alt stud and black end of amm stud?

For more, here:

http://www.dodgecharger.com/forum/index.php/topic,33574.0/all.html

maybe I dunno what I'm talking about, just saying

 

[747mopar]

Some notes:
There is not a chance a stock alt in old casing will give you 100 amps, unless stator has being modified! The bigger of those stock units could give you maybe 55 amps, which it means 25 to 30 amps iddling

That pulley is already the small one

Tuff stuff sells 100 amps ( and more ) unit on same old casing if you don't care to invest around $200. You don't need to get one wire alts just because everybody says it, stock replacement 3 wires from TS are quite enough ( I'm pointing out to that one when I get the money ). There is not a real improvement on one wire vs three wires, aside just for those who wants less wiress around.

You can also get 78 amps alts used on mid 80s Mopar on the cheap ( $40-60 ) which will give you around 45 amps at iddle and uses to be quite enough with just ocassional discharge readings at nights depending on blower speed, halogen lights and if geared while on a trafficking light and raining, hence the wipers on ( the discharge readings will decrease around 80% with a regular use ). These units are a hair wider so, you could get a bit bigger belts to save the back of alt to meet the block, and also trim a bit the rear spacer.

BTW, must I say BEING THERE DONE THAT? My car is/was a driver living in a tropical country where AC uses to be a must

And run a bulkhead bypass/parallel wire AT LEAST between alt stud and black end of amm stud?

For more, here:

http://www.dodgecharger.com/forum/index.php/topic,33574.0/all.html

maybe I dunno what I'm talking about, just saying

I think we all know that you do know what your talking about lol. I've ran a few of the Tuff alternators and had nothing but good luck with them but yes they aren't cheap.

I'll admit I love 1 wire alternators for the reason you mentioned (cleaning things up under the hood) but if someone isn't going to put in the effort to rewire it then don't bother using one.

 

[65RoadRacer]

I'll admit I love 1 wire alternators for the reason you mentioned (cleaning things up under the hood) but if someone isn't going to put in the effort to rewire it then don't bother using one.

Can you explain what you mean about putting in the effort to rewire it?

 

[747mopar]

Can you explain what you mean about putting in the effort to rewire it?

What's the point in a 1 wire if you leave all of the unused wires, voltage regulator, etc... I guess dewire would have been a more accurate choice of wording lol.

 

[Nacho-RT74]

more than rewire it is clean up the excess of wires and remove regulator. There is not sense on use 1 wire alts keeping the stock reg and plugs floating all around.

Some alts like stock look so called "one wire alts" are nohing more than the SAME STOCK LOOK ALT with a MOUNTED ON REG which are activated by the stator like a trigger to make them work as soon engine begins to spin. Original reg is triggered on from ign key

Some other ONE WIRE ALT are simply similar to AC Delco alts, trully one wire alts.

Since somebody already posted a MAD Electrical link ( which I hate ), you can check further on Their website they opinions about one wire vs 3 wire alts... well, of course that's talking about the ooooldiest 1 wire alts. Can't tell about newer ones.

 

[Nacho-RT74]

This is the mounted on regulator available to become a firewall regulator system on a "one wire alt"

And is the unit you can find on stock alts became on "One wire alts"

Two wires to still feed the brushes ( and one of them to alt post too ) from outside like factory did, one to stator lead ( inside the alt ) as labeled, and the other wire to chassis.

This system is designed to "dual field" alts

 

[65RoadRacer]

What's the point in a 1 wire if you leave all of the unused wires, voltage regulator, etc... I guess dewire would have been a more accurate choice of wording lol.

Well, of course. That would stand within reason to remove the voltage regulator on the firewall and the associated wires. I was asking because someone once told me that a one-wire alternator won't work on a Mopar. I found that to be rather absurd... the single wire goes to the battery, which has no idea what type of car it's in. lol
I've had a one-wire alternator for four years on my car... never a problem.

 

[65RoadRacer]

Since somebody already posted a MAD Electrical link ( which I hate ), you can check further on Their website they opinions about one wire vs 3 wire alts... well, of course that's talking about the ooooldiest 1 wire alts. Can't tell about newer ones.

The early one-wire alternators did have some issues, they wouldn't charge at start up or at idle, but after talking with reps from Power Master, Tuff Stuff, and Flaming River (all of whom have one-wire alternators specifically for Mopars) they have all stated that their alternators excite as soon as it starts rotating, meaning there's no lag and you're putting out a charge at idle. In a couple of them, the charge at idle is rather significant with a higher-output like the 140-170 amp. I can't recall what the output is, but it's sufficient.

At idle, my voltage gauge reads 14+ volts, so it's definitely getting a charge. Once the temperature climbs and the electric fan kicks on, it does drop to about 13.

 

[Colbym]

Thank you everyone for all of yall's advise. Iv'e looked over all the resources posted and decided to upgrade to the one wire 130 amp tuff stuff alternator. (Great part and customer service)

I opted for this over power master since no mounting bracket modifications were needed when installing on an engine with a/c. Ended up rewiring everything on the alt to 4 gauge wire (7' positive to battery & 4' ground to block) as well as eliminating all old wiring for the external voltage regulator and ammeter. Also shortened and upgraded ground wire from block to battery with 4 gauge wire and added a voltmeter. All this being said, I'm still having issues with my car when the electric fan kicks on. In idle with battery connected I have 14.6 amps at the battery and 14.8 at my alt. When the fan kicks on it drops to 12.4 at the battery and 12.5 at the alt. If I also add my headlights to that it will then drop to 11.9 amps (not good). So needless to say after a good bit of time and money spent on this project I'm back to square one. I think I did a pretty thorough job of updating all wiring involved, and cant see why this new part wouldn't do the trick.

Anything I missing or any suggestions? Higher amp alternator? Also have had to replace the starting relay twice in the last 6 months including after the new alt.

 

[Scott Bender]

I put a Tuffstuff 100 amp in my Bee it works good but it has a funny whine like a supercharger which I have mixed feelings about. When you blip the throttle you can hear it go wheeeer wheeeer... Yep you heard right wheeeer.

 

[snooprob]

Colbym what was the final fix for your charging system?

 

[RJRENTON]

A curiosity question.....
IF you think your original charging system is inadequate, why would you not consider retrofitting with what Mopar used for high electrical load applications? This would include police or fire vehicle vehicles....Mopar used an alternator by Leece-Neville which included the appropriate regulator and wiring. Everyone seems to instantly turn to Power master, or some other brand "one wire" system which usually requires an externally mounted regulator, then complain about mounting and performance problems with their selection.
BOB RENTON

 

[HawkRod]

Why not consider another alternative? Fix your cooling system.

Get a good radiator and proper fan shroud/ mechanical fan combination and ditch the electric fans. I run A/C on my 70 Road Runner with the stock fan and shroud and a 4 core radiator. Never a problem even in 95 degree stop and go weather with the A/C on.

Thee fan shroud is CRITICAL to ensuring the the car stays cool. Too many people throw a radiator in their car and forget about the shroud.

Yes, you can modify your alternator and your entire electrical system - I also did on my 70. BUT, make sure you understand what you are doing. Throwing a big amp alternator in without addressing our wiring is a great way to potentially burn down your car. I'm not trying to be dramatic, but the old wiring (especially the poor connectors at the bulkhead) can barely handle 35 amps.

Good luck whatever you decide.

Hawk

 

[Nacho-RT74]

Yes, you can modify your alternator and your entire electrical system - I also did on my 70. BUT, make sure you understand what you are doing. Throwing a big amp alternator in without addressing our wiring is a great way to potentially burn down your car. I'm not trying to be dramatic, but the old wiring (especially the poor connectors at the bulkhead) can barely handle 35 amps.

This is partially true! The load required by the car won't change with a new alternator. If your car sucks let's say 35 amps, will suck the same 35 amps with a 35, 60 or 100 amps. The deal is when the alternator is not providing the car needs, the batt will provide that, and revving up, the alt will provide the car needs PLUS the batt recharge process. This mean your alt will provide 35 amps Plus 10, 20 or 30 amps depending on the batt charge level and alt capacity. This was the moment when the bulkhead came out weak, specially on black wire terminals at bulkhead.

Next miskate was add accesories on batt post, adding more loads what will run throught bulkhead and ammeter like alternator was charging the batt constantly. Accesories never had to be added to batt post but to alt post, or a junction between bulkhead/amm and alternator. So after 50 years of these mistakes, is a miracle some cars are still alive!

If you get an alt able to feed all the car needs, the battery will barelly supply loads, so the alternator load will remain steady at the same car demand, meaning that EVEN THE WEAK BULKHEAD TERMINALS could hold the load on a basic equipmed car. So, yes, wiring and terninals must be addressed based on car needs ( considering stock and new accesories ) or, after all these years of abuse and bad use at least mantenience, BUT first the alt must be upgraded to be able to suply all the power at any speed, keeping the batt out of the game most of the time as posible.

Wiring and terminals must be calculated based on the car needs more than the alternator and battery load levels. And one example for this is, when you have a battery with a 150 amps cranking power. This batt will feed the same your dome light barelly sucking 1 amp, than your starter motor sucking 100 amps. Wiring gauges are not related to the batt but to the devices keeping the same source.

 

[Nacho-RT74]

A curiosity question.....
IF you think your original charging system is inadequate, why would you not consider retrofitting with what Mopar used for high electrical load applications? This would include police or fire vehicle vehicles....Mopar used an alternator by Leece-Neville which included the appropriate regulator and wiring. Everyone seems to instantly turn to Power master, or some other brand "one wire" system which usually requires an externally mounted regulator, then complain about mounting and performance problems with their selection.
BOB RENTON

That could be a good idea if they were available growing out from trees LOL. BUT even finding the propper Leece Neville alt/reg set, brackets are not around that easy, sooooo, keeping what you got on car, changing to a upgraded unit on same case is normally the way to go.

Or buying aftermarket kits like some sellers offer based on some newer alts.