Simple Bulkhead Bypass

[Sir Dodge alot]

Button up the dash knowing you have made your car that much more reliable and fun to drive.
Oh and dont forget to connect the battery,LOL!!
Cheers and let the questions fly!!
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Depending on your car,you may have to pull the gauge cluster out for this next step.
Refer to your car's Shop manual for cluster removal.
Or be adventurous and work upside down if you have small hands.

Connect the wire to the RED terminal of the ammeter gauge.
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Hello there Sir, I have a question if I may ask it.

Would this bukhead bypass ammeter connection modification still work on cars that have the ammeter built into the fuel gauge?

There are three wires coming out of the gauge spade terminals.
light BLUE, BLACK, RED.

Is connecting an additional wire to the RED spade terminals all that's needed?

Vehicle: 1964 Dodge custom 880

Much thanks.

 

[cbarge]

Hello there Sir, I have a question if I may ask it.

Would this bukhead bypass ammeter connection modification still work on cars that have the ammeter built into the fuel gauge?

There are three wires coming out of the gauge spade terminals.
light BLUE, BLACK, RED.

Is connecting an additional wire to the RED spade terminals all that's needed?

Vehicle: 1964 Dodge custom 880

Much thanks.

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According to the schematics you posted, the ammeter is separate from fuel guage.
Do not confuse the integrated voltage limiter with the ammeter. Two totally different things.
Just an additional wire is needed to the R6A terminal connect through firewall to battery stud of starter relay with fusible link at relay.
Hope this helps as I am not totally familiar with Mopar electricals prior yo 1965.

 

[Sir Dodge alot]

According to the schematics you posted, the ammeter is separate from fuel guage.
Do not confuse the integrated voltage limiter with the ammeter. Two totally different things.
Just an additional wire is needed to the R6A terminal connect through firewall to battery stud of starter relay with fusible link at relay.
Hope this helps as I am not totally familiar with Mopar electricals prior yo 1965.

Thank you very much sir, that gives me some food for thought on tackling this job at hand.

I'll referance the wires under the dash and refer to the FSM.

 

[Sir Dodge alot]

Doe! it turns out the ammeter IS the alternator gauge, and i chickened out at the last second to apply the bulkhead bypass, i didn't have 10 gauge wire. (Only 14 to 18 gauge) but soon as i do get 10 gauge wire, this bulkhead bypass will be top on the priority list. Also, fantastic writeup Cbarge as expected from you and the past underhood ammeter bypass thread. followed that to the T and got slightly brighter headlights!
unless there is a whole lot of the placebo thing going on!
One thing for sure is that the engine does sound smoother at idle and at cruise.

 

[Gerald Morris]

Doe! it turns out the ammeter IS the alternator gauge, and i chickened out at the last second to apply the bulkhead bypass, i didn't have 10 gauge wire. (Only 14 to 18 gauge) but soon as i do get 10 gauge wire, this bulkhead bypass will be top on the priority list. Also, fantastic writeup Cbarge as expected from you and the past underhood ammeter bypass thread. followed that to the T and got slightly brighter headlights!
unless there is a whole lot of the placebo thing going on!
One thing for sure is that the engine does sound smoother at idle and at cruise.

If you go with 8 gauge, you can increase your alternator ampacity to a nice full 60 amperes. I did, then used #6 when I went to a 95 amp alternator. Be SURE you make ALL the power conductors the same size when you go even to #10 wire. Most of the old boats had #12 from the alternator, with 10 gauge from the battery, and a 14 gauge fusible link protecting that. Be sure to make your fusible links 2 even numbered iterations smaller than the conductor. To wit: #14 for #10 conductors, or #12 for #8 et cetera.....

 

[Sir Dodge alot]

If you go with 8 gauge, you can increase your alternator ampacity to a nice full 60 amperes. I did, then used #6 when I went to a 95 amp alternator. Be SURE you make ALL the power conductors the same size when you go even to #10 wire. Most of the old boats had #12 from the alternator, with 10 gauge from the battery, and a 14 gauge fusible link protecting that. Be sure to make your fusible links 2 even numbered iterations smaller than the conductor. To wit: #14 for #10 conductors, or #12 for #8 et cetera.....

Much appreciated Sir! for the valuable information. Still learning the ropes on chrysler electronics/wiring.

I believe I used 14 gauge on the alternator to starter relay stud, with 18 gauge as my fusible link.

But seeing your write up makes me think i should go back in and update the Underhood ammeter bypass wiring.

Thank you again!

 

[Gerald Morris]

Just checked my notes AND my current circuiting under my hood! I actually am using #8 AWG welders wire for my power conductors from both the alternator and the battery. I run the charging lead around the FRONT of the compartment, along the bottom front of the radiator directly to the battery, with the #12 fusible link for the last 6 inches. I then run another fusible link of that length and size to the starter relay. From there, I go with another #8 wire directly through a grommet in the firewall, and terminate this to BOTH of the lugged #12 AWG wires which formerly were on the ammeter. I disconnected all other power leads through the firewall.

Thus, both main power circuits under the dash start from the same node, the 8 gauge wire from the battery. The alternator goes directly to the battery first and stops there, save of course batteries act also as large resistors, and current sources when equipotent with the alternator. If lower in voltage, it charges.

I also run a fuse bus right off the battery to feed a few relays and an accessory circuit.

 

[Sir Dodge alot]

Just checked my notes AND my current circuiting under my hood! I actually am using #8 AWG welders wire for my power conductors from both the alternator and the battery. I run the charging lead around the FRONT of the compartment, along the bottom front of the radiator directly to the battery, with the #12 fusible link for the last 6 inches. I then run another fusible link of that length and size to the starter relay. From there, I go with another #8 wire directly through a grommet in the firewall, and terminate this to BOTH of the lugged #12 AWG wires which formerly were on the ammeter. I disconnected all other power leads through the firewall.

Thus, both main power circuits under the dash start from the same node, the 8 gauge wire from the battery. The alternator goes directly to the battery first and stops there, save of course batteries act also as large resistors, and current sources when equipotent with the alternator. If lower in voltage, it charges.

I also run a fuse bus right off the battery to feed a few relays and an accessory circuit.

From reading, it seems like you replace the factory wiring with heavier gauge wiring?

I suppose the next owner that buys the car may be confused to why the wiring schematic shows different wiring insulator colors than what is on the vehicle.

I'll take note of keeping track of what the wires are for and where they go to.

Thanks much for the "roadmap" I may take aswell!

 

[Gerald Morris]

If you want to run any modern accessories, it behooves you to increase the ampacity of the system. I run an electric pusher fan to keep that engine cool in the summer heat in urban traffic here, which these cars were NOT well equipped to handle even when they were made. Shrouds and clutch fans help only so much when stalling bumper to bumper for a half hour or more at a time. While I refuse to run air conditioners or high wattage audio systems, having some extra charging for my brats' digital toys et al helps too.

The matter of powering headlights also merits upsizing the power ampacity on these old rods. SHORT, high current conductors with relays switched by the old 16 AWG headlight harness provide power to either the original incandescent headlamps (MY preference) OR, as many folk want, modern headlights, which sometimes require higher current wiring. (I LOATHE THIS DANGEROUS **** and would love to see it BANNED from public thoroughfares, as it once WAS, when the D.O.T. had some authority. Blinding oncoming traffic or folks in front of you through their rear view mirrors should be prosecuted as attempted homicide at the least.)

Some of the issue regarding power conductors in a C body Mopar arises from whether one drives a collectors item or a working vehicle. I drive the latter, and prefer C body Mopars for their superb design, excellent handling, power and SIMPLICITY. Be sure of this: I DON'T advocate making anything on these excellent machines more complicated!

Corporate niggardliness combined with ignorance when determining the original wire sizes in these cars. If you prefer to keep your ride "original" for purist reasons, well and good, so long as you know the risks. But, if you want a usable vehicle, then by all means you should upgrade your wiring harness! Wire fires can ruin a car.

 

[Sir Dodge alot]

I've heard stories of the shoddy ammeter wiring burning a car to the ground, guess it all comes down to keeping the car "original" (and the wiring) and risk having the car smoldering. Or modify the stock wiring and have peace of mind eh?

I'll admit I was strongly considering LED headlights for better visability but it just wouldn't look right, and the wiring modifications seem a bit overwhelming to me.
(Attaching splices, relays and what not)

 

[Gerald Morris]

I took a pic of my current power setup for you:

The 8 gauge welding wire is sheathed in 1/4" split loom flex. running under the radiator and comes up to the battery. I use a split bolt to fasten that to the #12 fusible link attached to the + stud on the battery marine terminal. I use ring terminals on the 3 fusible links here, one for the alternator, one to the starter relay, and the third to the auxiliary fuse bus I put to the right of the battery.

I'll run the headlight relays from that fuse bus later this year, when time and circumstance permit. Today, I upgraded my cooling fan for the summer. I'll post a thread on that later this evening, hopefully.

The alternator is a 95A PowerMaster which I got from Speedway on a GOOD sale. It's been very reliable so far....

 

[Sir Dodge alot]

I'll consider getting a beefier alternator if my stock 60Amp alt is Insufficient for some odd reason.

Cooling fan upgrade eh? Looking forward to it!

 

[cbarge]

I'll consider getting a beefier alternator if my stock 60Amp alt is Insufficient for some odd reason.

Cooling fan upgrade eh? Looking forward to it!

I also run the 90 amp Powermaster "Roundback" alternator. I doubled up on the wiring and wrapped it to look "stock"

 

[Gerald Morris]

I also run the 90 amp Powermaster "Roundback" alternator. I doubled up on the wiring and wrapped it to look "stock"

VERY NICE LOOKING compartment there! I like the old style battery. Is that a case or one of those retro looking batteries?

The new FFD fan certainly BLASTS, and I've reached saturation on moving air through the radiator now. The NEXT physical issue to address is the COOLANT FLOW RATE! I installed a good old non-AC HP water pump w the 8 vane 4.375" impeller, which DOES move more coolant at lower engine RPM, resulting in quick drops in coolant temperature. But when idling in urban traffic, while this one does BETTER than the cheap Gates pump built on OEM AC water pump specs, "BETTER" still leaves much to be desired.

So, I'll weigh carefully this Spring whether to go with total electric engine cooling or not. I sure like the possibility of running a coolant pump independent of engine rotation, but will sure want to upgrade the alternator yet AGAIN.

I love this Powermaster 95A unit, but likely will have to go to a 130A alternator if I step up to total electric cooling. I might hold off until the 400 gets built. We're most probably going to do that this summer.

I can get the headlight relays in this Spring though.... I like the better performance I got from my 50+ yr old headlamps with the harness I had in Mathilda. That harness remains intact so it just needs to be ported. Short 10 gauge conductors sure do better at lighting those lovely old incandescent lamps, with the 16 gauge harness being relegated to switching the Bosch SSRs. I'll never use LEDs for the main headlamps.

 

[cbarge]

Is that a case or one of those retro looking batteries?

Battery topper..50 bux.

 

[Gerald Morris]

The car looks damned good. I'm researching Meziere's offerings in electric pumps. They don't draw as much current as I thought, which is good! For now, I'm most likely to put a smaller pulley on the pump to turn it a little faster when idling. One can blow a hurricane through the radiator, but unless that coolant MOVES, its for naught. I've looked at Flowkooler's stuff also, especially if one wants a high end mech pump.

 

[Ross Wooldridge]

Don't move the coolant TOO fast Gerald - part of what cools the coolant is the amount of time spent in the radiator. Gotta find the balance. Too fast, and it doesn't get cooled. Too long, and it doesn't circulate quickly enough INTO the engine after being cooled...

That's why the AC water pumps only had 6 vanes instead of 8 like the non-AC water pumps - so as to maximize time spent in the radiator.

 

[Gerald Morris]

Don't move the coolant TOO fast Gerald - part of what cools the coolant is the amount of time spent in the radiator. Gotta find the balance. Too fast, and it doesn't get cooled. Too long, and it doesn't circulate quickly enough INTO the engine after being cooled...

That's why the AC water pumps only had 6 vanes instead of 8 like the non-AC water pumps - so as to maximize time spent in the radiator.

WELL aware of the possibility of moving the coolant too fast. One has but to pull the thermostat to achieve that with even the modest capacity of what I currently run. (Didn't happen with the Gates pump though.)

Having a good temperature gauge and an IR thermometer helps when experimenting with this issue. No 2 ways about the current setup: flow needs to INCREASE for temperature to DECREASE. Where the inflection point will be, I have yet to determine. Have you seen that old thread about pumps and flow rates? Its pretty illuminating, on THAT issue.

 

[HOT FURY]

This is great Leaburn, and thank you!! And for fun, I responded last night immediately upon you saying for us NOT to post until you were done just to piss you off!! LOL!!

Question - while your modification removes a very large amount of the constant high amperage power running through the bulkhead from the engine bay to the ammeter, there are a few high power things that run BACK to the engine bay THROUGH the nasty old bulkhead AFTER the ammeter and the welded splice in the dash harness (headlights, AC compressor, etc etc). To make this a true Bulkhead Bypass, can these return power feeds not be run through the firewall as well avoiding the pesky spade connectors in the bulkhead? Maybe using insulated terminal blocks for serviceability? (see below)... would that not reduce the bulkhead overload issue that can exist with those circuits by doing that as well?

Observation: My 66 Monaco has the police style power delivery system which used a bulkhead bypass almost exactly as described, but rather than running an unbroken wire from the starter relay through the firewall to the ammeter, it runs it to a nice insulated terminal block bolted to the firewall, and then through the firewall in its own special hole to the ammeter. In this case the starter relay is on the firewall (rather than the inner fender like your car), and the factory used a fusible link (red with a white stripe) run directly from the relay terminal to the insulated terminal block (upper left just below the hood spring bar), then a new red ammeter feed wire going down to a hole in the firewall with a grommet (you can't see the hole, but you can see the feed wire - it's the vertical red wire). As you stated, they also retain the fusible link from the bulkhead, so you can see the two yellow fusible link plastic identifiers on the starter relay bolt. This allows for some serviceability - see the photo below. In my car this is where the voltage regulator would be, but in some police cases (and I've seen this on Imperials too), the voltage regulator is mounted on a special bracket on the inner fender, and the wiring harness is modified with a jumper wire from an additional terminal block from the regular harness to the regulator on the inner fender. You can see the second terminal block below the red and white fusible link wire.

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I have a stupid question, I'm trying to fix some of the shortcomings of the electrical circuits in the factory setup of my 66 sport fury but not well versed in electrical. I can do basics and follow wiring instructions well but some terminology gets complicated without visuals. I recently upgraded the headlights with a new harness incorporating relays to reduce the load on the dash switch and added the ammeter bypass link from the alternator to the starter relay. What will this modification do to help avoid any electrical issues? I can mount a small insulated terminal block on the firewall to wire just like your factory setup since I like the starter relay mounted there rather than the inner fender area the other post had.

I am also getting ready to add a better stereo system(nothing too crazy but higher power speakers and a small amp) and going with a fuel injection system. Will this upgrade be a necessary update to avoid issues since I will be direct wiring the amp to the battery through a busbar I installed? Any input on alternator upgrade and how any of the mods I already made will need to be altered with an upgrade? (thinking around 90-100 amp since I don't plan on adding any more load than just mentioned)

 

[cbarge]

I have a stupid question, I'm trying to fix some of the shortcomings of the electrical circuits in the factory setup of my 66 sport fury but not well versed in electrical. I can do basics and follow wiring instructions well but some terminology gets complicated without visuals. I recently upgraded the headlights with a new harness incorporating relays to reduce the load on the dash switch and added the ammeter bypass link from the alternator to the starter relay. What will this modification do to help avoid any electrical issues? I can mount a small insulated terminal block on the firewall to wire just like your factory setup since I like the starter relay mounted there rather than the inner fender area the other post had.

I am also getting ready to add a better stereo system(nothing too crazy but higher power speakers and a small amp) and going with a fuel injection system. Will this upgrade be a necessary update to avoid issues since I will be direct wiring the amp to the battery through a busbar I installed? Any input on alternator upgrade and how any of the mods I already made will need to be altered with an upgrade? (thinking around 90-100 amp since I don't plan on adding any more load than just mentioned)

The bypass takes 50% of the load away from the ammeter gauge, and eliminates any electrical breakdowns should the ammeter shorts out.
All of the car's current flows through the ammeter. No ammeter, no working car, got it?
I am using the Powermaster 90 amp alternator with the underhood ammeter bypass using a heavy gauge wire 8 or 10 if i can remember.
With EFI follow the instructions and if possible use relays for everything.
Your stereo equipment being fed from the battery should be fine. Use heavy gauge wire and appropiate fuses for the amp output. Ultimately, depending on the stereo, having its own deep cycle battery would be best separate from the car battery.
Hope this helps.