Slant Six Forum :: Relay conversion for top operation & electric choke Q

The switch that presently operates the top is a three position intermittent toggle. When it is centered nothing is energized, push it up to rase the lid and a full thirty amps flow down a # 12 wire yellow to the pump. release the switch and it returns to off, push it down and the lid goes down with 30 amps flowing down a brown #12 wire.

What I am going to do is replace the up contact with relay "A" yellow, and the down contact with relay "B" brown.

I will utilize the old existing toggle switch proudly mounted on the dash adjacent to the headlight switch to activate each relay as needed to either rase or lower the top. Anyone operating i the top will never know relays are doing the heavy lifting in place of having the 41 year old switch carry 30 amps. By doing this I will reduce the current draw through the old switch by huge amount, and won't need any fire permits for out side burning before lowering the top.

All that is simple. My concern was which circuit to tap into to feed the low draw side of this set up that was only energized when the ignition is on. I have decided that the same circuit the radio is feed from will do just fine where there is little draw, and not constant, rather a very low duty cycle.

I will keep the relays close to the amp gage feed to reduce the length of live conductor. The last thing this car needs is an extra 20 feet of continuous hot wire traveling to the rear of the car.

It is bad enough to have a hot conductor connected to the amp gage from the battery protected by a fusible link. What were the engineers thinking back then.

I agree with you that the stock wiring was not adequately protectedbut I suspect this might be true of many automotive designs

Only horrific if a MOPAR, or perhaps a few English marques... er, rather German & Indian now... spontaneously combust. All others ars just getting to the smelter ahead of their design life.

The 300 C is the best Chrysler ever built

Your friend may have a point with MOPAR's mid size junk, and the old K-Cars.

Dan,

You mentioned a ground side electric choke modulator. Do you have any part numbers

and see any reason it wouldn't work with a Holley electric choke?

Author:	Charrlie_S [ Thu Mar 27, 2008 6:01 am ]
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Quote: The switch that presently operates the top is a three position intermittent toggle. When it is centered nothing is energized, push it up to rase the lid and a full thirty amps flow down a # 12 wire yellow to the pump. release the switch and it returns to off, push it down and the lid goes down with 30 amps flowing down a brown #12 wire. What I am going to do is replace the up contact with relay "A" yellow, and the down contact with relay "B" brown. I will utilize the old existing toggle switch proudly mounted on the dash adjacent to the headlight switch to activate each relay as needed to either rase or lower the top. Anyone operating i the top will never know relays are doing the heavy lifting in place of having the 41 year old switch carry 30 amps. By doing this I will reduce the current draw through the old switch by huge amount, and won't need any fire permits for out side burning before lowering the top. All that is simple. My concern was which circuit to tap into to feed the low draw side of this set up that was only energized when the ignition is on. I have decided that the same circuit the radio is feed from will do just fine where there is little draw, and not constant, rather a very low duty cycle. That will work just fine. My only question is: why use a different 12 feed? Why not the original factory feed, it will work just fine, with the lower current draw. You will only be feeding the relay coils.

Author:	Sam Powell [ Thu Mar 27, 2008 6:22 am ]
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I would put the two relays near the pump motor. You will need to run one high current +12Batt wire to the power feeds to the relays, and ground the relays to the chassis where they are mounted. The yellow and brown wires that currently run from your switch to the pump will then be hooked to the relays as Dan describes in his post. The power for the pump now come from the relays, again wired as Dan says. You only need to run one new wire. The only question now is, where to get the 12V batt power. Yu can either fuse it seperately, and come off the hot plus side of the battery, or use the same fuse that already powers the top pump switch. Just run a heavy wire from the fuse box, back under the threshold to the new relays. A convenient place to get your underhood 12V power is the starter relay. There is a 12+ on one side of that. Just be sure to mount a fuse on the fender and fuse the line so you don;t burn your car to the ground if the wire under the threshold gets pinched and grounded.

Author:	wjajr [ Thu Mar 27, 2008 8:13 am ]
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Charrlie, I don't want to be able to operate the top with the ign. key in the off position. Sam, There is no fuse on this circuit, the power comes from the black side of the amp gage passes through a 30 amp circuit breaker integral with the top switch, where the power is fed to the pump. I will keep the relays close to the amp gage feed to reduce the length of live conductor. The last thing this car needs is an extra 20 feet of continuous hot wire traveling to the rear of the car. It is bad enough to have a hot conductor connected to the amp gage from the battery protected by a fusible link. What were the engineers thinking back then. The new cars all have fuse boxes under the hood so there is very little unprotected conductor to burn up. The fewer live conductors this car has when the ing. is off the better.

Author:	66aCUDA [ Thu Mar 27, 2008 8:38 am ]
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Im with you on long hot wires but why not mount the relays under the hood? I personally dread the bulkhead connector failure worse than the threshold. Just a thought. Frank

Author:	SlantSixDan [ Thu Mar 27, 2008 9:09 am ]
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Quote: I will keep the relays close to the amp gage feed to reduce the length of live conductor. The last thing this car needs is an extra 20 feet of continuous hot wire traveling to the rear of the car. Agreed. Good philosophy. And add an appropriately-rated fuse between the power takeoff and the relay #30. Quote: It is bad enough to have a hot conductor connected to the amp gage from the battery protected by a fusible link. What were the engineers thinking back then. They were thinking "minimally adequate protection against catastrophic short circuits at minimum possible cost".

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Author:	wjajr [ Thu Mar 27, 2008 6:10 pm ]
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I just replaced the bulkhead disconnect with a NOS unit. I have replaced all corroded connectors under the hood, and the dash, also many conductors that showed damage from over heating & hacking have been replaced. The only part of the harness that did not get new connectors was rear of the car, those just needed a little cleaning because they were not exposed to the weather. For the hard top crowd, convertibles on occasion become bath tubs. If the carpet & pad are not quickly removed to be dried, the car rusts. Everything in the cockpit rusts, and corrodes. There is a little confusion as to what a relay is. Think of it as a remote control slave. A light duty switch directs a small current to the relay activating an electromagnet which inturn closes or opens a larger set of contacts (the slave) that can handle a large load. Relays have two sides. Side "A" high amperage, and side "B" low amperage, or load. In the proposed modifications to the top pump circuit the old factory switch will power "B", the low side of the relays. The "A" high side will be feed from the amp meter as the factory built the car. The amperage passing through the old dash mounted switch will be minimal. The "A" side of the set up will have to carry up to 30 amps. Of the two electrical schematics I have on this car, neither one shows the top pump motor circuit. A previous owner had bypassed the amp gage, and bolted the red (feed from battery), red with tracer (top motor feed), and black conductor together, taped them up, and left them to dangle. I belive the factory had landed both the black & red w/tracer on the load side of the amp gage.

Author:	Sam Powell [ Fri Mar 28, 2008 6:12 am ]
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I see your point about having a hot wire running the length of the car, but if, as you say, you want it switched with the key, then it will only be hot while you are drivning the car. In which case, you have several hot wires running the length of the car anyway: your tail lights at night, the feed to the fuel gauge, and in my case, a fuel pump feed, and a battary cable since the battery is in the trunk. It sounds like you have a pretty good idea of how you want to do this now. It also sounds as if you are pretty well grounded in basic automotive wiring theory. I hope the discussion was of some value to you. I learned something. I agree with you that the stock wiring was not adequately protectedbut I suspect this might be true of many automotive designs, as you see the horrific sight of a car burning up once in awhile. Sam

Author:	wjajr [ Fri Mar 28, 2008 6:38 am ]
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I agree with you that the stock wiring was not adequately protectedbut I suspect this might be true of many automotive designs, as you see the horrific sight of a car burning up once in awhile. Only horrific if a MOPAR, or perhaps a few English marques... er, rather German & Indian now... spontaneously combust. All others ars just getting to the smelter ahead of their design life.

Author:	SlantSixDan [ Fri Mar 28, 2008 7:12 am ]
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Quote: I agree with you that the stock wiring was not adequately protectedbut I suspect this might be true of many automotive designs It's not just wiring, either. It's a proven, scientific fact that having a blue oval name badge anywhere on the vehicle greatly increases the likelihood of the vehicle catching on fire and burning down. Quote: Only horrific if a MOPAR, or perhaps a few English marques... er, rather German & Indian now... spontaneously combust. All others ars just getting to the smelter ahead of their design life. I would quote my automotive-writer friend had to say (accurately) about the current junk coming from Chrysler, but I might get run outta town for it. Aw, heck, I'm leaving town for Switzerland in a few hours anyhow, so here goes: "The best thing that can be said about current Chrysler products is that they can be recycled into better cars."

Author:	wjajr [ Fri Mar 28, 2008 7:36 am ]
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The 300 C is the best Chrysler ever built, additionally the proper wheels propel these buggies. Your friend may have a point with MOPAR's mid size junk, and the old K-Cars. hopefully the three headed dog will produce a few decent new products in the near future. I had planed on doing this (see link below) to my black 300C, http://coachbuildersltd.com/chrysler.html but picked up the old Dart instead. http://i294.photobucket.com/albums/mm87 ... 0_0636.jpg

Author:	SlantSixDan [ Fri Mar 28, 2008 11:15 am ]
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Quote: The 300 C is the best Chrysler ever built Uh...no. It isn't. You may like it the best of any, and it does some things well, and has some good characteristics, but it is definitely not the best Chrysler ever built, by any realistic set of criteria. Quote: Your friend may have a point with MOPAR's mid size junk, and the old K-Cars. Nope, he was talking about the current line overall. And, sadly, by objective measure and comparison, he's right.

Author:	Joshie225 [ Fri Mar 28, 2008 12:43 pm ]
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Dan, You mentioned a ground side electric choke modulator. Do you have any part numbers and see any reason it wouldn't work with a Holley electric choke? I was never completely happy with the electric choke on my 390 Holley even though it aspirated engine compartment air to provide some modulation. Since I'm going to have another electric choke Holley soon I'd like to improve the choke function. The deal in the past was simply the choke not opening fast enough when it was warm and opening too fast in the cold leading to seasonal adjustments on my part. Joshua

Author:	wjajr [ Fri Mar 28, 2008 1:31 pm ]
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Like a hand choke, one could install a rheostat in series with the choke heater feed, and dial in the desired heat curve while driving. You could retro fit a 2-13 channel dial from an old zenith for that 60's look... Can you say Quasar Control baby! Just kidding. My heap will be strictly a summer bomb, so one setting will work fine for me.

Author:	SlantSixDan [ Sat Mar 29, 2008 1:22 pm ]
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Quote: Dan, You mentioned a ground side electric choke modulator. Do you have any part numbers No, but if you see the Electric choke kits post and contact CarbsOnly, they can probably get you set up with just the modulator rather than the whole kit. Quote: and see any reason it wouldn't work with a Holley electric choke? No reason at all. Putting in a manual rheostat is not a practical or workable solution. You really do want the choke thermally controlled.

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Author:	wjajr [ Sat Mar 29, 2008 1:50 pm ]
Post subject:
Like a hand choke, one could install a rheostat in series with the choke heater feed, and dial in the desired heat curve while driving. You could retro fit a 2-13 channel dial from an old zenith for that 60's look... Can you say Quasar Control baby! Just kidding. Hey just a little potentiometer humor there...[/quote]