Hi guys I was wondering if anyone could tell me the best way to temporarily bypass the alternator for drag racing. I would like to be able to switch it off during the run, and back on immediately after the run. I wasn't sure if you interrupt one of the field wires, or how you do it. I used the search, but I couldn't find anything. Any help would be great, trying to get ready for the mason dixon race.

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Ryan Covalt
62 Plymouth Valiant Race Car 2170# 11.008 @ 117.65 MPH 1/4 Mile Best
72' Dart Swinger Street Car, 4 spd, 3330# 14.061 @96.58 1/4 mile Best

I interupted the main battery wire.Mine is a 1 wire....but as long as you interupt the charge, it should just "spin".

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Wife's: 64 Valiant
My: 70 Road Runner, 67 Barracuda, AND the 62 Valiant drag car!!

If you switch off the B+ (switched battery power from the ignition switch) that feeds the regulator the alternator will just sit and spin.

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Joshua

You sure? Less mechanical drag on the engine, yes, but also lower line voltage which means poorer ignition performance which could cancel out or reverse the benefit of cutting out the alternator. Do some back-to-back trials during a test-and-tune session to see which way works best for you.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Thanks for the answers guys. Dan I will try what you said, and run it back to back. My battery just went bad (it was 8 yrs old). So I got a battery with heavier plates, it is supposedly able to hold more a more consistent voltage when power is disconnected. The ignition system is a msd 6al2 Programmable version, and the manual says it needs a consistent 12+ volts to perform properly. Hopefully it helps, i'm looking for tenths where ever I can find them.

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Ryan Covalt
62 Plymouth Valiant Race Car 2170# 11.008 @ 117.65 MPH 1/4 Mile Best
72' Dart Swinger Street Car, 4 spd, 3330# 14.061 @96.58 1/4 mile Best

Do you have an electric water pump drive? It saves a lot more power than cutting out the alternator. If you have enough room between the raditor and the water pump pulley it is pretty easy to rig it up so you just use it at the strip. Mr. Gasket and Moroso make kits to do this.

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If you didn't drive it there, it's not a street car.

I have a full throttle "micro" switch on the carb. When I go WOT the sw opens the alternator field wire.

Dan and I disagree on a WOT alternator cutout. If you have a good battery, it will carry the electrical load fine, for the 17 seconds or less, at WOT.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

I don't say the battery won't handle the load. I say the line voltage will be higher with the alternator active. Whether that improves ignition performance enough to make up for the drag of turning the alternator on any particular car is a matter for experimentation.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I don't have an electric water pump drive. I never really looked into them before. I just looked at the universal moroso kit, what else is needed to get that kit to work on a slant six? Do you fabricate your own brackets to mount the electric motor? Could the electric water pump be used on the street, or would it be best to set it up to run both ways?

What type of micro switch is used for the cutout? is it a normally closed switch that is held in the open position at WOT? Similar to a nitrous activation switch?

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Ryan Covalt
62 Plymouth Valiant Race Car 2170# 11.008 @ 117.65 MPH 1/4 Mile Best
72' Dart Swinger Street Car, 4 spd, 3330# 14.061 @96.58 1/4 mile Best

I used a Ford waterpump pulley (slightly smaller diameter with a spacer/adapter mounted behind pulley) that way could run a smaller length belt between crank pulley and alternator and had a pulley made to fit electric motor. That way I can run stock system on sreet and run two belts at the strip.

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Part of Tyrde-Browne Racing

The Moroso kit will work fine. I think, all I had to do was shorten the water pump pulley, so it didn't rub on the WP body. Do not run this setup on the street. These motors are nothing more then heater "blower" motors, and are not designed for the amount of side loading the belt puts on the bearing, or the amount of current drawn in this type of usage. You would be replacing the burned up motors on a regular basis. I have it on my street strip 66 Cuda, and toasted a couple of these motors just going to cruises. They will work OK for the short running time, of a drag car.

For just a WOT cutout switch, just use a normally closed switch (many NOS switches are just normally open. You can buy switches that have both NO and NC contacts). When you go WOT it will open the field circuit, and turn of the alternator. On my car I use a NO switch (since I have nitrous) at WOT the switch operates two relays. One turns on the nitrous, and the other turns off the alternator

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Charlie,

I understand the relay concept and I just installed one on Ryan's Dart for the Electric fan. I understand your micro switch triggering the 2 relays (Nitrous & Alternator) but doesn't the alternator relay require a little different wiring? You use the relay to break the circuit instead of complete it, correct? If you could enlighten a "electrically challenged" dad I would appreciate it. I'm sure I will be helping install the cut-out for Ryan. I guess these are the standard 4 prong relays?

Thanks, Rick

Actually they are 5 prong relays. They can be wired up either NO or NC. The micro sw, "triggers" both relays, one is wired NO for the nitrous, the other is wired NC for the alternator. If you are just planning on operating the alternator field, you do not need a relay (doesn't hurt). Just wire the micro switch as normally closed.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Thanks for the info guys, I will have to look into these some more. I like the micro switch idea (one less switch to remember to turn back on) hopefully I will be able to get my car ready and try some of these things for the mason dixon race. Thanks alot.

Ryan

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Ryan Covalt
62 Plymouth Valiant Race Car 2170# 11.008 @ 117.65 MPH 1/4 Mile Best
72' Dart Swinger Street Car, 4 spd, 3330# 14.061 @96.58 1/4 mile Best