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Old 08-25-2012, 02:16 PM
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In line fuse?

I am installing an in line fuse where the electric choke wire hooks up to the carb. I will be using a spade type fuse. What amp fuse would be best?

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Old 08-25-2012, 03:18 PM
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I would say 15 amp should be adequate. If you have a DVOM you can check how much current it draws when heating (powered up) and put a fuse in that is 20 percent larger than the max current draw of the heater element.
Be sure the choke element is good and cold when you test it, as it warms it draws less current. LA
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Old 08-25-2012, 07:30 PM
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new device

The choke circuit should be fused at the fuse block.
Are you adding another load to that circuit? If so what is the amp load of the added device?

vicrod
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Old 08-25-2012, 08:13 PM
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I measured the resistance of my electric choke Holley 650 dp and when cold, the resistance is 22 ohms. Theoretically, as the thing heats up, the resistance should also go up, unless the bi-metallic strip is exhibiting some weird electro-chemistry. So 22 ohms will serve as our reference point.

Let's say when the engine is running, it puts out 14 volts.

14 volts / 22 ohms = 0.63 amp.

So the total us is under 1 amp and any existing fuse would probably have the excess capacity to carry this small bit of current.

So why fuse?

You fuse something, not to protect it, but to protect the wiring in the case that the component should fail catastrophically (i.e., short out) or if the wire chaffes on a ground.

So, if you use a similar gauge of wire, or even one size smaller, the existing fuse on that circuit will protect your wire leading to the choke and the fuse really does you no good except complicate your set-up.
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Old 08-26-2012, 12:56 PM
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There is no choke circuit wiring on the car and the wiring for the oil warning light is long gone. I was going to tap into the 12v ignition source that fires up the dizzy. The fuse is there for protection, in case the wire ever was to come off the electric choke.
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Old 08-26-2012, 06:12 PM
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As shown, a 1 amp fuse should be sufficient. That said, assuming that you use at least 18 gauge wire, you could use any value up to 10 amps without problem.
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Old 08-27-2012, 08:25 AM
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Quote:
Originally Posted by Madmax305 View Post
There is no choke circuit wiring on the car and the wiring for the oil warning light is long gone. I was going to tap into the 12v ignition source that fires up the dizzy. The fuse is there for protection, in case the wire ever was to come off the electric choke.
Don't draw current from the distributor. More: electric choke

Edit- If this is a Q-jet, be sure there's a good ground when measured between the metal rivet that holds the choke heating element together and the negative terminal of the battery. It grounds through contact between the choke housing mounted to the side of the carb and the choke heating element. Don't use a gasket between the heating element and housing- that gasket is for the hot air type choke.

Last edited by cobalt327; 08-27-2012 at 08:35 AM.
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Old 08-27-2012, 11:10 AM
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Quote:
Originally Posted by Madmax305 View Post
There is no choke circuit wiring on the car and the wiring for the oil warning light is long gone. I was going to tap into the 12v ignition source that fires up the dizzy.



If you do this, be sure and tap into the wire after the ignition switch, but BEFORE the ballast resistor. You could actually take it from the ballast resistor terminal BEFORE it goes through the resistor.

If you tap into the wire after the resistor, both the ignition system and choke will be competing for the available current.
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Old 08-27-2012, 04:16 PM
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wouldn't advise using that wire...... if you have a malfunction at the choke and it blows/fries..... you could loose your ing source..... which is bad......lol
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Old 08-27-2012, 06:28 PM
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Which is why he would put the fuse in. That is among the most common places to wire it.
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Old 08-27-2012, 06:44 PM
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No it's not and if the thing fried you had better hope the ing doesn't go with it..... might suck going down the road at 60 mph........ much better to run a new wire back to the fuse block and it would cost what a buck or buck and a half for the extra 3 feet of wire....... not worth the risk IMO
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Old 08-27-2012, 07:01 PM
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OK, quoting from Holley Carburetors & Manifolds, 1987:

"The advantage of an electric choke is simple hook up without plumbing of other mechanical attachments to the engine. Only a single wire is needed, usually from the ignition switch."

But that's just their opinion.
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Old 08-27-2012, 07:17 PM
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W/all due respect, I know of nobody who has wired the choke to the ignition switch itself. There is just no need.

The wire for the wiper motor is sometimes used, otherwise (and ideally) the choke heat will not come on unless the engine is running. To do this, the alternator can be used to trigger a relay or an oil pressure switch can be used to power the choke so it doesn't heat up w/the key in the "ON" position unless there's oil pressure or alternator output- as in the engine is running. Most other schemes will allow the choke heating element to heat up w/the engine not running- like running the choke heating element off the ignition switch, or any other circuit that it hot w/the key in the "ON" or "RUN" positions.

The fuse box often has auxiliary or "accessory" terminals that are fuse protected. These circuits can be used as long as care is taken to not turn the key "ON" w/o starting the engine if the choke is needed.
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Old 08-27-2012, 07:24 PM
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You are funny.... I have no issue wiring it from the ing switch..... I think it's wrong to wire it into the dizzy feed wire and wouldn't advise anyone to do it... period! and that's my opinion!

Last edited by EOD Guy; 08-27-2012 at 07:30 PM.
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Old 08-27-2012, 08:43 PM
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You're goofing on us right?

The ignition switch wire is the same thing as the dizzy wire only separated by the length of black/pink wire and the ballast resistor.

So all he would be doing is paralleling an existing wire into the engine bay.

http://www.keystonestatecorvetteclub...tte%201964.pdf
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