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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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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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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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Discussion Starter · #5 ·
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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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: http://www.hotrodders.com/forum/electric-choke-193337.html#post1383257

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.
 

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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.



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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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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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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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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At this stage, I'm not too sure who is responding to who so I'm out of here except to say again that regardless of what it says in "Holley Carburetors & Manifolds", there are better ways to wire an electric choke than to use the ignition/coil 12V power wire. If for no other reason, using the ignition power circuit will allow the choke to heat if the key is "ON"- even w/o the engine running.
 

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I know what color the dizzy wire is...... and yes I say run a new wire right beside the dizzy wire and tie in at the switch, if that's what he wants, and not splice into the dizzy wire.......I've stated my opinion and don't agree with yours.......

Reguardless....thanks for the vet wiring dia.... didn't have that one in my Archives
 

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Discussion Starter · #18 ·
Thanks for the replies guys. It is a Holley carb and HEI dizzy. My thought is to add the in-line fuse just behind where the wire plugs into the choke. This wire will feed back and splice into the ignition controlled feed wire into the dizzy. But after reading the replies, I don't think this is the best way.
 

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Thanks for the replies guys. It is a Holley carb and HEI dizzy. My thought is to add the in-line fuse just behind where the wire plugs into the choke.

Put the fuse as close to where you connect the wire as possible..., and not where the choke is.

If you cut into/melt the wire, for whatever reason, creating a short and the cut/melt falls before the fuse (i.e., because fuse is at the choke), the fuse does you no good.

Agreed with all that there are better ways to connect the electric choke, and the Holley Carburetor and Manifold Manual outlines some of those also (e.g., the alternator tap so it only operates when the engine is actually running).

But the OP was trying to keep this as simple as possible using only the ignition and based on the parameters he provided, the suggested method is perfectly acceptable, though maybe not to everyone's liking.

When I had this carb on my car, I did connect the choke to a "switched" fuse on the panel and even had an "off" switch under the dash to disable it for whatever reason.

'nuff said.
 
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