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Old 03-06-2009, 09:12:07 AM   #1
jamieg285
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Holley electric choke - pull-off adjustment

Can anyone give instructions on how to adjust the choke pull-off on a Holley electric choke?

I have established that my hard starting problem is most likely caused by this being wrong, but I haven't been able to find any decent instructions on how to adjust it. I have a later model choke, where the adjustment is with an external screw, not a bendable tab inside the housing.
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Old 03-06-2009, 06:43:05 PM   #2
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Don't think I've ever had to fiddle with the pull off... just loosen the three screws that hold the black plastic part in and with the throttle slightly open, and the engine cold, just turn the plastic part one way and you'll see it open the choke, turn it back so the choke plate is just closed.

Here's a pretty good rebuild article.
http://www.kitcarmag.com/techarticle...ech/index.html
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Old 03-06-2009, 08:22:20 PM   #3
Stroked72SS
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I always "Pull them off" and throw them away...With the Carb adjusted right, a choke isn't needed
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Old 03-09-2009, 08:17:14 AM   #4
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Anyone know?

Neither of these suggestions will help me.
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Old 03-09-2009, 08:37:43 AM   #5
phbmd
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Jamie,

The Holley Website has literature for rebuilds, choke kits, and has carb. owners manuals. They also have techs available by phone - I have called a couple times for help after rebuilding my 4160 and changing to electric choke.

My electric choke had only two adjustments. You adjusted the fast idle speed when the high lobe on the fast idle cam contacted the adjustment screw. You also adjusted the chock duration by loosening the three screws on the housing and turning the black cover. Winter is just ending in D.C. and the choke seemed to do it's job pretty well after those two adjustments were made (started right up in the cold and ran at 1400 rpm - and I could kick it down after only a minute or so).

I guess you can be a total radical : ) and have the choke close minimally but adjust the fast idle speed on whatever cam lobe the screw is contacting at that point. But the standard adjustment method worked in my case.
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Old 03-09-2009, 08:41:06 AM   #6
BondoSpecial
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If your car will run fine cold with no choke, it's set up too rich.

I didn't think the Holley had a "pull off" (like the vacuum break that Qjets use, when the car first starts, it opens the choke flap a preset amount, that is adjustable)
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Old 03-09-2009, 10:02:49 AM   #7
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Any "automatic" choke is adjusted in this manner: loosen the screws (usually three of them) to that you can rotate the cap where the bi-metal is. The engine should be cold (you can also use a cooling agent like ice to cool the thermostat down), adjust the choke mechanism so that it is just closed by turning the cap on the choke. I've used this method before and it is usually close to what the engine needs for a choke adjustment. The only variable in this is the outside temperature. If it's VERY cold outside, you may have to back off on the closed adjustment a little. Conversely, if it is VERY hot out, it should be OK the way you adjusted it but you may have to back it off a little to compensate for cold weather. After all, the idea is to have it open as the engine warms up, not to stay closed forever!
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Old 03-09-2009, 10:05:50 AM   #8
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the problem is that without a vacuum break for the choke, like a qjet has, on some applications with a bimetal choke actuator, in order to get enough choke "on time" by turning up the preload on the spring, the choke plate will then end up so far shut, that the car will load up and run way overrich for the first few minutes until the choke starts to open. Edelbrocks have a spring loaded plunger in the choke flap, to semi-remedy this, but the Qjet choke pull off is the best electric choke setup ever used.
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Old 03-09-2009, 10:06:18 AM   #9
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Quote:
Originally Posted by 1977_TPI_Camaro
If your car will run fine cold with no choke, it's set up too rich.

That's not what my Wideband says...
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Old 03-09-2009, 10:16:09 AM   #10
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Wow, a flurry of activity, but sadly still no answer.

I understand how everything is supposed to work. The block cover controls how quickly the choke opens, not how it reacts on immediate startup. The fast idle cam again, controls the idle speed in relation to the choke position. Neither of these are the problem.

The problem I have is on immediate fire up, the choke should open a fraction from fully closed, under the influence of the increase in vacuum. This is known as the pull-off, and should be adjustable, controling how much the flap will open at this time - totally independant of the black cap or fast idle settings.

There are some instructions in the Holley documentation, but it is only for the older style, where you adjust a tab inside the housing. I have a newer one, and there isn't a tab to bend, just a screw. I don't know if this screw is the adjuster, or is a lock screw, or even something else. I don't know how to adjust the thing to get it to the right setting (which, for initial setting) is going to be 1/4 from fully closed.

I've emailed Holley, but had no response yet, so may call them later today, but still hope that someone may have the answer anyway.
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Old 03-09-2009, 10:18:11 AM   #11
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Do you have a pic of this screw? You are talking about the same thing I am thinking of that the Qjets have, the pull off for the choke, but I was not aware it was adjustable on the holleys. I'd be interested to know

Steve
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Old 03-09-2009, 11:35:56 AM   #12
jamieg285
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This post has picks with the same setup
http://www.chevelles.com/forums/show...pulloff+piston
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www.mfatw.com/WD 'WhiteDream' 79 Camaro Website

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Old 03-09-2009, 12:52:02 PM   #13
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Oh wow cool.

So heres how I would adjust that. You adjust the bimetal spring tension, by timing how long it takes your engine, dead cold, to open the choke completely w/ the engine idling. I shoot for something like 4 minutes, at around 60 degrees F. If this much spring tension causes the choke to snap 100% closed when the car is cold, turn that choke pull off screw until you have maybe 1/8" gap between the choke plate and the horn (car still cold). Test and see if the car runs lean enough when first started, with that setting.

You will have to mess with the tension and pull off screw together. Messing with one will affect the other.
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Old 03-09-2009, 01:01:15 PM   #14
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What you are playing with is the set/lock screw for the factory-set pre-load on the bi-metal coil spring. It is a pull-off piston. If I recall, there is a small plunger and spring inside that housing, and the factory uses it to put some initial pressure on the bi-metal coil spring. and the pull off assembly. As the bimetal sping loses tension from heat/cold, the plunger can be extended a bit to place more pressure on the spring. Don't mess with it. There needs to be some preload pressure on it Do you know the paperclip trick to adjust this? http://holley.com/data/Products/Technical/199R8339.pdf

You adjust the choke with the black cover that houses the bimetal. Loosen the 3 screws and rotate the housing such that you release pressure on the choke blade. If the engine vac isn't immediatly pulling the choke blade open 1/16 to 1/8 in, then you have too much pressure on it. I always set mine so that the blade BARELY closed. Even vac created from cranking would make it pulse open with each cylinder. As soon as it caught, the blade was open about 1/8". Now set the high-idle speed. After it will kick-down, then reset hot idle speed. If the choke opens too much at cold-start, add some pressure the system by taking the housing back the other way. I always went is VERY small increments of 10 degrees rotation.

Last edited by Bikefixr : 03-09-2009 at 01:09:21 PM.
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