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1955 BUICK ROADMASTER; CHOKE ISSUE


Guest j.w.

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need help gentlemen

i know there have been several posts regarding hard starting for the buick

i have struggle w/ starting the '55 for a long time but i think it is better now.

this car has the accelerator start.

over the months i have been adjusting with the lean-rich knob on the 4 barrell carter carb.

.bottom line-i pressed the gas pedal to the floor once(the butterfly valve closed completely against the carb throat(like is is suppose to), then i turned the key on and pressed pedal -and ist started

right away.

question-on what setting should this choke adjuster be put on ??-mine is a 4 barrell carter,it has

4 marks to the left(lean) and 4 marks to the right(rich) of the mid-line setting(ribs).

what are the parameters for making this work perfect ??

thank you.

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There are 3 things involved with it all functioning properly. Idle mixture adjustment and idle screw adjustment, fast idle cam adjustment and choke adjustment. My only advice is to adjust all 3 by the book and then fine tune choke adjustment. You may want to be sure that the float bowl is full unless it has only set overnight. After sitting for a few days or weeks, the float bowl may not be full and this will cause a start and die condition which may seem like a choke problem when if fact it is not. If that is the case, it may start and die several times until the float bowl fills and then act normally and run ok.

Edited by TexasJohn55 (see edit history)
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I would agree with Texas John with the following possible modification:

The automatic choke is activated by a bimetallic coil like the one in many house central heat/air thermostats. Its cold position will depend on the ambient temperature. And the coil can fatique over many years of service.

Under conditions such as you describe (cold engine, and pressing the gas petal to the floor once) the choke butterfly SHOULD JUST TOUCH CLOSED AT AN AMBIENT TEMPERATURE OF 65 ~ 70 DEGREES F. A colder ambient, and there should be tension on the choke; a warmer ambient and the choke should not quite touch.

Thus, wait until the ambient is within this range, then adjust the choke. Once the choke is adjusted, adjust the other items mentioned in Texas John's post.

Jon.

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Two possible things going on here. As carbking states, the choke and starter relay is indeed activated by the electro magnetic setup attached to the passenger's side of the Carter 4 bb. carb. A maladjustment or a short in one of the two wires going to this will deactivate the internal plunger mechanism creating a situation of no starter engagement or improper choke activation. To isolate, have a helper get in the driver's seat and you operated the choke manually hugging over the carb as your helper attempts to start the car making sure the choke flap and the accelerator linkage is engaging properly.

Regarding the graduations marked on the choke spring canister. On a cold morning, release tension of the accelerator linkage arm connecting to the choke arm and let it spring back. Release the choke spring coil tension by backing off the 3 screws and place a free finger on the flap itself. Now turn choke assembly completely lean then back toward the full rich position then start to slowly back off until the flap appears to just close but has some slack tension. Then tighten the chokes 3 set screws, then slap the accelerator linkage open and shut again, then check the tension on the flap. It should be closed but just barely. This will give you a good starting point as the vacuum created by a cranking engine will move the choke open just a little more. Watch the choke flap as a helper attempts to now start the car. If there is overdue hesitation in starting use your finger to arch the flapper valve open just a wee bit and it should start. Now reset your choke spring with just a wee bit more tension.

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Two possible things going on here. As carbking states, the choke and starter relay is indeed activated by the electro magnetic setup attached to the passenger's side of the Carter 4 bb. carb. A maladjustment or a short in one of the two wires going to this will deactivate the internal plunger mechanism creating a situation of no starter engagement or improper choke activation. To isolate, have a helper get in the driver's seat and you operated the choke manually hugging over the carb as your helper attempts to start the car making sure the choke flap and the accelerator linkage is engaging properly.

Regarding the graduations marked on the choke spring canister. On a cold morning, release tension of the accelerator linkage arm connecting to the choke arm and let it spring back. Release the choke spring coil tension by backing off the 3 screws and place a free finger on the flap itself. Now turn choke assembly completely lean then back toward the full rich position then start to slowly back off until the flap appears to just close but has some slack tension. Then tighten the chokes 3 set screws, then slap the accelerator linkage open and shut again, then check the tension on the flap. It should be closed but just barely. This will give you a good starting point as the vacuum created by a cranking engine will move the choke open just a little more. Watch the choke flap as a helper attempts to now start the car. If there is overdue hesitation in starting use your finger to arch the flapper valve open just a wee bit and it should start. Now reset your choke spring with just a wee bit more tension.

GAAAK! :eek: There ain't electromagnetic setup on a stock 55 carb. The heat for the choke opening is from a heat pipe from the exhaust manifold and must be intact, patent and connected. Also the should be vacuum at the choke housing...lack of vacuum can be caused by crud buildup or improperly installed gasket between the base and bowl assy. Also be sure the choke pull off is working: vacuum at engine start activates a piston in the choke assembly tha pulls the choke blade open slightly to prevent loading up.

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Dear Tex GAAAK: We refer in our explanation of two entities. One being the Starter Switch mounted on the carb which is indeed a elector/magnetic item and the the other being the Choke Circuit which includes for our discussion a possible route in which one may go about properly adjusting it. However our discussion did not address the obvious namely the heat tube you have pointed out so graciously, which runs from the exhaust manifold to the Choke Circuit's thermostatic coil. That "heat pipe" of which you so passionately refer to, also runs on many models and years but we were not addressing that particular item in our discussion but thank you for pointing that out for the rest of us.

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Two possible things going on here. As carbking states, the choke and starter relay is indeed activated by the electro magnetic setup attached to the passenger's side of the Carter 4 bb. carb. A maladjustment or a short in one of the two wires going to this will deactivate the internal plunger mechanism creating a situation of no starter engagement or improper choke activation. To isolate, have a helper get in the driver's seat and you operated the choke manually hugging over the carb as your helper attempts to start the car making sure the choke flap and the accelerator linkage is engaging properly.

Regarding the graduations marked on the choke spring canister. On a cold morning, release tension of the accelerator linkage arm connecting to the choke arm and let it spring back. Release the choke spring coil tension by backing off the 3 screws and place a free finger on the flap itself. Now turn choke assembly completely lean then back toward the full rich position then start to slowly back off until the flap appears to just close but has some slack tension. Then tighten the chokes 3 set screws, then slap the accelerator linkage open and shut again, then check the tension on the flap. It should be closed but just barely. This will give you a good starting point as the vacuum created by a cranking engine will move the choke open just a little more. Watch the choke flap as a helper attempts to now start the car. If there is overdue hesitation in starting use your finger to arch the flapper valve open just a wee bit and it should start. Now reset your choke spring with just a wee bit more tension.

Being slightly familiar with 55 Buicks and very curious about the starting problem would you please explain the operation of the "electro magnetic switch" you describe. Specifically the magnetic aspect of the carb switch and how that interfaces with the switch's vacuum system. Also please point out to me in the 55's electrical schematic the exact location of the "choke relay" you mention. Try as I might I cannot find it. Would you also please describe exactly how the choke relay interacts with the vacuum/thermo-spring choke system. Thank you ..................Bob

Edited by Bhigdog (see edit history)
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Being slightly familiar with 55 Buicks and very curious about the starting problem would you please explain the operation of the "electro magnetic switch" you describe. Specifically the magnetic aspect of the carb switch and how that interfaces with the switch's vacuum system. Also please point out to me in the 55's electrical schematic the exact location of the "choke relay" you mention. Try as I might I cannot find it. Would you also please describe exactly how the choke relay interacts with the vacuum/thermo-spring choke system. Thank you ..................Bob

Hi Bob, I don't need no stinkin' wires to my choke!! But I have a 2bbl carb. I will wait for a reply to your post, I might learn sumptin.

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... .bottom line-i pressed the gas pedal to the floor once(the butterfly valve closed completely against the carb throat(like is is suppose to), then i turned the key on and pressed pedal -and ist started right away...

question-on what setting should this choke adjuster be put on ??-....

JW, if your car starts with one pump to set the choke, and a second pump with the key on, then it is set perfectly. Pay no attention to the marks on the side of the disc. They are of no importance.

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Uncle, uncle, uncle …. My post did not intend to imply the choke is wired, but admit due to late night typing that in the first line I did indeed state … the choke and starter relay is activated…. my bad and making it sound like both components are being activated by the starter switch and thus implying an electric choke, which does indeed screw up perceptions a bit if taken that way. No of course the choke is not wired and is a heat tube pipe type that heats the coil spring.

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