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rebuilt '55 ply 230 auto. with Langdon 2brl electric carb will not low idle


JPARK

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I have a rebuilt '55 ply 230 auto.  with a Langdon 2brl electric carb and intake manifold adapter (1 brl to 2 brl), will not low idle.  To try to get more power I split the exhaust manifold, put in a mild cam and had the engine bored 30 thou. over, and added dual exhaust. I have to keep the idle up so high to keep it running in gear at stops that it clanks at the rear end when I shift it into gear.  I checked vaccum--no leaks, tightened intake manifold bolts to torque--no use.  Anyone have any ideas how to correct?  John Park  

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It will still idle high in neutral.  We used carb. cleaner around the intake manifold and carb. adapter to see if the idle reved higher.  It did around the intake manifold so we tightened the bolts to torque. It didn't rev higher when we re-sprayed again. We used a vaccum gage to check the carb. vaccum, but not the manifold vaccum.  We have not tried going back to stock carb with no adapter yet.  Greg you know the guy helping me with this problem--John Stover.

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Ask him about Head Gasket / Vermont. Not familiar with carb or linkage but if adjusting idle screw has no effect, that suggests that the idle circuit is being over ridden. Is the throttle/s plate/s fully closed when gas pedal is leased?

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Have you talked to Langdon about this issue? I think he may know more than forum members about this carb. and what needs to be looked at with it.

 

DJ

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greg g  John doesn't like to talk much about the Head Gasket / Vermont mess.  He did say he had dinner with you guys a few years ago.  We will try the suggestions given.

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Check the rest of the tuneup, especially the timing.  You may have the carb opened up so far it's transitioning past the idle circuit.  If you've got the advance curve specs for the distributor, you should be able to calculate  timing regardless of the RPM needed to keep it running.

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All bets off if your motor is a turd (and many of them are, just worn out inside but still start and kina run, so)...but assuming a good motor and since you don't say what carb.  Lets assume DGEV 32/26 progressive and some basic adjustments applicable to all Weber carbs.  (Best carbs in the world.  Once vetted, toss out 6v positive and generator for 12v negative internal regulated alternator and HEI dizzy for 1/2 rotation starts and fuel injection performance.)

 

Notes:  all this is from experience, running DGEV 32/36 on an inline 6.  Webers are unlike your original carb.  Tiny changes make huge results in performance.  Vacuum leaks will kill performance and adjustability.  You will adjust for Lean Best Idle.  You will NOT be using the idle speed screw much....idle speed is mostly adjusted by the lean idle mix screw and jets.  If you ignore the ranges of adjustment on idle mix and idle speed for any given jet size it will idle too fast and never run right.  Get it right and your mileage and performace will go up noticeably.  Get it wrong and it won't plus you'll feel the primary to seconday stumble on the progressive model 32/36.

 

Your carb, if a 32/36 is likely jetted as follows and very close to right for the little flat head.  Primary idle jet is 60.  Secondary idle jet is 55.  Primary and secondary main jets are 140 and 140.  Don't mess with the emulsion tubes and emulsion jets unless you have a huge cam and are planning to only run at race speeds all the time.

 

You have four ranges to adjust.  Idle (primary barrel).  Then Cruise (primary barrel).  Transition (primary barrel and some secondary barrel.)  Wide open (both barrels)

 

This discussion is idle and cruise and generic to all weber carbs.  Transition and wide open may be fine with the installed jets I mentioned and not need much more tweaking. 

 

Remove carb from engine.

 

Screw primary idle jet in/closed.  Back it out no more than two turns.  (Its range of adjustment, no matter the primary idle jet size and with pure gas is 1.5 to 2.5 turns out.  Not more than 3 turns out on alcohol gas.  Anything other than 1.5 to 3 turns indicates your jet is too large or too small, change jets.  60 will be fine with the little flat head)

 

Quit screwing with the idle speed screw.  It ain't for anything but the finest final adjustment of speed.   Ensure the throttle plate is closed.  Back the screw all the way out.  Turn it in til it just touches the arm on the throttle plate.  Turn it in one more turn past first contact.  Period.  Its range of adjustment is from 0 to 1.5 or 1.75 turns in from first contact.  If you ever have to turn this screw in more than 1 3/4 turns with alcohol gas, your throttle plate is open too wide and you are idling fast on the transition circuit not the idle circuit.  Remember....keep the carb on the idle circuit when idling....i.e. throttle plates closed.

 

Reinstall the carb, do not hook up the linkage.  Make sure the throttle plates are closed, no interference.

 

Install the linkage, make sure the throttle plates are closed.  99% of fast idle is either forkin with the idle speed screw when you shouldn't or the linkage is pulling the plates open too soon, moving you off idle circuit to transition circuit or you have a vacuum leak.

 

Start the car.  It should idle low and slow like a tractor.  You'll have to stay with it till its warm and can idle low and slow on its own.  The weber will idle your engine easily down to as little as 250ish RPM.

 

Don't be tempted to fork with the idle speed screw....leave it the hell alone.

 

Turn the primary idle mix screw in or out in 1/4 turns waiting 15 seconds to note a change in rpm and smoothness.  Find the smoothest HIGHEST idle between 1.5 to 3 turns out, your final adjustment here it to turn the screw in about 1/8 turn (lean) for lean best idle.

 

Check your idle speed on the tach.  It should be higher.  If its close now adjust the idle speed screw.  Tiny turns in to increase the idle or out to decrease the idle to about 500 RPM with a manual transmission.

 

Still smooth?  Good.

 

Go back to idle mix screw on the primary....adjust it in 1/4 turn increments to achieve highest/smoothest idle, then turn it in (lean) just 1/8 turn.  You'll probably find that there is no significant change so put it back where it was ( remember the range for the primary jet of any size is 1.5 to 3 turns out (rich) from the bottom) just before you did the tiny tweek on the idle speed screw.

 

Check dwell and adjust as needed.  Check timing and adjust as needed.

 

If you changed dwell and or timing, go back and tweak the carb once more.

 

Check and fix all vacuum leaks.  If you fix a leak, readjust the carb.

 

(I put dwell, timing and vacuum leaks last since you seem to have the carb off the engine.  So, figgered you should get it running.  After fixing any of this on a running set up, you can go back and check/tweak the carb to lean best idle and idle speed upon completion of any corrective actions.)

 

Button it up and go drive.

 

It should be awesome on starts, idle (no lean idle miss), it should cruise with good power and very snappy response.

 

Once this is done, you move on to tuning the transition and secondary as and if needed.  If the car seems to bog or slump then roar when going into the secondary (secondary throttle on the 32/36 begins to open about 60% throttle) you probably need to:

 

1.  Ensure your linkage not only lets the plates fully close at idle, but opens both full at WOT.

 

2.  Possibly go larger on your secondary barrel main jet, 145 to 165 ought to be way big enough for the little flatty.  Note:  The little 55 jet at the bottom side of the secondary barrel is fine....leave it alone.

 

Once the weber is right, install a large size (fuel injection filter before the bowl as it is sensitive to dirt.)  If your fuel pump is putting out more than about 5 or so lbs, install a regulator and get it down to 3.5 or so lbs.  After that....forget about the carb.  It'll last and hold adjustment longer than you and your kids will have the car.

Edited by Sharps40
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Redline weber has a nice data sheet on adjusting the webers that reads mostly the same as above.  It also give you a nifty sheet of paper to record your jet sizes and adjustments for future reference.  Again....if its a weber, otherwise all this typing is wasted!  :)

 

http://www.carburetion.com/Weber/adjust.htm

Edited by Sharps40
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Sharps40,

Yea, Tom is no help at all.  No instructions included with the carb!  I don't think he even knows the specks for the carb.  I might be able to get the info from a Ford service book.   When I first got the carb, the upper jet was installed up side down and was sqirting the gas out of the carb into the air cleaner, instead of down the opening.  Had to turn it over to get it to work.  This was supposed to be a rebuilt carb that he personally checked out himself.  We will try all of your suggestions.  Thanks for the info.  We are going to put the original 1 brl. back on to see if it still persists then go from there.  John 

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Sharps40 My carb is motorcraft. What are the chances that the specs. are the same as the Webber? John

Interesting. Mr Langdon used to have the carter webers that were for the slant six engines.    Sharps40 pretty much nailed the tuning instructions on them. I wished I had read his blog about 10 years ago.  I ran mine for years. I found a good carter ball and ball truck carb at Spring Carlisle and decided to switch back and compare. For all the talk about how great the performance was. For all the talk about better fuel mileage. In my case it was not relevant. The ball and ball was almost identical if not a touch better fuel mileage and definitely had had better performance. Ive since moved to dual carbs and dual exhaust made by Mr Asche and that really stepped it up a notch. An honest 5 miles per gallon better and a noticeable increase in performance. I know that isn't necessarily a good carter weber verses carter ball and ball item although I did stick with the ball and ball versions for the dual setup. 

 

You did pay good money John. Maybe you can send Sharps40's tuning instructions and the reference sheet to Mr Langdon in an email and ask

him if it would be relevant to the carb you got from him.  I know Mr Langdon has sold a big number of the carter webers to Plymouth owners. He should

be able to help you out. If not if you can get your money back the ball and ball carbs are not a bad alternative and I think a better one. I am not 100% sure

if the current pricing from Mr Asche. Mine was $150 when I got it and it looked like it was brand new even though it clearly was not.  He had rebuilt

it.

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Tom always calls me on Sunday's. We talked a bunch on the 3236 as i was tuning it in. 2 bbl carbs are not for folks that can't/don't have time to set em up. Once tuned they are amazing. But they are very different and amazingly adjustable. Especially the Webers. 3236 is my go to carb for any inline 6 I love them!!!

Edited by Sharps40
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