Sticking Solex Carb Throttle Shaft

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Sean M Rooks
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Sticking Solex Carb Throttle Shaft

#1 Post by Sean M Rooks »

Hi all,

Having a weird problem with my carb on the driver's side. I experienced this every time the engine was cold when starting it this past winter, and now after tweaking the idle (which was high at 1400 when warm) it seems to be persistent -- When cold at first start (even in 80 degree ambient temps) and even when driving around (coming off idle).

I took a quick video of the "when cold" behavior: https://www.youtube.com/watch?v=3hHvzqdGUdc

Any thoughts? The carbs were supposedly rebuilt with new throttle shaft bushings when I bought the car 4 years ago and this issue just presented this past winter.

I am going to try and do another tune up sometime this week or weekend to see if that clears it up but would appreciate any advice. couldn't find any similar symptoms in the search.

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Thomas Sottile
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Re: Sticking Solex Carb Throttle Shaft

#2 Post by Thomas Sottile »

I would take the carb off and check for any dirt or whatever in the the way of the butter fly or shaft, spray a little solvent in the area.and check the screws which hold the butter fly make sure they are tight. good luck.

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Greg Bryan
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Re: Sticking Solex Carb Throttle Shaft

#3 Post by Greg Bryan »

Also, check the orientation of the pull-off spring. If installed in the wrong orientation, the long straight side of the spring can catch on the throttle shaft at full throttle. Doesn't sound like this is your problem, but worth checking.
Greg Bryan

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Wes Bender
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Re: Sticking Solex Carb Throttle Shaft

#4 Post by Wes Bender »

If the person who rebuilt the carburetors loosened the butterflies, one or both may not be aligned correctly in the throat. When you reduced the idle, you let them close a bit more and one or both might be sticking now, more than before. If you decide to loosen the screws on the butterflied to better align them, make sure you stake them again after tightening.
Some days it's just not worth chewing through the restraints.....

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Re: Sticking Solex Carb Throttle Shaft

#5 Post by Dick Weiss »

You must check the throttle return action after the engine and transmission are warm/hot. Shut off the engine, pop off the link rods from the carb arms, and raise the ball socket(s) from the ball ins. The sockets should be approx. 1/16" (1,5mm max.) above the pins so the growth of the engine and trans. won't take up any slack in the throttle linkages and hold the carbs open above idle RPM. You may have to readjust the idle stop screws 1st; Then do the check mentioned above. Also, make sure the carbs are balanced properly @ 2500-3000(?); Then @ 850-900 idle

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Sean M Rooks
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Re: Sticking Solex Carb Throttle Shaft

#6 Post by Sean M Rooks »

Thanks everyone!
Dick Weiss wrote:Shut off the engine, pop off the link rods from the carb arms, and raise the ball socket(s) from the ball ins. The sockets should be approx. 1/16" (1,5mm max.) above the pins so the growth of the engine and trans. won't take up any slack in the throttle linkages and hold the carbs open above idle RPM.
Dick - so to clarify, I may have goofed when having a mm or so of slack in the linkages when cold, engine off? Sounds like getting that slack when HOT is the right procedure? I'm spatially challenged sometimes.

I'll see if I can get to this one night this week, as it's going to be in the 90s this weekend and standing behind an aircooled motor pumping exhaust hot in my face doesn't sound like too much fun. My wife already complains I smell like fumes all the time.

I'm pretty sure I did the idle adjustment with engine hot right after getting home from my drive to work, but it's entirely possible I goofed and did it cold. My memory is hazy so I'll go through the whole tuning procedure again to be safe.

-Sean

Dick Weiss
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Re: Sticking Solex Carb Throttle Shaft

#7 Post by Dick Weiss »

Thanks for your reply Sean,

You'll have a little more slack (after you make the fore-mentioned adjustment when hot) when cold, but it'll lessen when the engine and trans. warm up. You don't drive @ idle.

Enjoy the driving season,
Dick

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Sean M Rooks
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Re: Sticking Solex Carb Throttle Shaft

#8 Post by Sean M Rooks »

Hi all,

Many thanks for the advice and help. I managed to spend Saturday morning out in the garage and started with a general tune up. I did the valves first, then timing, then adjusted the carbs.

Apparently my timing was off a bit. I'm guessing I nudged it somehow when I had the engine out last - also the timing adjustment has always baked my noodle. But I think I finally have it set right. I did notice that the replacement new rotor seemed to have a little bit of play in it on the shaft. I replaced it with a Bosch marked part I had and it fit snugly. Springs snap back OK but I have a feeling they might be a little tired.

I took the offending carb off and checked it out. I didn't see anything wrong with it (butterflies were tight on the shaft), but noticed the idle adjustment screw was all the way out so the throats were pretty much completely closed. I adjusted it so it was in half a turn from just touching, reinstalled the carb, and did same to the passenger side.

Got her running and she purred. Quieter valve train, sounds better. Warmed it up with a quick ride to warm it up. I had to adjust the idle again but this time it only took small adjustments to get the idle down to between 900 and 1100 when hot.

The car starts easier now, seems to have a little more power, and neither carb is sticking when I let off the gas, cold or hot. Hopefully it'll stay that way!

Sean

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Wes Bender
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Re: Sticking Solex Carb Throttle Shaft

#9 Post by Wes Bender »

"Hopefully it'll stay that way!"

It won't. That's why Ron and many others always say to give it a tuneup before tearing things apart chasing a problem. Modern engines can go a long time between tuneups, but not these engines.
Some days it's just not worth chewing through the restraints.....

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Wes Bender
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Re: Sticking Solex Carb Throttle Shaft

#10 Post by Wes Bender »

... and one more piece of advice if I may. Every time you change oil or give the car a tuneup, if you have a throttle cross shaft in front of the fan housing, put a dab of chassis lube on the end ball joints.
Some days it's just not worth chewing through the restraints.....

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Sean M Rooks
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Re: Sticking Solex Carb Throttle Shaft

#11 Post by Sean M Rooks »

Wes Bender wrote:"Hopefully it'll stay that way!"

It won't. That's why Ron and many others always say to give it a tuneup before tearing things apart chasing a problem. Modern engines can go a long time between tuneups, but not these engines.
Well, yes, understood. And that's why I started there! I just meant that I hope the issue doesn't return after a drive or two.

Car has fresh grease on the linkage ball joints from when the engine went back in the car back in early March (plus a brand new new pull rod down under) but also a good tip. Chassis was lubed recently too (every 1500 miles - same as oil changes although I've been ahead of that of late). New oil prior to my Hershey trip. I try to take good care of her. Parts are expensive. "That pair of pants costs as much as a new Michelin!" "I could get a new distributor cap for the price of that T-shirt!" :)

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