New carburetor, new noises. - JeepForum.com
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post #1 of 10 Old 09-19-2020, 12:06 PM Thread Starter
Horatio
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New carburetor, new noises.

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My old carburetor had numerous issues and appeared to be original. The choke wasn't setting correctly, it was gummed up, and it ran very rich. I decided to pull the trigger on a rebuilt carb from national carburetor so that I could be up and running quickly and so that I would have a spare carburetor to rebuild and learn on.

With the rebuilt carburetor the jeep immediately runs better. It starts up instantly into a strong 900-1000 rpm warm up idle and then settles into a solid 600-700 rpm idle. I set it up using the spark CTO to switch it from ported to manifold vaccuum after warm up. I have removed the air injection and EGR components. The EGR valve remains but is disconnected and capped.

What I'm noticing now is ticking sound. It almost sounds like lifters ticking, but louder. It will also diminish after warm up, possibly after the CTO switches to manifold vacuum. Does this sound like an advance issue? Should I run off manifold vacuum only?

Unassociated with this ticking sound is an intermittent stumble. The engine will jump lightly while in idle, and there is a subtle and concurrent thumping sound at the exhaust pipe. Is it missing? Detonation/pre-ignition?

I'm much happier with how it runs now. it pulls strong, idles well, and I can now crawl in first gear where it would have stalled before. The garage no longer smells like I've spilled a gallon of gas on the floor which keeps my wife happy.

All in all, it was a great fix, but it's not quite 100% yet.

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post #2 of 10 Old 09-19-2020, 05:02 PM
JEEPFELLER
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Are you using a dwell/ tach meter or vacuum gauge to find the sweet spot for the mix screws? Are the mix screws evenly out the same turns? It's impossible to wing this/ do it by ear.

Have you looked for vacuum leaks?

See post 6 in https://www.jeepforum.com/forum/f8/c...gnose-4402381/

What have you found out?

----JEEPFELLER
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post #3 of 10 Old 09-19-2020, 07:44 PM
cjoffroad
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Ticking can be a slight exhaust leak somewhere. Un-related to your carb but more than likely due to something you've worked on recently.
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post #4 of 10 Old 09-19-2020, 08:53 PM Thread Starter
Horatio
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Quote:
Originally Posted by JEEPFELLER View Post
Are you using a dwell/ tach meter or vacuum gauge to find the sweet spot for the mix screws? Are the mix screws evenly out the same turns? It's impossible to wing this/ do it by ear.

Have you looked for vacuum leaks?

See post 6 in https://www.jeepforum.com/forum/f8/c...gnose-4402381/

What have you found out?

----JEEPFELLER
Yep, I'm 1.5 turns out on both sides. All the vacuum lines have been replaced and there are no leaks.

I did verify the ticking during a cold start today. While ticking I switched between ported and manifold vacuum. No change. It is definitely more pronounced during the high idle during warm up. I don't notice it while driving.

I'm still learning, and having a great time. Really appreciate the help.
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post #5 of 10 Old 09-19-2020, 08:54 PM Thread Starter
Horatio
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Quote:
Originally Posted by cjoffroad View Post
Ticking can be a slight exhaust leak somewhere. Un-related to your carb but more than likely due to something you've worked on recently.
I did consider this because of my recent EGR and air injection delete, but assumed because it comes and goes that it was not an exhaust leak.
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post #6 of 10 Old 09-19-2020, 09:21 PM
JEEPFELLER
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You are using meters/ gauges?

What is the timing set at? (W/ the advance hose temporarily taken loose and plugged off)

-----JEEPFELLER
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post #7 of 10 Old 09-19-2020, 11:00 PM
pedal2themetai
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HI an exhaust leak WELL come and go.. its starts when the motor is cold and then as it heats up and parts swell it seals its self off and goes away.
good luck
tim
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post #8 of 10 Old 09-20-2020, 09:42 AM Thread Starter
Horatio
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Quote:
Originally Posted by JEEPFELLER View Post
You are using meters/ gauges?

What is the timing set at? (W/ the advance hose temporarily taken loose and plugged off)

-----JEEPFELLER
Not yet. Need to purchase a timing gun. I was originally wondering if the ticking was associated with the EGR and air injection deletes, and possibly vacuum advance issues because of my modifications. The ticking was not there with the old carburetor and EGR components installed. I'm now realizing I need to spend some more time ensuring that the ignition timing is correct before I mess with additional adjustments to the new carburetor. I need to spend more time reading the service manual and online with some basic auto mechanics pages.
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post #9 of 10 Old 09-20-2020, 11:57 AM
JEEPFELLER
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You don't need anything special with knobs or buttons----plain Jane works fine. trigger is all you need.

Sometimes I'll use my Grandpa's timing light from the '60s, the one's with all of the extra bells and whistles are just that much more confusing to use.

I see these at yard sales and in pawn shops dirt cheap!

Without a way to check/ set stuff, your Jeep may run and run decent, you probably won't really get full potential out of it.

----JEEPFELLER
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TUNING TOOLS.jpg   HARBOR FREIGHT.jpg   CAR QUESTION PICS 022.jpg  
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post #10 of 10 Old 09-20-2020, 06:40 PM Thread Starter
Horatio
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Location: Peachtree City
Posts: 61
Quote:
Originally Posted by JEEPFELLER View Post
You don't need anything special with knobs or buttons----plain Jane works fine. trigger is all you need.

Sometimes I'll use my Grandpa's timing light from the '60s, the one's with all of the extra bells and whistles are just that much more confusing to use.

I see these at yard sales and in pawn shops dirt cheap!

Without a way to check/ set stuff, your Jeep may run and run decent, you probably won't really get full potential out of it.

----JEEPFELLER
Roger. Thank you, Sir. I'll be on the lookout for one of those kits. There's a couple decent looking sets on ebay.
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