Unusual Carburator vacuum leak

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rmel
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Joined: Sun Sep 25, 2011 12:19 pm
Location: Woodside, CA
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Unusual Carburator vacuum leak

Post by rmel »

Well this is something you would not expect to experience.

A plug fell out of the top cover plate of my forward Carb, PIX attached.

For some time, I have suspect a vacuum leak, just based on how she
started and ran until hot but could never point point any issue.

Then, on a 200 mile dive to a trail head she started to run like crap.
Low power and my AFR meter was reading a very rich condition.

Stopped at a buddies house and started to tear into the problem (Jim L
gave me some clues to track down). Hmmm, Spark plugs 1 and 2 showed
signs of poor ignition -- so, moved up to the carbs and right away noticed
a plug was missing, right next to the accelerator pump reservoir. Pulled
the jets and they were completely plugged up. Soooo, that vacuum leak
was also pulling dirty air into the accelerator reservoir. The net result
was plugged jets and fuel leaking into throttle-plates that was not in a
vapor.

Plugged the hole with a grommet and off she ran.
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IMG_2720.jpg (722.98 KiB) Viewed 204 times
Puller: 71' 710K 2.7L EFI aka Mozo
Follower: Sankey MK 3, 3/4 Tonne
Rescue Pinz: 73' 712M

Driver: Ron // KO0Q
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4x4Pinz
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Joined: Sat Oct 24, 2009 6:17 pm
Location: arizona

Re: Unusual Carburator vacuum leak

Post by 4x4Pinz »

I lost one on mine some time ago. Found a suitable plug and all was good to go. Later when doing some work I found the original plug on the engine, how lucky
ChickenPinz
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Re: Unusual Carburator vacuum leak

Post by ChickenPinz »

rmel wrote: Thu Jul 28, 2022 10:43 am Low power and my AFR meter was reading a very rich condition.
Which AFR meter did you use and how did you connect it into the engine? Do you use two sensors, or just one?
710K
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rmel
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Posts: 1271
Joined: Sun Sep 25, 2011 12:19 pm
Location: Woodside, CA
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Re: Unusual Carburator vacuum leak

Post by rmel »

Wideband O2 sensor ala PLX Devices with Bosch sensor.
Bung welded to header that picks up cylinder #1 & #4.

Also have a Porch/Bosch head temp sensor in head #2.
Puller: 71' 710K 2.7L EFI aka Mozo
Follower: Sankey MK 3, 3/4 Tonne
Rescue Pinz: 73' 712M

Driver: Ron // KO0Q
Pinzengauer
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Joined: Sat Apr 06, 2019 12:53 am

Re: Unusual Carburator vacuum leak

Post by Pinzengauer »

Had that happen twice, once on each carb, first time was in the middle of the desert of Arizona. Tin can and JB weld fixed er up!
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