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Discussion Starter #1
ORIGNAL PROBLEM: 289 running very rich. pulled carb off and found fuel pulling in the channels surounding the barrel openings on the intake manifold. Lots of hesitation on acceleration

Ok readjusted floats(they were way to high), set timing inaccordance with pony carb recommendations i.e., advanced until it just stops pinging, set carb up with a vacume gage (19 pounds). However when I pulled the carb off I still had fuel pulling in the channel sourounding the barrel openings on the intake manifold.


Additional info:
I notice when i ran the engine without the air horn on the carb to double check float settings that fuel was bubbling at the fuel inlet needle and seats on both the primary and secondary sides. is that normal?

Car runs great however.it still runs rich.......what next?
 

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Help us out a bit....do you mean that fuel is "puddling" (as in little puddles) in the channels adjacent to the manifold bores?

If so, have you pulled the carb off and set it onto a clean dry surface (level) to see if it has internal leaks? I usually use an old coffee can. You could also/instead have a blown power valve.

When you checked the fuel levels, did they appear to hold steady, even in light of the "bubbling"? As the needle and seat is a valve, there will be some flow which looks like bubbling as the needle moves in response to engine vibration and the float. When checking this, it's a good idea to have a fire extinguisher around in case something goes wrong; also, be sure to do such checks outside.

I believe your rich condition and off-idle hesitation are two seperate issues but will know more once you clarify.

Edited to query as to whether the hesitation has completely disappeared now or still exists.....?
 

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Discussion Starter #3
Frst thanks for your help. In answer to your questions:


1. do you mean that fuel is "puddling" (as in little puddles) in the channels adjacent to the manifold bores

Yes..... the channels were filled with fuel.

2 If so, have you pulled the carb off and set it onto a clean dry surface (level) to see if it has internal leaks? I usually use an old coffee can. You could also/instead have a blown power valve.

Today the carb set on my work bench with fuel inside both pri and sec bowls for a few hours....no leakage noted.

3. When you checked the fuel levels, did they appear to hold steady, even in light of the "bubbling

YES..

As far as the hesitation problem is concerned....it went away after the first float adjustment, timming set and carb adjustment with a vac gage. I thought that would fix all my problems. But when I noticed it was still running RICH I removed the carb and found fuel again inside the channels.

How do I check for a blown power valve?

Rich
 

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Take a look at this picture. Do you see the linkage operating the lever on the left? That's the accelerator pump linkage. Look below that area on the bottom of the primary fuel bowl. There should be a cover with 4 screws. Under that is the power valve. I usually test it by removing it and sucking on the diaphragm. A leak is usually obvious. Obviously, a hand vacuum pump with the right adapter works much better *G*.

Everything else sounds OK.....
 

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Discussion Starter #5
Thanks again for the help.

I pulled out the power valve and noticed the following:

1. when i reomved the cover plat fuel came out. It that normal?


2. when I sucked on the diaphragm i heard air being sucked through. However if I put my fingers over the little holes just under the threads on the front side I got a tight seal.
 

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Replace power valve.

Report on observed results to engine operation. 4100's are simple, reliable carbs. My instincts are this should do it.

IIRC, there were certain batches of power valves which gave problems. One of my customers turned me on to a replacement his company (PG&E) had found to fix the problem. If I can find one out in the shop, I'll post the part number. As this happened years ago, all replacements likely are fine now. I haven't had any problems with the one on the D-coder.

Get back to us if you need further assistance.
 
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