Big Window Carb Trouble

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drock2

drock2

Joined
May 9, 2008
Threads
33
Messages
223
Location
Rochester, MI
Turning to the experts here for help. I've been struggling with the carb adjustment on the '64.

I started this past spring with a rebuild. Found the correct kit online and spent a good deal of time cleaning it up. I followed the rebuild instructions in the engine repair manual so I don't think I missed anything.

The issue appears to be the float. No matter how I try to adjusted it I can't keep it from flooding. It was to a point where I got it to idle and was able to drive around the block a few times, last time around though it started to run rough. When I stopped and opened the hood, sure enough the bowl was full to the brim.

Here is picture of the carb before I cleaned it up and a quick vid of it idling after the rebuild. Appreciate the help, thanks guys!

[URL="http://i184.photobucket.com/albums/x283/drock301/ef757e3b-391c-4fd4-a3b2-16414879a9ce_zps3a700a1e.jpg"][/URL]

http://s184.photobucket.com/user/dr...2A-3250-0000050F855D54B2_zps3b522297.mp4.html
 
Float looks good to me - not crushed, no visible cracks or holes. I also took a pic of the needle valves (new on left, old on right). They look identical...maybe the new spring is slightly longer?

2EDFD46B-47FF-4FA0-849D-33A4525EECB0-1556-000001F0B9FA9C51_zpse2fbe57c.jpg


4E4F5139-F21E-4EDD-8207-75C4E7CE7493-1556-000001F0C2B11B82_zps187a8608.jpg


FA98D616-E9DC-4AE2-93C1-B755D9560AB0-1556-000001F0CCC3EF64_zpsef66f986.jpg
 
That float does look good. Shake it while holding it close to your ear...hear any fluid in it? A longer spring would help the needle valve close better, to my thinking, but, maybe try putting the old pieces back in it, see if that makes any difference.
 
Nomis said:
Are you still running the OE mechanical fuel pump or an aftermarket electric? An electric pump with excessive pressure may be overcoming the the inlet valve.
Click to expand...

Just put a new Kyosan mechanical pump in.

Pighead said:
That float does look good. Shake it while holding it close to your ear...hear any fluid in it? A longer spring would help the needle valve close better, to my thinking, but, maybe try putting the old pieces back in it, see if that makes any difference.
Click to expand...

Tried the shake test, didn't hear anything. I'll try the old need valve and spring, maybe adjust the center tab on the float more and see what happens.
 
Pin_Head said:
Usually shaking the float is good enough, but the other way to test it is to hold it in a glass of hot water and look for tiny bubbles.
Click to expand...

Hot water test checked out, no bubbles. I'm confident the float is good.

nuclearlemon said:
just send it to us and get a new trollhole carb:D
Click to expand...

I've put way too much time in it to give up now! :p

...and I think I've final made some progress. Messed with the float adjustment more today. She made it around the neighborhood a record number of times, without incident. Fuel level still looked good when I pulled her in the garage! If the weather is nice tomorrow, I'll test it out again.

There are a few other things I've noticed and have questions about:

Is it normal for the fuel level in the bowl to drop while sitting in the garage, after a few days?

If it idles best with the choke closed slightly, is the throttle/idle adjustment off?
 
Fuel level dropping "some" after a few days is normal. Emptying is not, and indicative of a leak somewhere.

If it idles best with the choke closed a bit, it's idling a bit lean and I would back out on the idle mixture screw-assuming that you have the idle speed set to spec.
 
Resurrecting an old thread...same carb but discovered a new issue. After an unsuccessful attempt to start the truck I removed the carb and found a puddle of fuel in the intake. Throttle was never depressed...would that mean something is wrong with the "low speed" side? Where should I focus my attention? I've taken the carb apart multiple times to confirm all the passages and valves are clear. Thanks for all the help!
 
Sounds like the mysterious fuel creeping up and over the bowl by surface tension nto the idle circuit and dripping into the manifold. It is related to the increased polarity of the new "oxygenated" ethanol containing fuel. Old school fuel doesn't do it.
 
Last edited:
Pin_Head said:
Sounds like the mysterious fuel creeping up and over the bowl by surface tension nto the idle circuit and dripping into the manifold. It is related to the increased polarity of the new "oxygenated" ethanol containing fuel. Old school fuel doesn't do it.
Click to expand...

Thanks Pin Head...Would you suggest I try to find E0? Quick look on the web doesn't show much availability in my area. I was able to run the truck previously on E10, with limited success...guess that was just dumb luck.

Looked in the 25 section thread and didn't see any mention...Is this standard practice for everyone running the big window carbs?
 
I don't really know if it is due to the fuel, but I have read that a lot of carburetors have this problem and that it is related to E10, E15 fuel. It makes sense because it is for sure creeping up and over the bowl by surface tension and out the idle port.

It would be nice if you could find some E0 or aviation gas and do the experiment.
 
FJ40Jim said:
Don't assume.
Fuel in the mani is typical. Fuel wetting the plugs is bad. Fuel puddled in the low spot of the mani (that's why its there) is NBD.
Click to expand...
Couldn't have said it more succinctly. RFG is hard on old carbs, and harder on old carbs attached to old motors with less than optimal vacuum.

Will it fire with ether?
 
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