Problem with Rebuilt Carburetor

I see, so when you were holding the caliper in the photo it was set at 5/8” and you were comparing it to the actual fuel level in the tube, correct? I was confused by the photo as well because it’s probably just the angle making it look like the fuel level is actually higher than the caliper. You said the air screw is at 1-1/2 turns out. Did you try adjusting that at all? Given the fact that you were fouling plugs, I would assume that you’d want to try backing it out more to lean the mixture. As stated above, the GAV affects the idle too so I’m of the opinion that the air screw should be adjusted for the best idle with the GAV set to driving position. It always made me wonder why the manuals tell you to drop the idle low enough so that the GAV has no effect on the idle, set the air screw, then mess the whole thing up by opening the GAV again.
 
When I first got my Cabriolet the idle was very erratic, would stall when you came to a stop unless pulling down on throttle level and dripped gas unless fuel was turned off. At some point a Model B Zenith carburetor was installed which I now like. My go to for all my carburetor info has been Renner's Corner. The float level really effects these carburetors, I bought the carburetor fuel level setting gauge part #B-9599-Z from Renner's and built a stand to mount the carburetor on using an old garden tiller gas tank to get the float bowl fuel level spot on. Renner's also machined the carburetor body to allow the use of an air breather. I have now had the carburetor off and on several times, enlarged the intake to match the larger model B throat, installed a missing float chamber baffle, replaced all the jets and it now purrs like a Model A should, no leaks no sputtering at stop lights. If you really want to transform your A switch your cylinder head to a higher compression 6:1 head. Not only does my A now have more power, I get about twice the gas mileage than before.
 
SHEW, I apologize for any grief I might have caused in my former posts. I was merely trying to suggest that, as well as soliciting suggestions from Fordbarners, it might be to your advantage to call the carburetor rebuilder you used since he has a good knowledge of your carburetor. Your last statement that you're disassembly of the carburetor probably voided any warranty is very telling. You may be right about that void. But, if you had called the rebuilder and HE had told you to disassemble the carb as part of the diagnosis process, the warranty might possibly NOT be void.

I am not, by any means, negating any of the many valid suggestions made here. I'm just suggesting the rebuilder might be a worthy addition to your diagnosing the problem.

Again, if I "leaned into it" a little too harshly or offended you or anyone else, I'm sorry. Good luck moving forward with this. Bob
 
bobbader said:
SHEW, I apologize for any grief I might have caused in my former posts. I was merely trying to suggest that, as well as soliciting suggestions from Fordbarners, it might be to your advantage to call the carburetor rebuilder you used since he has a good knowledge of your carburetor. Your last statement that you're disassembly of the carburetor probably voided any warranty is very telling. You may be right about that void. But, if you had called the rebuilder and HE had told you to disassemble the carb as part of the diagnosis process, the warranty might possibly NOT be void.

I am not, by any means, negating any of the many valid suggestions made here. I'm just suggesting the rebuilder might be a worthy addition to your diagnosing the problem.

Again, if I "leaned into it" a little too harshly or offended you or anyone else, I'm sorry. Good luck moving forward with this. Bob
Click to expand...


We’re good, Bob. No hard feelings here. I sent you a PM.


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Brentwood Bob said:
The gav adjustment, the knob on the end of the choke rod, affects the idle. As the motor warms up, the adjustment changes. I think the owners manual goes thru the starting procedure. Dirty fuel is a common enough problem for me. I have had several returns (rebuilts) with this issue.
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The GAV on the original carburetor never did much. I could never see any perceivable difference, regardless of the setting. I haven’t seen much difference in changing the GAV setting on the rebuilt carburetor either.


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Thodge said:
I see, so when you were holding the caliper in the photo it was set at 5/8” and you were comparing it to the actual fuel level in the tube, correct? I was confused by the photo as well because it’s probably just the angle making it look like the fuel level is actually higher than the caliper. You said the air screw is at 1-1/2 turns out. Did you try adjusting that at all? Given the fact that you were fouling plugs, I would assume that you’d want to try backing it out more to lean the mixture. As stated above, the GAV affects the idle too so I’m of the opinion that the air screw should be adjusted for the best idle with the GAV set to driving position. It always made me wonder why the manuals tell you to drop the idle low enough so that the GAV has no effect on the idle, set the air screw, then mess the whole thing up by opening the GAV again.
Click to expand...


I worked on this some more today. The old carburetor works fine (except for the fuel leak). I ordered a gauge from Renner’s Corner today. The gauge I have is difficult to use. So, I plan to try this again in a few days.

Oh, to answer your question, yes, I tried adjusting the idle mixture screw, lots of times. With a vacuum gauge, without a vacuum gauge. THANK YOU for your feedback back. Good Lord willing, I’ll eventually get this right.


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rich40701 said:
When I first got my Cabriolet the idle was very erratic, would stall when you came to a stop unless pulling down on throttle level and dripped gas unless fuel was turned off. At some point a Model B Zenith carburetor was installed which I now like. My go to for all my carburetor info has been Renner's Corner. The float level really effects these carburetors, I bought the carburetor fuel level setting gauge part #B-9599-Z from Renner's and built a stand to mount the carburetor on using an old garden tiller gas tank to get the float bowl fuel level spot on. Renner's also machined the carburetor body to allow the use of an air breather. I have now had the carburetor off and on several times, enlarged the intake to match the larger model B throat, installed a missing float chamber baffle, replaced all the jets and it now purrs like a Model A should, no leaks no sputtering at stop lights. If you really want to transform your A switch your cylinder head to a higher compression 6:1 head. Not only does my A now have more power, I get about twice the gas mileage than before.
Click to expand...


Thanks for the “plug” for Renner’s Corner. I placed an order today for some spare parts that I should have purchased a while back anyway.


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I finally got some time this weekend to work on the rebuilt carburetor again. I bought new flow tested jets from Renner's Corner, disassembled the carburetor again, sprayed carburetor cleaner through the passages, blew out the passages with a rubber tipped blow gun (as recommended by Renner) replaced the old jets with the Renner jets, reassembled the carburetor, set the idle mixture screw to 1-1/2 turns open, and the car started right up. I took it for a test drive, and it can climb a hill, and there is no backfiring. The rebuilt carburetor seems to run as well as the original carburetor. Thank the Lord, I think I'm close to finished on this project. Thanks, everyone, for your help. I'm no expert, but I have learned a lot about carburetors.
 
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