Is this a stock carburetor configuration?
- Thread starter shew01
- Start date
Marshall V. Daut
Well-known member
Yes, although the fuel inlet/filter bulb on the side should be straight up and down, not cocked at an angle. The fuel line looks a little wonky, though/
Marshall
Marshall
nkaminar
Well-known member
I concur with Marshall. In the latest issue of the Restorer Magazine, May/June 2025 issue, in the Technical Q&A section, page 4, there was a question about whether this "side bowl" needed a gasket. The carburetor was off a late 1931 car. If you take the side bowl off you will find a screen inside.
shew01
Well-known member
I’d like to order a fuel line for it. Is this the correct fuel line?
https://www.snydersantiqueauto.com/product.htm?pid=979356&cat=41707
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https://www.snydersantiqueauto.com/product.htm?pid=979356&cat=41707
Sent from my iPhone using Tapatalk
Marshall V. Daut
Well-known member
1. Yes, that's the correct fuel line for late '31 indented firewall cars with side bowl Zenith carbs (Holley-2 or Holley-3)
2. 10 MPG is unacceptable. I suspect a previous owner slapped in a carburetor "rebuild kit" from one of the vendors. These kits usually have incorrect jets sizes with improper flow rates that will affect gas mileage and performance. Before panicking, order a set of flow-tested jets from Renner's Corner and install them. They will for sure help your carb operate more efficiently. Order the special tool to help remove the longer jets.
3. No, the angle of the sediment bowl on the side of the carb will not affect mileage or performance, unless the filter is clogged or the fuel line is pinched, limiting fuel intake to the carb.
Marshall
2. 10 MPG is unacceptable. I suspect a previous owner slapped in a carburetor "rebuild kit" from one of the vendors. These kits usually have incorrect jets sizes with improper flow rates that will affect gas mileage and performance. Before panicking, order a set of flow-tested jets from Renner's Corner and install them. They will for sure help your carb operate more efficiently. Order the special tool to help remove the longer jets.
3. No, the angle of the sediment bowl on the side of the carb will not affect mileage or performance, unless the filter is clogged or the fuel line is pinched, limiting fuel intake to the carb.
Marshall
Marshall V. Daut
Well-known member
4. Yes, the float is most likely in need of adjustment if the engine stalls upon quick stops, either higher or lower. Experiment with the float height to match your engine's sweet spots.
Marshall
Marshall
Bob Bidonde
Well-known member
The side bowl on your carburetor is a sediment trap, and it is full of gas when the shutoff valve is open. Thus if you occasionally drain the sediment out, the side filter bowl has no effect on the engine's performance regardless of its angle.
Ed in Maine
Well-known member
Hello Shew01, you are lucky to have that 1931 side bowl carburetor used with the indented firewall. I am finishing a restoration on a late 31 Cabriolet and don't have this carburetor. I would like to have one but I don't want to pay up to $300-400 dollars to get it when I have several of the other Zenith designs! I do have a side bowl filter however and tried to mount it on the other style of Zenith carburetors and it won't fit. The side bowl filter casting interferes with the other style Zenith. Is this the reason why your side bowl filter is mounted in a tilted position?
I also note that you have an exhaust leak at the manifold connecction. Ed
I also note that you have an exhaust leak at the manifold connecction. Ed
nkaminar
Well-known member
Ed was very observant to notice the black carbon at the connection between the manifold and the exhaust pipe. Way to go ED.
There are a couple thing to do to try and fix the leak. One is to make sure the flange on the exhaust pipe is not bent. You can probably tell where it was leaking and maybe use a body hammer to make it correct. Another thing is to use a high temperature RTV gasket sealer.
When you tighten the clamp, wiggle the exhaust pipe a little to make sure it is seated correctly against the exhaust manifold.
There are a couple thing to do to try and fix the leak. One is to make sure the flange on the exhaust pipe is not bent. You can probably tell where it was leaking and maybe use a body hammer to make it correct. Another thing is to use a high temperature RTV gasket sealer.
When you tighten the clamp, wiggle the exhaust pipe a little to make sure it is seated correctly against the exhaust manifold.
shew01
Well-known member
Thanks, Marshall. I ordered jets from Renner’s. I didn’t know there was a special tool to remove the long jets. Are there any other oddities with this carburetor?
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shew01
Well-known member
Ed, carburetors are a weak spot for me. Where do you see the leak. I think I’ve heard a noise that could be a leak, but I’m not sure how to track it down.
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shew01
Well-known member
Marshall V. Daut
Well-known member
In addition to nkaminar's advice, make sure when you re-install the clamp that you orient it correctly with the wider portion on the underneath side. Some of the poorer off-shore repo clamps from the 1970's and 1980's could fit either way, but didn't do a good job holding the muffler pipe and exhaust manifold together. Yours is o.k. with its wider lower portion present. Your clamp is oriented correctly in the first photo. Just make a mental note when you remove the clamp to tap the muffler's flange against the exhaust manifold's flange that you put the clamp back on as you see it now.
Once you have sealed up the muffler pipe to exhaust manifold, if you hear a ticking sound while the engine is running, there is also an exhaust manifold leak, usually emanating from the back exhaust port, #6 in line. As we all know from sad and expensive experience, that part of the manifold tends to droop from the heat of manifold and the weight of the muffler pulling down on it. This will create a gap in port #6 from which exhaust gases escape and cause the ticking sound as each cylinder fires. The only true cure is to replace the exhaust manifold with a NEW one from any of the vendors. Look for black splotches of carbon around the back of the exhaust manifold. That's a telltale sign that at the very least a gasket has blown out or at worst, the manifold is drooping. $$$$$$$
On the other hand, a whistling sound usually comes from a leaking intake manifold sucking in air. Learn to identify the Model A's many sounds when diagnosing problems and it'll make your life repairing these old beasts easier.
.
Marshall
Once you have sealed up the muffler pipe to exhaust manifold, if you hear a ticking sound while the engine is running, there is also an exhaust manifold leak, usually emanating from the back exhaust port, #6 in line. As we all know from sad and expensive experience, that part of the manifold tends to droop from the heat of manifold and the weight of the muffler pulling down on it. This will create a gap in port #6 from which exhaust gases escape and cause the ticking sound as each cylinder fires. The only true cure is to replace the exhaust manifold with a NEW one from any of the vendors. Look for black splotches of carbon around the back of the exhaust manifold. That's a telltale sign that at the very least a gasket has blown out or at worst, the manifold is drooping. $$$$$$$
On the other hand, a whistling sound usually comes from a leaking intake manifold sucking in air. Learn to identify the Model A's many sounds when diagnosing problems and it'll make your life repairing these old beasts easier.
. Marshall
Page 560 of the Service Bulletins addresses installing a side bowl filter on a non side bowl carb, says to use two gaskets between side bowl and carb.