I installed a Carter YF 3211s carb from a 235 on my 261 about a year ago. Love the way it runs but am concerned that the spark plugs still look brand new ( too lean? ). Can any changes be made to the carb or should I even be concerned about it?
I don't think you should be concerned about that, Dave...especially if it starts well and runs well. You might see if any of the vehicle inspection stations around you still have the tailpipe sniffer they used to use for air quality checks. Most of these were not much more than an air/fuel ratio reader connected to a computer. They'd be able to tell if you were running too lean or not. But honestly I doubt you are. Unleaded ethanol fuel by nature does better with a slightly richer mix, but usually about 10% richer will take care of it.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
If I remember what Carbking taught us (if I wasn't sleeping in class again), a smaller carburetor on a bigger engine runs rich? More vacuum from bigger pistons sucking all that gas down the hole....I guess. Okay, fun time is over.
I'm running a YF-2100 (for 235) on my 261 mainly until I finish testing some other carburetors. Stock ignition system. Non-ethanol gas. Compared to the Rochester B model made for the 261, the YF-2100 starts up 10X better after the truck has sat for a week. Idles better, accelerates (initially better) and I just like it. Last time I looked at the spark plugs they looked good. However, it runs out of legs at higher speeds/rpms/load. Seat of the pants feel not verified with testing.
I think the excellent Carter metering system makes up for the difference in typical normal driving. What it can't compensate for is when a bigger venturi size is required to get the A/F mixture correct on the top end.
"Adding CFM to a truck will only help at engine speeds you don't want to use." "I found there was nothing to gain beyond 400 CFM."
The Carter 3211s, designed for the smaller 235 CID, probably will lose about 400~500 RPM at the top of the RPM range on a 261.
Jon.
Good carburetion is fuelish hot air The most expensive carburetor is the wrong one you attempt to modify. If you truly believe "one size fits all," try walking a mile in your spouse's shoes! The Carburetor Shop
Don't have any vehicle emissions stations in my area. Not required where I live. I am running a stock ignition system with points and condenser after a bout with Pertronix. I thought also that a smaller carb should run rich. Never overheats. I always use 91 octane ethanol free gas. This starts up so much easier also when cold and accelerates very well. Not too concerned about losing 400-500 at top end. Never need that. Extremely happy with the performance. Was just wondering about the lean looking plugs. Thanks for all the input. Dave
Dave, thanks for the information. If you and I both loaded our truck beds and headed up a mountain, we may be able to tell a difference. I don't know about you but my bed has as good paint job.
While Carbking is here, I have a nagging concern about the automatic choke design that Carter uses on the YF-3211s and other models. The reason for the question is for longevity of the carburetor.
The heat needed to affect the choke coil is currently pulled off/from the manifold choke stove, through a sleeve covered inlet tube, by a slight amount of vacuum supplied from the internal carburetor passage, through the choke housing. Keeping the choke housing clean inside is a problem? I've never had one open for inspection hence the question. I prefer a manual choke but sometimes the manual carburetors are simply no longer available to purchase.
I've notice that, on the Carter WA-1 carburetors, a similar design and uses a fine mesh screen to block contaminates but the screen eventually becomes blinded (tiny cast iron flakes, dust, oil mist, road grime) and the choke fails to work properly. Wouldn't a better design have a filtered inlet (air cleaner maybe) and run it through a coiled tube around/near the manifold and on to the carburetor choke housing?
"Adding CFM to a truck will only help at engine speeds you don't want to use." "I found there was nothing to gain beyond 400 CFM."
Very few factory automatic choke assemblies have filtered air. But yes, a very few did. One that didn't was Cadillac.
Jon.
Good carburetion is fuelish hot air The most expensive carburetor is the wrong one you attempt to modify. If you truly believe "one size fits all," try walking a mile in your spouse's shoes! The Carburetor Shop
However if you want filtered air (more or less...at least as filtered as what enters the engine), then wrap the copper line leading from the automatic choke around the exhaust manifold and then up and into the air cleaner...in the same fashion as the pcv tube terminates. That's at least one way to do it and probably the simplest.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
I did convert mine to manual choke which I do like. Engine has plenty of torque and power. We pull a vintage camper that is about 2000 lbs loaded and it does well.
Dave, thanks for the information. If you and I both loaded our truck beds and headed up a mountain, we may be able to tell a difference. I don't know about you but my bed has as good paint job.
While Carbking is here, I have a nagging concern about the automatic choke design that Carter uses on the YF-3211s and other models. The reason for the question is for longevity of the carburetor.
The heat needed to affect the choke coil is currently pulled off/from the manifold choke stove, through a sleeve covered inlet tube, by a slight amount of vacuum supplied from the internal carburetor passage, through the choke housing. Keeping the choke housing clean inside is a problem? I've never had one open for inspection hence the question. I prefer a manual choke but sometimes the manual carburetors are simply no longer available to purchase.
I've notice that, on the Carter WA-1 carburetors, a similar design and uses a fine mesh screen to block contaminates but the screen eventually becomes blinded (tiny cast iron flakes, dust, oil mist, road grime) and the choke fails to work properly. Wouldn't a better design have a filtered inlet (air cleaner maybe) and run it through a coiled tube around/near the manifold and on to the carburetor choke housing?
Do a websearch for “sintered brass filter” or “sintered bronze filter.” Should be able to find something you could adapt into or onto the tube that feeds the choke. I don’t know how it might affect the hot air transfer.
Memory (sometimes off a year or two) states that about 1961, Pontiac started actually filtering the air to the automatic choke. This was accomplished by drilling a hole (1/4 inch maybe?) into the air intake below the air cleaner and above the choke butterfly. A brass tube was pressed into the hole. A piece of neoprene tubing about 1 inch long (vibration joint) then attached the brass tube in the air horn to a tube that ran down to a plate on top of the intake. Removing the plate would reveal a "U-tube" that was inserted into the cross-over heat passage (V-8). The other end of the U-tube went back through the plate, and was then attached to the choke housing.
For a real picture instead of the word picture above, Google Pontiac internal choke tube
Jerry and I agree to disagree on my following statement; but I personally convert ALL automatic chokes to manual on my personal vehicles. To be fair, my vehicles are not stock, thus the auto choke is not programmed for my engines.
Jon
Good carburetion is fuelish hot air The most expensive carburetor is the wrong one you attempt to modify. If you truly believe "one size fits all," try walking a mile in your spouse's shoes! The Carburetor Shop
The Carter choke stove was a different design from the aftermarket stoves, but not really that much. They all worked the same, but the Carter stove looked better and showed more thought. A picture of a brand new one is attached. The second image shows the hole for the choke tube. Many people when they would install these (be they any choke stove) would take a moment and flare the tube so it wouldn't come out, and the tube could have been copper (most common) or aluminum. They weren't really concerned about filtered air, but in a moment I'll tell you how that can be accomplished. This tube was covered with an asbestos cloth (image also attached). As I've said on this forum a few times, you could make your own completely filtered stove by simply wrapping the copper tubing around a part of your manifold, connecting one end to the carburetor and running the other end up and into your air filter just as the PCV tube is placed. In case you're curious about Carter's instructions for the choke stove, they're attached. This instruction sheet removed from a brand new 3211s.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
