VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc 216 Carburetor Problem

I have a 1940 1/2 ton pickup that is stock except that it has a 1948 Chev passenger car cylinder block with a 1940 head and a Carter W-1 carburetor. The engine runs great, but once it is fully warmed up, as after a few miles on the highway, when I shut it down for 10 or 15 minutes to go into a store, for instance, when I try to re-start, the engine is flooded and takes a great deal of extra cranking to draw in enough air to dilute the gas that has spilled into the manifold while sitting.

It seems to me that perhaps the float valve is leaking, allowing the level in the float chamber to get too high. When running, it doesn't seem to matter, but when shut down, the high level results in gas overflowing the "slip nozzle" into the carburetor throat. I've set the float level slightly lower than called for and checked the float valve by blowing into the carburetor gas inlet. The valve seems to shut tight.

Is there another common problem I am overlooking that might cause my flooding problem?

Mark Yeamans
VCCA #35724

Press the accelerator pedal slowly all the way down to the floor. Now try to start the engine and see if that makes a difference.

Another way to look at is that the fuel is perking out of the carb while sitting and your excessive cranking is providing fuel to refill the carb. If the starter is in good condition and you have proper sized cables with a strong battery then the fuel is the problem. Personally I have found that after the car sits and it is time to restart I depress the gas pedal 1/2 way then try to start. If fuel evaporation is the problem depressing the pedal shoots fresh fuel into the manifold and allows fresh air in as well. You can do this about twice before flooding the engine and then you must floor the pedal and hold it there while cranking to clean out the cylinders.

Check the needle in the float circuit. If it is a Viton tipped needle throw it away and replace with a metal needle. Install a matching seat for the metal needle as well.

Dog is a Viton tipped needle one that has a red-sh tip or what dose it look like

The Viton needle has a rubber tip.

OK THANK YOU

Mark,
I assume that the heat riser is not stuck in the heat position.
Next time disconnect the gas line as soon as you pull into your drive way and then watch if the fuel spills over. If it does it cased by expansion of the gas. If not a new needle and seat may be in order.

This certainly seems to be a common malady with the W-1’s on the 216’s. This is discussed over at the Stovebolt every month or so which tells me it’s not at all unusual.

I pride myself as being a meticulous mechanic and spend way to much time when I rebuild a carb. I even go to the extremes of removing the plugs and making new lead or copper plugs depending on what carburetor I’m rebuilding. When I rebuilt my first carb back in the 50s these plugs were supplied with the rebuilding kits. Me pop was an old school mechanic and had served a regular apprenticeship in the 20’s and he taught me that to do a thorough cleaning ya needed to get at all the passages, so we pulled the plugs on all the carbs we rebuilt. I rebuilt several W-1’s this year and they all suffer from the same problem you describe.

I’ve talked with Jon Hardgrove who owns the Carburetor Shop over in MO and this seems to be a common complaint with him also. His suggestion for starting is the method that I use and it does work every time for me.
If the truck has been sitting for more than 15 or 20 minutes I don’t touch the throttle, that, only pumps more fuel into the engine. I depress the starter with the throttle at idle and it will catch the third or forth time over and then very gently add some throttle. The engine will always clear it self after a few seconds.

I am a firm believer that the percolation problem has always been there with these carbs but the fuels are formulated differently than it was back when they designed these carbs and it’s worse now. I’m experimenting with dropping the float level to cope with the percolation, I’ve already dropped it about 3/32” in a W-1 that I’m running now and it performs just fine and supply plenty of fuel at 60mph with a 4.10 gear but the hot start problem is still there.

Another typical problem I’ve run into with the W-1’s and the Rochester’s is that they both tend to run lean. I have three W-1 684’s and a handful of Rochester B’s that have all been meticulously rebuilt and adjusted right to the spec and they all run just about as perfect as you would expect as long as the choke is pulled out just a tad, around a 1/4” to 3/8”. That gives me a nice smooth even pull all the way up through the gears with no hesitation. Now mind you, this is not an isolated case, this is with three different engines in there different trucks with three different rebuilt carbs. And before you say it, yes, the accelerator pumps are operating just as they should be and the throttle connector rods have no slop and have been adjusted with the proper gauge and the insulator blocks are NOS Bakelite and the heat risers are all opperating properly.

So, one more time, I really think that the fuel today has something to do with the not so perfect rather finicky performance of these older carbs.

Denny Graham
Sandwich, IL

"don't touch the throttle" is impossible as 1938 and up vehicles with the floor mounted starter as they have a feature that automaticly opens the throttle about 1/3 when the pedal is depressed.
I will say I have never had this problem with my W-1 equipped cars. We have had ethanol here for over 15 years + have traveled all over the country using many mixtures of gas.....am I just lucky or what?

Thanks for the advice, folks.

Gene--my manifold heat valve is stuck, probably in the "heat on" position. I guess it's probably time to take the manifold apart and fix it.

Denny--I noticed my engine seems to run a little lean and even when warmed up, on accelerating from low RPM, sometimes the engine power is somewhat "tentative". If I pull the choke out slightly and momentarily, there is a noticeable increase in power. Other than that, the engine seems to run strong and I get about 15 to 17 mpg at 50 mph, which drops to 13-15 at 55 mph. It's possible that the weak acceleration is due to the stuck manifold heat valve--the Chevrolet shop manual indicates that a manifold heat valve stuck in the "heat on" position may result in "lazy" acceleration.

I think my carburetor flooding problem may be due to percolation. Fixing my manifold heat valve and experimenting with an even lower float level might improve the condition.

Mark

Well Gene, I guess as the song says, “You’ve got the, Magic Touch”. Not trying to be a smart [bleeped] Gene, I’m just poking some fun at ya buddy, you know how much I respect your opinions.

But the fact remains that these complaints are just so common that I’ll bet a month doesn’t go by that I don’t here someone asking about them and even the carburetor guys don’t have any concrete answers.

The W-1 and Rochester ”˜B’ carbs are pretty basic carburetors and if you pay special attention to making sure that all the passages are clear and completely open, and that nothing is worn like a connection rod or jet and that the few adjustments and alignment points are attended to, there is no reason that they shouldn’t perform as well today as yesterday. So the only common denominator and the only logical explanation I can think of is fuel. If you or any one else knows of some sort of special trick to keep them from percolating after they are shut down I sure would like to here about it. I would also like to hear a logical explanation of why when you step down hard on the throttle that every one that I’ve seen has a little stumble and goes on it nose for a second, even when the accelerator pump is working properly and newly installed.

And I would also very much like to take a ride in one that is supposed to run smoothly and accelerates with no stumble or hesitation and one that will start first turn over when parked hot.

I’ve seen a lot of guys over the years that will not admit after spending months or years rebuilding their pride and joy, that the performance is anything less than perfect.
Let me say this, that I’m always open for suggestions, believe me, I’ve tried dozens and dozens of them no matter how hair brained they were. And a day doesn’t go by that I don’t learn something new, so teach me something!

And Mark, Gene’s the expert here, so listen to what he has to say. I’m just one of the new guys with my own opinions based on some plain old common sense. But yes, in my opinion you can expect less than optimum performance if the heat riser butterfly is stuck. Once the engine is warmed to operating temperature it should be diverting the gases away from the bottom of the intake. Lets not forget that a whole bunch of GM engineers spent a whole bunch of time designing these engines. To get the best performance out of them I’m a firm believer that every thing should be just as it was when it rolled off the production line.
Denny Graham
Sandwich, IL

Denny,
No problem, no offense.
The point I was trying to make is that it is not a "design problem" with the carburetor but rather some mechanical problem.

At to the "stumble" problem with your engine. You have mentioned that the your engine is worn and tired. You would be surprised how much better it would run with good compression.

I don't know a lot about W1 carbs, but the couple that I have overhauled according to the Chevrolet Shop manual and the instructions that came with the kit, it was not that much of a job, also I never have had a Rochester B carb that needed any choke after a short period of warm up, when the heat rizer flapper valve was working . The Rochester BCs that I have overhauled always used too much choke for our area. There are so many different jets that there should be one that is right for every area. To make the carbs run with close to the right mixture usually a Rochester one barrel suffers from too little of air in the mixture everything else being correct. I also have to disagree with JYD about all Vitron Needle valves being bad from the git-go. I use them for everything from a 5 HP B&S up thru a Chevrolet Q-jet with no problems. Of course in a lifetime of rebuilding carbs as long as JYD has been doing it, he probably has found several Vitron needle valves that leak or stick. I had a carb on a Dixon ZTR mower that had the body of the needle valve (all brass) glued in with new gas varnish, and I had to use needle nose pliers to pull it out.
Different strokes for different folks...

It is true that W-1 carburetors have a tendency to percolate if everything is not right on the carb and engine. A sticking manifold heat valve is a major cause of after fueling or percolation. The addition of the insulator between carb and manifold plus internal changes minimized the problem beginning with the late '32s went a long way toward the problem. By the 1934s it was a minor problem if everything is right.

Modern gas does not help any of the older cars. The blends have a greater percentage of lower boiling compounds which makes several problems worse. Ethanol is only part of the problem. There are hundreds of gasoline blends supplied across the US. Winter blends have much more of the lower boiling compounds so any percolation will be worse if one of those is used.

I suppose that I should just drop this and fade back into the corner, but, I just taint gonna learn anything if I do that, am I? And after all, isn't that the reason most of us join into these forums, to learn or in some cases to teach. If I knew it all, I wouldn't need anyone’s input or opinion on anything.

So I hear the "term having everything right", now just exactly what does that mean? If all the mechanical adjustments are made according to the factory specs, is that "right"?

If everything starting at the fuel tank all the way up to where the cobs come out is clean inside and out, new or fresh, then is the fuel system “right”?

If the proper intake and exhaust manifolds are in place with new gaskets and a NOS phenolic insulator with a new fiber gasket on both sides and the manifold heat valve is working properly and there are no vacuum leaks and the engine has a steady needle at 20in.hg. at idle, is that “right”?

If the ignition system has all new parts installed like points at .018”, condenser, cap, rotor, copper wires, new AC45’s gapped to .035”, a new coil, a new battery, new 2/0 cables, a distributor that has been totally disassembled, checked for shaft and lobe wear, advance spring tension checked, reassembled with the proper lubrication and adjusted according to the factory sepecs, is that “right”?

Now we are left with the basic engine itself, if the cylinder head has been chemically dipped, Magnafluxed and pressure tested, new hard seats, new guides and valves installed and the surfaces machined flat by a long standing competent automotive machine shop, valves adjusted hot to .007” and .014”, is the “right”?

Ok, we’re getting down to the wire here guys, if the engine has 120lbs compression all the way down the line when warm, uses some oil and has a few minor rattles, slaps and knocks because it has 59,537 miles on it, is that reason enough for it, to be “not right”?

And I say again, I’m really open to any solutions, suggestions, as to what you might think is not “right” in this restoration process and am willing to try any of your suggestions.
But remember what I said earlier, I am in close personal contact with three early original 50’s 216 powered trucks and they all seem to suffer from the same minor symptoms.

Denny Graham
Sandwich, IL

Since there are some vehicles that don't appear to suffer from the peculation problem there must be a reason. I am not smart enough to know what it is. I suspect that a major reason for different performance is fuel. The 100+ gasoline blends across the country is highly suspect.

I have rebuilt less than 100 W-1 carbs so still have things to learn. I have been able to get some of the early '32-33s to run very well. Might just be luck but if so then hope it stays with me.

I had the lean condition and the hesitation from the very start after bringing home the truck. The first thing that came to mind was that the carb needed to be rebuilt with special care paid to the accelerator pump and power piston. After spending a week meticulously going over every section of the ”˜B’, which included making a special fixture I made in my Bridgeport that I used for annealing the castings in the oven to flatten the mating surfaces out. This stopped the weeping around the mating surfaces but to my surprise the stumble was still there. I was bound and determined to keep the truck in its stock configuration, which meant keeping the original low shoulder style air horn Rochester B carburetor. I had found several other early ”˜B’s and did similar rebuilds on them over the summer of 2007, but they too, displayed the same performance oddities.

After hearing Jon Hardgrove aka the carbking from The Carburetor Shop talk up the Carter W-1 and express his dislike for the Rochester ”˜B’, I decided to try a W-1 to see if it performed any better than the Rochesters. I had been keeping my eyes open for the 684 models and had by now acquired a couple of decent candidates. After rebuilding the first one and installing it on my ”˜50 to my surprise it acted exactly the same as the Rochester. That is, it seemed to run lean, had a hesitation and by adding a touch of choke it smoothed right out and you could feel the difference in the pulling power up thru the gears.

Now I was starting to look else where for a problem and re-examined the ignition timing and valve clearances. After spending literally weeks going through the entire ignition system to make sure that it wasn't a timing problem and re-setting the valves several times and still making no change in the performance, I was back thinking about the fuel system.

Feeling that I had eliminated the electrical system and timing and the basic fuel system as the culprits I turned my attention to the fuel it self. Having run dragsters in the 50's on methanol and midgets on straight methanol in the 60's and 70's I was well aware of the greater flow rates needed when running alcohol for fuel. I had this gut feeling that the blended fuels had something to do with the lean mixture symptoms because the original carbs were jetted for straight gasoline. I felt that the alcoholic fuel blends might demand that I move up a step or two with the jets. The most nondestructive way to test this out was to find a non-alcoholic fuel blend, which isn’t easy in Illinois. I settled on Aviation fuel since I live on an airport. The avgas has to be blended to have a higher vapor pressure to prevent vapor lock problems at altitude so alcohol blends are not used.
So I ran about 10 gallons of avgas through the engine and that didn’t make a speck of difference.
Now I wish I could say that I’d found the solution, but I can’t. The percolation? I have no idea how you can stop that. I suppose that I can keep dropping the float level till I begin to starve for fuel at 60mph then bump it back up a 1/32”or so and see if that would stop it but I don’t think it would. It’s still not going to stop the fuel that’s left in the bowl from vaporizing from the residual heat. And I’m still hoping to here from some source a logical explanation of what it is that is not “right” in my method of attack.

And by the way, I am getting writers craps but I'm just trying to be as thorough in my narrative as I am at the workbench.
Denny Graham
Sandwich, IL

As an experiment you may want to enlarge the size of the accelerator jet opening.(jet oan a W-1, opeing on a Roch)
The low cover Rochester carbs. had a stumble problem from new on. Some did and some didn't. We replaced many pumps for that reason. The pump circuit was completely redesigned in 1952 so as to insure is was kept full of fuel at all times.
Did you ever experiment with changing (slightly) the length of the link that hooks to the plunger?
Would also be intresting to see what a Carter YF would do.

See now, that’s the first time I’ve heard anyone mention that GM knew about the stumble or hesitation with the early models of the ”˜B’. I was aware that they changed the accelerator well and discharge stop because when I rebuilt mine it was missing the filter screen and spring clip below the pump. I made a new screen and spring clip to correct this. Also the early ”˜B’ had a pump discharge stop that was a split plug where the later ones used the flat ”˜T’ shaped retainer, which are supplied in all the new kits. The later flat top model ”˜B’s that I have rebuilt did have a few settle changes to the pump area, but I’ve never found any documentation on the evolution of the ”˜B’ or reference to why these changes were made. I did notice a mention of the powerglide carburetor displaying a lean condition in the March 1953 Service Release page 3. The correction is to replace the Main Well and Power Valve support with the one used on the conventional models.
I would like to hear where you found your information Gene and I’ll try to look it up. I’ve been adding a copy of the Chevrolet Service Notes whenever I need to fill in an order from the vendors and may have a complete set one-day. Kieth Hardy also has some of them posted on TOCMP that I’ve printed out.

I’ve shied away from re-drilling the jets for two reasons;
The first and primary is that it’s deviating from the factory design or calibration of the carburetor and many of you claim that your engines run just fine when they are “right” and I’m assuming that part of that “right” is having everything up to factory specs.
Number two is that it’s irreversible unless you have access to new jets to put it back the way it was. The carburetor shops do have new jets for the W-1 and Rochesters, but I can damn near buy a new carburetor for what they want for a jet for one of these vintage carburetors.
For instance, on the W-I’s the little 1/4” dia. clip at the top of the throttle control rod costs me eight bucks, the metering rod retainer spring which is nothing more than 2” of .012”(28.5ga.) spring-temper carbon steel wire bent into a loop was another eight bucks, I can buy a 1/4lb spool of that wire for less then that single spring cost me. A standard rod gauge which is nothing more than a 1/8”x 4”x 1/16” piece of sheet metal cost $30 and then there is always the ten bucks for shipping and handling. Of course all these items are probably a bargain if you don’t have access to the dimensions, tools or skills to make them your self. I think you can see why I haven’t strayed to far from the path in my search for a solution.

No Gene, I have not re-bent the accelerator link on the ”˜B’; I have made the adjustments to the throttle control rid on the W-1, which does affect the performance if is not set properly. I’ve only made the factory adjustments to the carburetors and the only adjustment that I have varied from is the float level, which I have dropped slightly in the interest of reducing the percolation.

I do have a YF that I picked up and bought a kit for it but have been concentrating my efforts on the W-1 and ”˜B’. If I could get them to perform the way I think they should then I might mess with the YF.
Gotta go make breakfast for Sweetie Pie, that my big old wife you know!
Denny Graham
Sandwich, IL

First let me say that the early low cover model had problems from day one. I my self would't invest a dollar in fixing one, especially if it were giving problems. We had flooding problems, idle problems, fuel milage problems along with the hesitation problems. I have a 1956 auotmatic choke version on my '50 Power Glide and ot preforms great. May not be correct but it works for me,
The improved version "high cover" came out later in 1951 for the 235 engine. The factory would then OK them for replacement on the earlier cars that were giving owners problems. They always cured the problems and made for happy owners. The 1952 216 came with a high cover carb. and we would then install them on the early 216 cars as well.
The best place to look for the previous years problem is in the next year description of improvements. The improved carbs. are descrbed in the 1952 Features manual, 1952 Service news (late style for 235 also in about Sept 1951 serv news). The place where the best info is found is in the 1949-1953 shop manual. They list all the changes. This may be available in Keith Hardys collection. If not I can send you scans.

Ah ha, now the truth is coming to the surface, I thought for a while I was going kinda nuts. I’m SOOOOO glad to here someone of your caliber speak out on the early Rochester ”˜B’ Gene. I’ve been beating my head against the wall for the last 2 1/2 years trying to make one of those Rochester’s to perform smoothly and that’s why I gave in and tried the Carter. I’m really not all that impressed with the W-1’s performance either.
Now what just how did they take care of the problem of the base size on the later ”˜B’for the 235, they taint gonna fit the smaller bolt pattern of the 216 without slotting the holes.

I did find the 1947-51 Chevrolet Truck Shop Manual and the 1949-53 Passenger Car Shop Manual over at TOCMP and copied the whole fuel section from both. That should keep me busy studying them for the next couple of days.
I also found a copy of the 1951, ”˜52 and ”˜53 Service News, so I definitely have my work cut out for me the rest of the week.
I’ll try to catch up Gene, and once again, thanks for sticking with the subject and for coming up with an answer. One of these days I gotta get up to Milwaukee and buy ya lunch. The got any good swaps or shows up there in the summer??
Denny Graham
Sandwich, IL

Denny, Gene's '50 with powerglide whould have the 235 engine, so the 1956 carb would have the correct bolt pattern. The '52 216 Rochester could be used on earlier 216's. The bolt pattern would be the same.

Yep, I’m aware of that Cleon, I guess I was reading into Genes sentence; “The improved version "high cover" came out later in 1951 for the 235 engine. The factory would then OK them for replacement on the earlier cars that were giving owners problems,” to mean that they were replacing them on all the earlier engines.
However now that I’ve looked at the specs for both carbs I see that the standard 235 carb would have been jetted seven steps richer than the 216 and I’m afraid it would run a little rich on the smaller engine.

I'd be willing to but the farm on the fact that after nearly 60 years most all of these carbs have been rebuilt a number of times and you can bet you bottom dollar that thar was plenty of parts switching going on between any spare carb that looked the same. So to rebuild one with out checking jet size, venturi size and the power piston and spring rate you're just looking for trouble after you install it.

Denny Graham
Sandwich, IL

The high cover carburetor for a 216 would be a #7004600 (unit number). The brass tags were being phased out in 1952 so the tag probably will not be found. The bowl will have casting # 7004516 and the throttle body #7002105. Will have the correct bolt pattern for the 216 engine.
By 1952 this carburetor was sold as a replacement for 1932-1952 engines. It was calibrated to match the 1941-1952 216 engines and probably was to lean for the previous years, especially the 1937-40 that required a richer mixture.
This carburetor could be found on a 1952-53 truck with a 216 engine. That would be a 1/2 through 1 1/2 ton. (some 1 1/2 tons but very few had the optional 235 engine).
Two things can be done to install a 235 carb. on a 216 engine. Either elongate the mounting holes or use a 216 base. The carb. really isn't calibrated for a 216 and would't recommend it.
Years ago I "fixed" a 261 carb. to try on my then new 235 and it had a lot of surging problems.

The best W-1 was the 1949. The next would be the 1941-48. They made little tweeks for 1949. A slight hesitation on these (when every thing else is good) can be one of the check valves for the accelerator pump circuit.Also important that the correct 1949 inlet valve is used in a 1949 as it fits that year only. Also don't know how good todays replacements are. Years ago when a major tune-up was done wich included overhauling the carb. the techs. would just use a new gasket set, two checks and a low speed jet.
The W-1 probably floods over more easily when hot due to the cast iron bowl holding the heat longer. When I am out on the highway and its real hot I give the engine a little cool down period befor shutting it off.
From about 1948 through 1951 we used to install a Carter 414S automatic choke carb. for those who wanted an A.C. The mechanics would install them on their 1950-51 cars to get rid of the Rochester. The had slotted holes for the base so could be used on a 216 or 235. It was a Universal carb. and had an adjustable main jet. It was necessary to make the adjustment on a gas analyzer for the correct air/fuel ratio.
It was a very complicated carb. There was one on my 1950 P.G that I bought from our (woman) office manager in 1952. It ran well but I installed a new and improved Rochester hand choke unit on it. Really ran the same but the Roch seemed to have a little more "pep". Probably due to the 1/16 samller throttle plate on the Carter 414S.
When I mentioned the 414 S to Jon at the carb shop he had nothing good to say about them
I have a new one (had it for years) and tried it on both my 1934 and 1939. Didn't really run any different than the original W-1....(569 on the 34). The 414 developed an idle problem that I never fixed. Don't have any repair info for it. Probably has dirt in the low speed jet but I have no idea where it is.
I have never fooled with a YF but they look very simple. Problem is that they again are a universl carb.
The only problem I have with the present stock carbs on my cars is the fuel evaporation after sitting for a week or two. It has gotten worse year by year as the gas "improves'....and each car has an entirely different carb.
I find that its normal for a W-1 to "run better" with the choke out a hair at low speeds till its really warmed up. Seems to be the nature of the beast.
All my experiance and fooling around is done at 1000 feet above sea level. The cars have all run very differently when in Denver for an example.....and much diferent at 10,000 feet.
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