carbking
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Posts posted by carbking
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Kitty litter on blacktop, oven cleaner on concrete, a little fresh dust on gravel (just enough so you don't track the oil across the wife's carpet
).Jon.
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I have references to at least 35 manufacturers using Lycoming engines.
Jon.
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Updated through 1960.
Jon.
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Dave - if you use two primary carbs, then both operate simultaneously. Different ideas exist on whether to use choke on both or just one. Personally, I use choke on both, as the choke butterfly improves lower RPM air velocity (it acts as a straightening vane for the incoming air).
As to fuel economy:
It may (or may not) be necessary to change the jetting slightly using this configuration. However, every single multiple carb set-up that we have done this way IMPROVES fuel economy (although sometimes marginally). Of course, fuel economy certainly could suffer, depending on the "shoe size"
of the driver!The only times we will use progressive linkage on multiple carbureted engines is on numbers matching show cars with original multiple carb set-ups. This is true for V-8's with dual 4-barrels as well.
Jon.
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Gary - with the heater, you might have the "hottest" car on the track!
Jon.
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Keith - I would suggest getting your current issue corrected before doing the conversion. Don't add an additional variable into the mix.
Once you have things running as they were designed; you might wish to try two fronts. Having both carbs working all of the time improves the fuel distribution to the rear cylinders, and the engine will run more smoothly.
Pete - different carb companies used different gasket material. Stromberg did use a material that would shrink, but discontinued use about 1933 or so. The later Stromberg gaskets did not shrink. Zenith the same way. Carter used a material for their thin gaskets in the 1930's, '40's, and 50's that would shrink. This material was discontinued by Carter about 1957. Rochester used a similiar material from 1949 through the mid 1960's. This material would dry out even in the sealed repair kits, and new old stock gaskets would be shrunk.
The shrinkable gaskets would shrink from having no fuel in the carburetor (sitting long periods without being started). In the presence of fuel, no problems. I am not going to argue with the article you read, as I don't know; however, I have not personally seen issues with carburetors on vehicles that were driven, and have on those that are not.
EDIT: After posting the above, did a little research. Carter, Stromberg, and Zenith all in the 1920's and 1930's suggested soaking some of their gaskets in denatured alcohol prior to use. This would lead me to believe the ethanol would not cause gasket shrinkage.
Jon
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Your last post would seem to eliminate the electric pump as the culprit.
Ethanol based fuel has less energy than gasoline. It may be this is the cause of your surging. Raising the fuel level slightly will reduce the amount of negative pressure in the main metering circuit necessary to effect bleedover (thus causing slightly more fuel to flow through main metering).
When you are running under wide open throttle, the power jet augments the main metering jet.
Are you running the original dual two-barrel setup with front/primary and rear/secondary; or have you converted to two primary running all the time?
Jon.
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Your electric pump may (or may not) be the issue.
Consider a major difference between an electric pump and a mechanical pump:
The electric pump output is independent of the engine RPM. It delivers the same pressure and volume at all times.
The mechanical pump, driven off of the camshaft, will change volume (sometimes pressure) as the RPM of the engine changes.
For a test only, set the fuel level in the carburetor 1/16th of an inch high (again, this is for testing only). Go drive the car at your cruise speed, and see if the surging changes. If the surging is reduced, you might wish to try (A) a higher volume electric pump, (
a mechanical pump, or © increase the diameter of the main metering jets my 0.001 inch.Do not leave the fuel level high, as you could have unwanted bleedover if the car is parked on an incline.
And just for the record, the suggested pressure at the carb by Stromberg was 5 psi. Your 6 psi at the pump located at the tank should not be an issue.
Jon.
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Both the accelerator pump and the choke have been suggested as culprits. It is quite easy to test either, thus either eliminating either as a culprit, or confirming. To test the accelerator pump:
http://www.thecarburetorshop.com/Troubleshooting.htm#Acceleratorpumps
To test/adjust the automatic choke:
http://www.thecarburetorshop.com/Troubleshooting.htm#Chokes
The octane booster probably is unnecessary:
http://www.thecarburetorshop.com/Octane.htm
Jon.
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It seems some misread my intentions when I posted this thread.
Wayne - certainly agree about the patience; and we do walk our customers through trying to identify what they have. Just wanted some of the newcomers to our hobby to be aware of what information might be required, and save them (or the person calling for them) a second (or third) telephone call.
If you look on our website, you will see we have listed several articles on how to identify what one has. These have been on the net for several years. But there seems to be a large turnover in the hobby right now, with many enthusiasts just starting with their first vehicle.
And the thread wasn't meant for just us. As as example, having the trim code off of the data plate is going to help someone who is trying to order blue interior (lots of shades of blue).
Jon.
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R. W. - the purpose of the thread is to suggest newcomers to the hobby to learn about their vehicle. And there seem to be many newcomers now, which is great for the hobby.
Another issue which is even worse than the one in my first post is the individual that will look up the part number in his/her factory parts manual; and swear to me that is the number of their carburetor! They looked, and took it right off of the carb.
Our research shows that approximately 65 percent of the older vehicles are now equiped with either a service carburetor or a just plain incorrect one. In fact we often suggest the use of a service carb, as the original manufacturer found issues with the original.
Lots of vendors will attempt to help the hobbyist; but if the hobbyist gives the vendor incorrect information, how can the vendor help?
Just to point out one example (not picking on anyone!) is 1946, 1947, and 1948 Cadillac owners. I wish I had a nickle for each time I had been asked for a kit for one of these cars with a Carter number 5955 carburetor. There apparently is a mistake in the factory parts manual; as the correct number is 595S.
Jon.
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It seems this issue comes up about every 10 years or so, as there seems to be a lot of new blood in the hobby. (Which is great!). But the newcomers are not born with certain ideas which make life easier for the vendor; and cheaper for the customer.
WHEN INQUIRING ABOUT PARTS, IT IS DIFFICULT TO GIVE THE VENDOR TOO MUCH INFORMATION!!!
I get inquiries such as the following daily:
"I have a 1967 Pontiac Tempest with a 3.8 litre six and I need a carburetor kit".
What is wrong with this inquiry?
Well, first of all, I know that Pontiac sold the OHC six to try to compete in the European market, and did in fact mention the engine size in litres BUT NONE OF THE PARTS SUPPLIERS USED LITRES UNTIL THE LAST FEW YEARS. Yes, I can convert the 3.8 litre to 230 CID but why should I have to, when an informed customer could tell me he/she has a 230 cubic inch six.
OK, next. Pontiac used a different carburetor for standard transmission vehicles and automatic transmission vehicles; so what type of transmission CAME with your vehicle?
And the 230 had a 1-barrel option AND a four-barrel option; which is yours?
And remember, California, in their infinate desire to make money, started smog emission in 1966, while the federal standard began in 1968. So was your vehicle originally designed for California emissions?
Think that is all??? BUT WAIT, (as the infomercial on TV screams). In 1967, Pontiac had an early production and a late production on the 4-barrels.
So when the smoke has cleared; in 1967 Pontiac used 13 different carburetors on the 230 CID (excuse me! 3.8 litre 6) which take 12 DIFFERENT repair kits.
"Well, just go by application; they're all the same"!
Jon.
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Stefan - you are correct (unfortunately).
Our focus for the last 40 plus years has been on the manufacture of carburetor rebuilding kits, with a secondary focus on restoration of carbs (time permitting). With the resurgance of ethanol based fuels, most neopreme accelerator pumps will last anywhere from maybe 7 nanoseconds to maybe three weeks. As we make MOST of our accelerator pumps from leather (total impervious to ethanol), current demand for our rebuilding kits is the highest it has been in 40 years! We simply do not have time to restore carburetors. Not really what we wanted, but we had to based on the demands on our time.
And Glenn, thank you for the plug.
Jon.
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Fuel pumps should be available.
Try Then & Now Automotive in the Boston area. I think they have more fuel pumps than the rest of the antique world combined. Nice people too.
Be careful about that cliff. There is bound to be some government regulation against it!
And be thankful the inlet split now. If it was that fragile, it could easily have split during rush hour traffic, creating a disaster rather than a mere inconvenience.
Jon.
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Updated through 1955 calendar year.
For newer material, please call 573-392-7378 (9-4 Mon-Tues central time).
Now doing inventory control through 11 September. Will try to get back to updating the website after that.
Jon.
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The Carter AFB carbs (aluminum four-barrel) have a large bearing surface for the throttle shafts as compared to many other carburetors.
Think about it. The body of the carburetor is aluminum. Aluminum has a much greater expansion rate from heat than cast iron or steel. If the tolerances from the throttle shaft to the throttle body are too tight, then the throttle shaft will NOT rotate when the engine is at normal operating temperature.
Moving the throttle shaft with one's finger would be possible, and would probably change the idle.
I do not know about the e-clone (totally different in many respects from Carter AFB's), but the total design COLD tolerance from throttle shaft to body was 0.016~0.022 inch on the genuine Carter AFB's (so the shaft to body on each side would be 0.008~0.011 inch. Putting this number in perspective, the equivilent numbers on a Rochester 2-G (cast iron throttle body) was/is 0.004~0.006.
When we first starting bushing throttle bodies, I did a set of tripower Rochester 2-G carbs for my own GTO and set the clearance at 0.004. To my embarrassment, THE THROTTLE STUCK WHEN THE ENGINE GOT TO NORMAL TEMPERATURE!
Thereafter, we bushed carbs with 0.004~0.006 spec to 0.0055 without any issues.
As stated earlier, I do not have the specs on the e-clone. Not any desire to learn them.
Jon.
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It MAY not be the same fuel.
(1) Modern fuel goes bad in "x" weeks (you can fill in the blank), so even if it was the fuel in your tank it won't be the same after a few weeks.
(2) Even if the same station, they may have a new supplier
(3) Don't know about the plugs, not my field.
Jon.
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Dwight - most of the commercial rebuilders grouped the 261 carb with the 235 carb (because the 261 carb is quite rare!). 999 times out of a 1000 you would receive a 235 carb. I don't know of a single instance where someone bought one of these that was actually a 261 carb. The 235 carb should work other than for extreme high speed work.
Not grinding my own ax (sold completely out of 270 GMC carbs); but would suggest using what you have but watch the various sources for a 270 GMC carb.
Jon.
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The carburetor would either:
(1) require pressure on the fuel
OR
(2) require a MUCH larger fuel inlet to be installed in the carburetor.
If the carb you have is for a 216, it is too small.
If the carb you have is for a 235, it is marginal.
A two barrel carb from a 265/283 would be better.
If you wish to stay with a 1-barrel, a Zenith from a GMC 270 (same bolt pattern as the 235 Chevrolet, but larger internally) would work better.
Jon.
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34 different companies used the Stromberg U-2.
Jon.
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Stefan - acquire a copy of the Oldsmobile workshop manual, and read the section on the Carter carburetor. It is NOT a difficult carburetor, although one adjustment is easier if you were born with three hands (or have an assistant present).
There are NO special tools required above and beyond some screwdrivers, a set of drill bits, an adjustable end wrench, and a large can of patience
There are, however, a couple of special tools that were designed specifically for adjusting the carburetor that will make adjustment somewhat easier; and they can be displayed if you "show" the car. But repeating, they are NOT required. These would be speciallized measuring tools for adjustment (one is a 1/4 inch, but a 1/4 inch drill bit may be substituted), and a specialized bending tool (an adjustable end-wrench may be substituted).
You will also need a clensing agent.
When you call, will be happy to discuss.
Jon.
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Replied to your email.
Jon.
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a mechanical pump, or © increase the diameter of the main metering jets my 0.001 inch.
stromberg carb
in Buick - Pre War
Posted
In 1939, Buick used two different:
7-22 AAV-26 (standard air cleaner)
7-23 AAV-26 (heavy duty air cleaner)
Jon.