VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 Rochester 1 bbl leakage

I had my Rochester BC 1 bbl carburetor on my 1939 car completely overhauled with new parts from an overhaul kit, and all other parts are cleanded and checked. It was working fine, the engine was running better than ever. But after about 15 miles drive, the car suddenly stopped, and I saw the carb was overfloaming and leaking a lot from the opening where the vertikal throttle arm goes in.
What can be the reason for the overfloaming?

It was caused by a piece of dirt or ? being stuck under the needle valve. Not the fault of the carburetor. This prevented the valve from shutting off the gas supply and the bowl overfilled.

defective float ? ( pin hole in it ? )

As Gene and The39 responded. For some reason the needle valve is not shuting off flow of gasoline into the fuel bowl. As they pointed out, I would chase that problem first.
Charlie

You may want to take the gas tank out and look inside it. Don

I see that dirt or foreign elements can be a reason.
Some more information: In october I added some "fuel clean" additive to the gas tank. After that I was just driving a short distance before my carburator failed. Then I was dismounting it for an overhaul, and the car parked for the winter season. The guy who made the overhaul said it was an necessary overhaul, since it was in bad condition. After that the fuel additive has been in the fuel tank for several months.
On my first drive this year with the newly overhauled carb, the engine was running great until a it came to sudden stop.
Maybe the "fuel clean" additive has forced the problems, by leaving some more dirt from other parts of the fuel system, which has ran into the carburetor to block the valve?

I doubt that the fuel additive alone caused a problem, it may have loosened some crud in the fuel tank or lines. If the carb is a Rochester B or BC disconnect the fuel line, and stick the end into a 1 or 2 liter clean soda bottle, use a piece of hose if needed to keep the bottle upright, REMOVE the high tension coil wire and use the starter to crank the engine until you have at least 3/4 full bottle, and examine the fuel n the bottle. If the fuel isn't the same color and clearness as when it went into the tank, consider cleaning or replacing the tank, the additive laden fuel may also have unlodged some debris from a restriction or fitting in a line or from the tank, or fuel pump. Also remove the top of the carb 4 machine screws and a couple of linkage rods and cables and examine what is in the inlet (needle and seat) and in the float bowl. The float should be empty and light. I want my car to run better than I want it to look, so I cut the line 4" from the carb and insert a expendable metal cased fuel filter, I also replace it when I do an oil change every other time. I use some Seafoam and some Marvel Mystery oil with every tankful of gasoline, just for my peace of mind, since then I have never had a stuck valve or a bad experiance with the fuel system, I have changed out a couple of fuel pumps before they failed to operate, that wore out and started leaking. Parts on these old cars hardly last 125,000 miles or 10 years.

Your shop manual and owners manual is a good source for doing regular maintenance on schedule.

I bet you have a inline filter as well as a fuelpump filter and maybe a filter before the fuel pump. I doubt dirt would get by all three, and besides you can see the dirt in the float bowl and other filters. I have a Rochester that I took off my 38 and replaced in with a Carter (which I love). The Rochester started out running fine but a few miles down the road it would starve for fuel. Everyone said it had dirt in it,but I wanted the Carter anyway so I bought it. If you would like it(free of charge) I'll mail it to you. Maybe you can use the parts or get to run,or whatever. How's that for a good ole boy from Tennessee?

My car has a 235 (56 chevy) long block with everything else being a 216 orginal 38 chevy,including the intake. If you have already swapped for a 235 complete engine this Rochester will not fit.

Email me if you're interested. wawuzit@comcast.net

Would you expand on your install of the 56 235 long block? Water pump, pulley, harmonic balancer, flywheel, and modifications to the intake exhaust? I have a 235 out of a 54 automatic car I am putting in my 40 sedan. thanks, dave

The 235 was already installed when I bought the car. The head/block (long block) numbers are 235 /1956 car. I know the exhaust,intake,carb.,etc. are 216 for sure.

Below is a good link for you.

http://www.1941chevrolet.com/ChevyEngineSwap.html

Send that Rochester by mail to me and I will clean it and put in a new kit and keep it ready for someone to use at my cost. Do you have a picture that you can email? That's not necessary but I can get an idea about the age of the carb from a good picture of the outside looking toward the throttle linkage side.

I sometimes buy parts carbs on eBay when the price is right, and I keep a supply of jets and parts for my own use, I don't sell any parts.

I will reimburse you for the shipping charges. Most modern Carter W1, Rochester 2 BBL and Q-Jet mechanics don't really know how to clean and repair the Rochester model B carbs, thus they promote the "old timey" technology and inferior Carter W1. I have made my 30 year study of the model B and a lot of what I have learned is from a book, but not everything is from a book.

Mrmack's svs.
155 ocho rios rd.
comanche TX 76442

P.S. I think that, you can easily overdo the filter game, Two good inline filters, one before the fuel pump and one before the carb are adequate except for the worst sceniero of a badly crudded, rusty tank and fuel lines. I do like to use a settleing bowl with a WIX or A-C filter element for simple ocassional water-in-gas and normal crap in the system, leave the bowl turned down and observe the stuff in the bottom of the bowl. I have found that amateur cleaning and sealing the fuel tank with snot is kind of like putting a bandaid on a severed leg, and cause more problems when the lining comes loose in pieces and plugs the system. Use a pro or buy new repo .There are vendors selling replacement fuel tanks and fuel lines. I make up the long fuel line from the tank to the fuel pump by buying already flared and fittings easily formed to shape steel line from your local auto supply store and make the fuel lines, iit depends on legnth as to how many brass coupleings you will need. I do buy already formed fuel lines for pump to carb. NCA has them for 50-54 cars either for a settleing bowl at the carb or no filter lengths. Other vendors probably also have them. (of course all this is my opinion).

Mack,
I partially agree with your post. Yes some of us that have years experience with the Carter W-1 carburetors are not big fans of putting Rochester B carbs on earlier vehicles. It is not a matter of one being necessarily better but the carburetors were matched in cfm, mixture, etc. to the specific engines used in various years.

A second reason is that I still have problems totally understanding that darnfurnal power valve. I'm learning but still have a way to go to accurately troubleshoot those beasties. That is why I send the Rochester guys to you instead of messing up anyone elses carb. I can mess up mine and it only hurts me. But if I mess up someone elses I risk infuriating several other people and I don't need any more of people PO'd at me.

Me neither, that is one of my talents, infurations I think it is caused by Adam eating that apple, and me eating that durned wedding cake back in 1965.
But let's not expound too much on this, know what I mean?

Chipper, I don't advocate using a Rochester model B on the cars and trucks before they originally came out from the factory, I just don't advocate regressing to a W1 on 1951 up models. The power valve circuit is hardly easy to get into the mind, I had to work both ways from the throttle body base vacuum supply up and then down as fuel air flow moves several times before I got it, trial and error took a while.

I still have to consult my notes if it has been a while since I worked on one.

I still haven't received the one from the elder gentleman that called. Maybe he got it fixed, or had another problem.

Here's a few photos.






I'll send it to you,if you can help out our buddy from Norway or someone else,please do.

Sounds like a good deal to me, ship it out. I value what our neighbors and VCCA members over across the pond are getting done on their old Chevrolets, and think that we should offer help anyway and anytime we are able. Many of them are good VCCA members. I am glad that the VCCA.org site can help them with joining and renewing their memberships, they pay their way.

By looking at the lid I would say that is the first design of the Rochester B. The next one which I believe arrived in 1952 had a thicker edge to it and some improvements inside.

Bth the early low coaver and late high cover Rochester carburetors can leak at the front of the bowl. They seem to warp out of shape. I took a late cover and reformed the cover but after a few months it leked again. A gas resistant sealer could be applied to both sides of the front portion of the gasket.

It'a headed your way.

I'll be waiting and watching...

The guy who overhauled the carburator, say it is a broken valve gasket. Now we are waiting for the arrival of a new overhaul kit, had to order a new one from Filling.
I find it strange that a new gasket is broken. How is the quality of the overhaul kits on the market?
Is it any possibilities that any external component have caused the error, e.g:
Fuel pump pressure to high?
Vacuum line malfunction?
Other reasons?

Wouldn't something like permatex or form-a-gasket do the job? I guess the correct way would be getting a new gasket,just thinking out loud.