The Stovebolt Site Forums The Shop Area Engine Shop need help picking a new carb

hi there, I need some help picking out a new carb. Its about the only thing left to change. Nothing else i have tried seems to be correcting the problem. Changed fuel pump, lines, vented the fuel system, and still does the exact same thing. Runs about half an hour, and then the carb is out of gas, there is fuel in fuel pump, using glass bowl type fuel pump. Running a 55 235 engine in my 1946 truck. trying to find out what would be the best carb to put in it. Rochester or Carter. Beginning to think the carb itself is not venting, so I am going to replace it. Is there one carb that would be better, or is it just a personal choice. Running a one barrel carb right now from Napa. Any suggestions would be greatful.

Once it runs out of fuel, how do you restart it? How long does it set?

I would bet that a new carb will do the same thing. The float is the controlling factor in the fuel delivery. If it sticks, they flood out or go dry, and either one will happen pretty quick if you are driving. I can't see it happening over time and fixing itself.

Are you sure its not icing up? 30 minutes would be about right to form a good layer of ice down in the venturi.

If you go with a replacement carb, stick with what the factory used.

Joe

Hy shmkr, it sounds like some dirt/rust in the tank is plugging the fuel line. Have you cleaned out the fuel tank? Have you tried gravity feeding the carb, to see if it runs past a half an hour. Have you checked to see what the fuel pressure is at the carb when it quits, to verify it has or has not got fuel pressure?

well it's not the fuel tank, we sent it in and had it cleaned out and relined. I know its not a venting problem because we drove it on the weekend with the gas cap off and it still did it. Let it sit for awhile, then got a boost, and it fired right back up. don't think it is icing up because it did the same thing last summer. Rerouted the fuel line becuase we thought the fuel might be boiling in the fuel line or carb. When it did it on the weekend, i checked and the fuel pump was full of gas, it is brand new too. Talking about scratching your head, AhHHHHHHH.Talked to one mechanic, and made a suggestion about putting a heat sheild under the carb, not sure about that one. Engine is not heating up running a 180 thermostat, and guage is showing its not heating up. Getting really frustrating.

tore the carb apart so many times to see if i could find something sticking, the float and cant find anything that appears to be sticking. this set up worked fine for over two years with no problems and now the last year, crap. took it into a garage to see if they could figure out, and they made it worse. the carb was [censored] gas all over the place, and i had to fix it. some help. somebody else told me that all three things, the fuel pump, carb and tank all have to be vented, have no clue where the carb is suppose to venting from and even if it has a place to vent. Its already an aftermarket carb from napa.

Can you dribble a little gas down the carb throat when it stalls and make it run for a short time? It's possible you've got an ignition-related problem, not fuel. The first thing to do is to be absolutely sure you've got a fuel supply problem.

Jerry

yes, tried that,no gas in the carb.had earlier problems with the main ignition wire getting hot, but have resolved that, wire no longer gets hot. Just before it stalls out, it starts sputtering and carrying on like no gas in tank.. start pumping the pedal, and it tries to keep going, but eventually quits. any more suggestions, cause im running out of ideas!

You had the fuel tank boiled and relined. Check

Have you checked the pump by removing the line from the carburetor and pumping fuel into a can?

Are there any rubber lines on the system that could be contracting under the pressure of the fuel pump? You said you rerouted the line but did you reroute it from the fuel tank to the pump? Then from the pump to the carburetor? I have had problems with the connecting rubber line under the cab.

Just a few thoughts before blaming the carburetor. Or tearing it apart.

I hope this helps

yep checked the pump, its pumping at the pump, you can even see it pumping in the glass bowl on the pump. Rerouted the line from the pump to the carb. It was going straight up and around valve cover. Now got it going down and under the water pump and then up to the carb to see if that made a difference, nope. the one coming from the tank follows the frame and then over to the fuel pump.
earlier when i had ignition problems, the engine would just quit period, no sputtering or caring on. the steel coverd ignition wire was hot. got that problem fixed.
when she quit on the weekend the pump was all the way full.

Do you have the insulator between you carburetor and the intake manifold?

we tried earlier to find a rebuild kit for the carb that was originally in the truck, no numbers or tag on carb, took it into a carb shop, couldnt come up with the right rebuild kit for it, tried all he had, all different, so went to napa and got a different one, trying to figure out, what would be a direct replacement, and the right carb for the 235 engine. Napa now is being no help, the need a number

I have a rochester single barrel on my 55 235. It runs well.

Just make sure the insulator is set right. There is a hole in the manifold the needs to be connected to the carburetor.

Best of luck.

If it has gas pumping to the carb,I bet the float is stuck.I would check the needle and seat at the float.Jim carter has carbs and carb kits.
carbs and kits

float adjustment

I had a similar problem, turned out the tubing from the 'new' tank was FULL of crud, new line fixed it. I also have gotten an inline pressure gauge so I can see what is really going on.
I also quit using the fuel pressure regulators that I used to rely on, the new ones are junk, can stop the fuel flow at the worst possible time.
If all else fails go through the tune up proceedure per the shop manual, just may stumble onto the problem.

what kind of pressure guage did you get and where did you put it in the line? just curious.

not sure what you mean about insulator between carb and intake, could you please explain that

This is the insulator that Dennis refers to, above. It goes between the carburetor and the intake manifold, with the slot side up (as shown in photo). The slot in the insulator has to directly under a hole in the base of the carburetor.

The Shop Manuals make no reference to carburetor gaskets, but most people at least put one between the carburetor and the insulator (note the slots in that gasket are such that you do not have to worry about orientating it properly.

Old vacuum gauges usually have a pressure side to them for checking fuel pumps. Just "T" it in line right at the carb inlet and run the hose out so you can see the gauge while driving. Hold it down with the windshield wiper, don't run it in the cab! Any good pump should hold 2 1/2 to 5 psi and up to 6 or 7 at idle. Glass bowl filters are kind of deceiving, they can have fuel in them but its not going anywhere.

Joe

oh ok no there is not really an insulator but the gasket that came with carb. can i ask what the point is to the thick insulator?