The Stovebolt Site Forums The Shop Area Engine Shop Carberator accelerator pump

I have what I believe is a 1956 235 with hydrolic lifters in my 1953 Chevy 3100.

I have disassembled the carberator and replaced the acellerator pump. The origional one had a broken arm that pushed down the spring and the pump. "it looked like a kit of some kind and was not the origional arm" I got a origional piece from jim Clark classic truck parts and rebuilt the carberator.

When you run the pump with the top off gas squirts up from the spring loaded check valve next to the pump and it seems to work normaly. When you put it back together and run the pump no gas gets squirted into the carberator venturi. When you put your finger over the spring loaded check valve part and run the pump you have to be careful because you may squirt yourself in the eye. "Yes I did that... ouch"

My question is... where does the gas squirt out when it is assembled? I must have a blockage of some sort. I have the service manual but it does not have much detail. I keep looking at the top section of the carberator "the part above the spring loaded check valve" and it is solid. There is no where for the gas to go.

When you push down the gas the engine stalls and then catches up. I know my problem is because no gas is getting squirted out but I can't figure it out.

Thanks
Randall from Kansas City.

Hello Randall....Let me be the first to say welcome to the Stovebolt forum. AS you can see by my post history, I also am relatively new. This is a great place to exchange information and diagnose your problems with others. It has been a trememdous help to me.

I have your same rig in my '54 1/2 ton. I'm assuming your carb is a Rochester type B??? Although I cannot offer technical expertise on your problem, I speak from experience to say that I encountered the same type of problem last year. there are a myriad of gaskets offered with the typical rebuild kit. In may case, I had used the wrong one and the "squirt" that you refer to was actually hitting the gasket and draining down....as best I can remember, anyway. Perhaps others can chime in and offer some remedial insight to your problem. Again, Welcome!
JDJ

There are some passages still blocked. It's been a while since I took my "B" apart. I remember 2 very small hols below the plate that I used a tourch tip cleaner to clean them out.If I remember right ther is a cross tube that handles the pump gas. Carb King will chime in here to let you know what's wrong. I suggest soaking in carb cleaner for several days. then use carb cleaner with spray nozel. (EYE PROTECTION REQUIRED)

Take it apart, set it in a carb cleaner for a day or two then take it out and blow compressed air through the passages as best you can.

Jon might join in here and help straighten us out but I’ll give it a try till he corrects me.
Your pump draws fuel past the ball check into the pump well on the up stroke. On the down stroke the plunger seats the ball check and fuel is forced up the passage to the pump outlet ball check and spring unseating the ball and fuel is then passed through the smaller passage next to the discharge well and up to the crossbar where it is discharged into the venturi cluster. You may not be able to see this. The early ‘B’ carbs had a discharge nozzle that sprayed the fuel directly into the air horn out side of the cluster so it is easy to see.
If you replaced the pump without removing the outlet spring and check there may blockage at this point. If that is open then you need to clear the circuit up to the crossbar.
Denny Graham
Sandwich, IL

Denny - good post!

Jon.

Carbking,
Are there any good reasonable injection systems on the market?
dg

Dgerth _ I honestly don't know. I personally don't like fuel injection and have consistantly found that when comparing carburetors to O.E. units, the carburetor wins in all except novice cold weather starting, cold weather initial (before warmup) driveability, adaptability to a plethora of different fuels, and smog emissions.

Fuel economy, power, initial cost, and reliability (especially reliability) all go to the carburetor.

If one had an extremely radical engine, and one of the programmable EFI units, an oxygen sensor in each exhaust port, etc., etc., etc. then the EFI might be OK.

But while this old dog is not to old to learn simple new tricks, the learning curve on the above is more than I care to tackle.

We basically have fuel injection on new cars because of smog emission requirements.

Jon.

Well this weekend "Saturday" was a Rusty day. I spent the entire day working on the old truck.

I also spoke to a mechanic buddy of mine and he suggested like you that I put the carberator in cleaner and let it soak for a day! I went to the local parts store and got a gallon of the magic brew and tore the carb apart in the parking lot and droped the parts in. "I have taken it apart and put it together before so I don't even pay attention to the parts. Just take it all apart and drop them in."

My mechanic buddy "Scott" also told me not to leave it in for longer than a day because it would start to eat the pot metal that the carerator is made of. The next day "Saturday" started work on the truck. I replaced all the valve seals, adjusted and overhauld the transmission linkiage and then fixed the acellerator pedal. There has been so much rigging by shade tree mechanics on this truck it is amazing.

When I took the carberator out of the paint can it was about 2pm in the afternoon. It had been soaking and riding around in my van for a little over a day. I was amazed at how effective that cleaner was. I also noticed that it had started to eat into the potmetal because if I rubbed it my fingers woud have the grey metal rubb off on them. I read the can and it said to flush with water so I rushed to the car wash and sprayed it down. I didn't want any damage and wanted to power wash it all immiediatly. Then I dried it out and sprayed it with oil. Then I put it all back together.

One thing that is different then before is when you move the acellerator pump "after assembled" you hear this sound like something is squirting inside the carberator but no gas falls out the bottom.

I am still waiting for my pushrods and lifters to come in so I don't know if it is working properly but wanted your feed back.

I would live a detailed diagram of the acellerator pump assy so I could visualize exactly the flow. My carberator does not have the screen or the check valve. It is out of a newer engine "my 56" I am sure.

Well I got the engine back together with the new push rods and was eager to test the carberator. The carb worked perfectly! However I have a damaged rocker arm assy. My #4 exhost valve arm is very sloppy and squirts oil out the top like mad.

The good news is the carb is now fixed. The bad news is that I have to totaly overhaul this engine top to bottom. Oh well. At least I will know what I have when it is all over.