Need a bit of help adjusting the float on my Rochester B carb. I’m doing a rebuild and it says that the float level should be 1 9/32” and the float drop should be 1 3/4”. The float drop measures perfectly at 1 3/4”, but the float level measures 1 14/32”. I’m 5/32” too high and the adjustment pad is practically flat with no more room to adjust unless I push it past level. Should I do that to get it to 1 9/32”?
The position of the tab looks pretty normal to me. A very small change makes quite a difference out on the arms where the floats are located.
If it hasn't been straightened I will go with a taller setting (like 1 3/8 or so) so that the fuel level in the bowl will stay lower. This (a) makes it run a bit leaner and (b) keeps fuel from sloshing up where it will seep/weep/leak at that gasket line. You're at 1 7/16 and this is a little too tall. Fuel will cutoff a bit too soon. Just push the tab down a bit and check. This all got out of whack when the needle and seat changed. The old needle/seat let the float sit closer to the air horn when fuel cutoff occurred (meaning your fuel level would have been higher in there). Good luck.
Got the carb all back together and installed on the motor. Truck started on the first try, but then ran at full throttle! Stomped on the accelerator and nothing happened. Pulled the throttle and nothing changed. I shut it down and checked everything....... accelerator return spring still attached and working well. The throttle cable was correctly installed and not bound. Choke cable installed correctly and working properly. Accelerator pump working up and down nicely and not stuck or bound. Tried it again and the same thing happened. What is causing it to run wide open like this?
Need to pull the air cleaner, look down the throat and see where the butterfly is. Should be closed, sounds like it's not...by a lot. Time to adjust the throttle/accelerator cables.
Although you did state both cables are adjusted properly, can't imagine it going to wot without the throttle plate being out of position.
Check the pivot on the linkage bell crank didn't flip over to the other side
Thanks Ron and sstock. I’ll look down the throat and note the position of the butterfly. I’m sure that it’s wide open. Sstock, what is the linkage bell crank? Is it the long arm on the side with the coiled spring on it? That was a bit confusing when I put it back together.
Bell crank is the pivot assembly that bolts to the block, its function is to change direction 90 degrees from the foot pedal rod to the throttle arm.
Okay, that part is working fine. No problem with wear or restriction.
My point is with the return spring on and the linkage unhooked from the carb, the bell carank can pivot past its fulcrum and make it so when you hook the linkage back up it is at full throttle.
I can send you a picture so you can double check that your linkage is just like mine.
Chris, please send me a pic of the linkage side of your carb. Thanks!
Okay guys, I need some help. I just finished taking the carb back off the motor in hopes of finding that the bottom butterfly was wide open or was at least binding, but I found no such thing. The butterfly was closed and moved easily whenever I moved the accelerator lever. (or whatever it’s real name is) I was hoping that I would find it stuck wide-open and that would be the cause of it running wide open when I first started the motor last Sunday. I’m really puzzled now about what the cause of it is. If anyone has any ideas I’d sure like to hear them. Thank you.
Moderator, tell me if I need to start a new post since this is a new problem and I’ll do so. Thanks
Did you verify that the throttle valve was closed prior to removing the carburetor?
How did it run before you worked on the carburetor?
A massive vacuum leak can cause a high idle, but not full throttle.
The Rochester B has what is called a "snatch idle" circuit. Fuel is pulled in through the main jet, up and across the main output orifice...the bar you see when you look down the throat and then to the the idle bleeds. If you hark back to the stuff I posted over a year ago on the Rochester B, maybe you can see how this works. Obviously something is very oddly wrong here. If your bottom butterfly is closed, I can't imagine how you could be running at full throttle. You simply can't get enough air so even if you're pushing too much fuel through the thing, the mixture would be way too rich for it to even work. Sorry I don't have the answer. I'm stumped at the moment.
Just to confirm- - - - -have you looked down the carburetor throat with the carb installed, and verified that the throttle plate is closed? Doing it with the carb on the bench is no guarantee that you're not making a mistake hooking up the linkage. Also, since the fast idle cam and the position of the choke interacts with the idle screw, what's the possibility that the choke linkage has been assembled incorrectly? An "idle" speed in the neighborhood of 2,000-2,500 RPM is going to sound like WOT, even when the throttle blade is only slightly open due to a sticky fast idle setup.
52carl...... it was running near perfect before gasoline started pouring out the bottom of it and the engine wouldn’t crank. That’s the reason I had to put a kit in it.
Jon G........ yes, I looked down the throat of the carb and the throttle plate was in the closed position. Moves freely when the lever is pushed up and down.
Jerry ....... I have attached a picture this time showing you how it looks after assembly. Did I do it incorrectly? I backed off the idle setscrew so it’s not even functional at the moment.
The only vacuum leak issue I discovered was a split in the hose coming from the manifold to the wipers. But it’s not very big. Distributor vacuum advance hose was attached.
If it looks like I have assembled it correctly and we’re all still stumped as to what the problem could be, I’ll reinstall the carb and try starting it again.
Thank you Moparguy, I don’t believe I have reassembled everything correctly according to your pictures. I just put the carb back on and started the engine and the same thing happened. I quickly pulled out the screwdriver and took off the keeper on the throttle cable allowing any tension to be relieved. The engine started to slow down, so I manually pulled down on the accelerator rod and it came to a normal idle. I concluded that I must have tightened the throttle cable too tight in the linkage, although the throttle knob was all the way in. I let it idle for 20 minutes and it ran just fine except for gasoline weeping from the fuel line-to-carb connection. I’ve tightened-loosened-tightened it 3 times and have it 98% stopped. I’ll eventually get it completely stopped. I think I have solved my problem, but keep your fingers crossed!
Just got back from a test run and it wasn’t so good. Lots of hesitation when I accelerate, and it backfired several times. Got back to the house, popped the hood, and noticed gasoline dripping pretty good from the back of the carb. Frustration has definitely set in. All I did was take it apart and put a new kit in it. I didn’t change any of the settings or turn any of the adjustment screws. You would think that it would run pretty well now!?!
Rochester's are notorious leakers. Check to see exactly where the fuel is leaking and report, help is just a few key strokes away.
How much cleaning did you do while the carb was dismantled? Unless EVERY passage in the carb gets a good soaking in an aggressive solvent, a hot water rinse, and massive amount of high pressure air blown through it, you've probably only succeeded in creating problems that weren't there before. Back when I was working for a living, I paid a lot of bills and fed my kids a lot of good food, with money I made while correcting carburetor problems caused by guys who "just put a kit in it!"
Ok Jerry, why don’t you just tell them that you had to school me and correct my ignorance while at homecoming a few years back! Oh wait, you weren’t bringing it up.... cats out of the bag now!
I have a “rebuilt” Rochester sitting in my garage in a box. I never tested it or tried it. It’s yours if you want it. It is extremely clean but I’m guessing we should go through it because I don’t trust people unless I personally know that their word is good or they have a good reputation in the community.
Thanks Chris! I’ll call you this weekend about the carb.
Reminder, it’s been sitting so it might need work. I’m not sure!
I can't help but wonder about a vacuum leak causing the fast idle. Especially after seeing the cracked vacuum hose coming off of the manifold.
I was thinking along those lines also. When he swings to get the carb I have sitting here I can give him a cap to plug off all vacuum lines. Unless I am wrong, it should be an easy check.
Chuck, I have friday off if you want to do some work on the truck.