Just rebuild the carb on our 55.1 truck. All was well until the little brass plug at the end of the crossbar that has the main nozzle fell off. (See the plug with the red arrow in the picture below).
I managed to find it and pushed it back in, but now the truck won't run due to lack of gas. There are two small brass pieces that are inside the crossbar. Gently fiddling with them managed to get one loose, but the other is stuck, and in their current configuration block the air holes.
I cannot find any diagrams of these brass pieces or how the function. Does anyone else have an idea of how these things work or had any experience in fixing a problem like this?
Thanks in advance. This is a very frustrating problem.
Thanks for the link. It's the same video that I used to help rebuild my carb, but it doesn't cover removal of the internals of the center bar. If I knew how it was supposed to go together, I would dive in, but I don't want to break anything since it may be irreplaceable.
On the other hand, if I can't find out how this thing goes together, I'll have to dive in and tear the carb apart anyway, since I'll have to buy a replacement carb if I can't get this working. Hopefully someone has some experience with this.
In my experience the calibrated bleed holes in the crossbar are not to be removed during a rebuild. That is part of the air horn assembly and are not serviced separately. If you've disturbed that you may need to get another carburetor. But, don't take my word as gospel, I'm sure an expert will be along with a better answer, at which time I'll bail out of the discussion and let them take the reins. dg
I was afraid of that. I certainly didn't mean to remove the plug or move anything in the crossbar, but it fell out and I did my best to put it back the way it was.
I did find the original patent, in the case anyone needs a good diagram:
It appears that the tube is simply in place, but that the small needle like flat pin that sticks in the inlet side is not described in the patents or the bulletin. I'm hoping that resetting it will fix the problem. I'll keep you all posted with an update. I'd hate to get another carb or switch to TBI.
Talk to Mike at Mike's Carbs. He's the one who made the video. He also has a web site that you can download your carb service manual for free. He would know exactly what to do. Good luck!
Thanks wrenchbender! I don't think these parts are meant to come out, at least not with some serious work involved.
As for Mike, I did e-mail him. He said the brass plug has to be in, but otherwise it sounded like he did not know.
Moved the pin back to original position; truck still getting no gas. Going to play with the float levels. Maybe that's the problem and not the pins etc. whatsoever. Will post with an update.
Just opened up the carb again. We now have gas in the float bowl (as opposed to none before resetting that pin in the crossbar) but we must not be getting enough. Time to play with the float levels.
It appears as though the mystery of the crossbar is solved, although I'm not going to believe that 100% until I get the truck running. Stay tuned.
Once the float is sitting flat with the top upside down so we can see where it is resting, there should be 1-9/32" from the very top of the float pontoon to the gasket. They supply a measuring square with the Carb Kit. These are important measurements, so be sure you understand what you are reading. To change that measurement, very delicately bend that center tab in or out so when it sits on the needle valve, you get the proper measurement. Next, turn the assembly upside down and let the floats dangle. Now measure from the gasket to the top of the float pontoon and you should have exactly 1-3/4". If not, there is another tab that is bent for that in the center of the assembly.
The float at 1 9/32" dumps gas everywhere. The original float and the one that came in the rebuild kit came set at 1 23/32". That setting doesn't allow enough gas in, where as the 1 9/32" setting dumps gas like a hose everywhere. Kind of weird. I'm going to play around with the settings tonight and see where it likes to be. Hopefully that's the problem, but no guarantees. Will update.
Any progress Grover? I am curious because I have a Roch B on my 261 that just overflows and dumps gas everywhere. So dangerous and it was after a correct rebuild. It doesn't do it all the time though. Something is getting stuck every now and then. The last thing I tried seemed to fix it. The floats were getting caught on the gasket sides. I haven't run it enough since then to be 100% sure it's fixed. These days I clean, test and clean and retest after a rebuild to make sure things are right. Didn't used to have to do that back in the day. Dunno.
Sadly, haven't had a chance to retry it yet. I've been working 12 hour days, and just pulled the front axle off and am in the middle of trying to get a disc brake setup on the front wheels, so I've been working as much as I can before I collapse at the end of the day. I'll try and get to the carb as soon as I can and report back here. Found out I may have to move at the end of the month, so my priority changed to getting the truck rolling so we can push it out of the driveway and onto a trailer if need be. Life can be crazy sometimes.
I'll let you know how the carb goes. On the upshot, I don't think the float is sticking. We've tried two different floats, and there is no sign of wear on either where it would contact the side of the carb.
On vehicles which are infrequently started; the float sticks because of the residue from evaporated fuel which acts like a glue. GENERALLY (not always), fresh fuel will dissolve the "glue" and the float only sticks for a few minutes.
This will occur on a used, rebuilt, or new carburetor.
The solution is easy. Start the engine sufficiently often to not allow the fuel to evaporate out of the carburetor bowl.
Jon.
Good carburetion is fuelish hot air The most expensive carburetor is the wrong one you attempt to modify. If you truly believe "one size fits all," try walking a mile in your spouse's shoes! The Carburetor Shop
Finally got the problem solved! I think we had multiple problems.
At first, the small brass inserts in the crossbar of the air horn were blocking the fuel spray. Fixed that.
Then we had an issue with our needle and seat.
The rebuild video from Mike's carbs advocates spraying some air in while you gently hold down the needle to make sure it seat well and doesn't allow air flow. Our original seat sealed better, so we went with that, and left the new one in the bag.
One of the classic car guys in our town came by today and looked at the carb. He showed us that the tab on the float wasn't pushing the needle into the seat in a uniform manner. It should push the needle directly up, or as nearly so as possible, and ours was pushing the needle up at an angle.
So, after rebending the tab on the float to make it push the needle in a straighter fashion, getting the float adjusted properly (1 9/32" with 1 3/4" drop), and then replacing the seat with the one from the rebuild kit (despite it not seeming to seal as well), everything runs now.
It may still be a bit rich, but we're not dumping fuel everywhere now, and the truck runs smoothly (much better than before the rebuild) and we're in business.
