MB309basket said:
Is a float adjustment something that the internet can teach me how to do in part of an afternoon; or does one typically remove the carb and send it in for a complete rebuild?
Thanks.
Since we all seem to have overlooked this question, let me give it a try.
Adjusting float level requires removal and disassembly of the carburetor, or, if you are confident about taking carbs apart and not dropping tiny screws down the throttle bore, you should be able to make the adjustment with the carb still mounted by removing the top of the carb from the base while it is still installed. This exposes the float bowl from the top and allows the float to be removed.
Adjusting the float requires VERY SMALL changes in the bend angle of the drop limiter tab. You want the float to seat the float needle while it is closer to the bottom of the bowl rather than toward the top. Too much adjustment in this area will leave you starving for gas under acceleration or other fuel starvation issues due to too little fuel in the bowl. Float arm should be about dead level to the horizon when correctly adjusted, so just a couple of degrees below horizontal should be sufficient to drop the bowl level enough for you to see an improvement in the ability to do off-angle trails. While you have the carb apart this far, verify that the float needle is perfect. If it is not, replace it now. If you are lucky, you can do all this without having to replace gaskets. If you tear up the bowl gasket, get a new one. It will work with a torn gasket, but will probably leak gas which can be bad on the trail.
The real problem you face, however, is that the stock carbs are not designed to suffer steep angles. They intentionally overflow fuel from the bowl to the intake when tilted more than about 20 degrees. You could experiment with raising the overflow inlet height, but such modifications require a degree of design and fabrication skill that is beyond written discussion. If it were easy to do, lots of folks would have done it over the last 35 years of living with Jeep carburetors. That they are not easy to remedy is the reason there are so many aftermarket carburetors still available today. One replacement "off road" carburetor even has a raised vent tube which puts the vent so high that it would literally have to be upside down to leak. If you can find a way to modify your carb to put the overflow vent higher by even a quarter inch, you will increase the roll angle you can sustain by a significant margin.
Add to the situation with the older carbs the probability that if your carburetor is the original, the throttle plate rod is almost certainly worn out and leaking, which causes air leaks that drive the idle speed around uncontrollably (rough idle). Most older Jeeps have trouble controlling idle speed, and often the problem is attributable to this issue, caused by time, dirt, and wear. Another issue that can not readily be repaired. The throttle body needs to be bushed and the rod replaced, or a rebuilt carb needs to be installed to fix a leaking throttle plate rod.
If you have the time and money, fuel injection is the best option. Otherwise, I would look for a replacement style carburetor if you intend to take the older Jeeps off road regularly. The stock carb will simply drive you crazy on the trail. Most of the Jeep catalogs have replacement carbs available and the prices are fairly consistent from source to source. If you do this, don't go crazy with larger models or expect performance increases. Marketing blurbs all refer to increases power and better economy. Reality is that they do function better off road, but deliver economy no better than stock, and usually worse than stock unless you are very good at rejetting carburetors. For general off road work, a smaller bore carburetor will give you better economy, better torque, better throttle response, and will be easier to adjust to your engine. since we usually don't drive WOT on the trail, big bore carbs don't do any good off road.
