Post by alaskanrocket on Apr 20, 2020 14:14:01 GMT -5
Heres where I'll start. I did a rebuild on a L134 this winter it's .060 over and still within tolerances so I put new pistons, rings, bearings throughout, and new valve guides reamed to spec and lapped the valves the best I could. A back story, Ive been fighting this jeep power train for years, this is the third engine Ive put in it since I never want to spend the money to get one properly machined and rebuilt. Good blocks are hard to come by in Alaska, they have either mismatched bearing caps, bored out to .060 and clapped out, or cracked, etc, etc.
Ive only driven it once since the rebuild and it didn't go well, it ran fine for the first 5 minutes or so then just died, seemed electrical at the time, checked all the connections, jumped back in it and still wouldn't fire, gave it some choke and she fired up and would only run partially choked, barely made it home. Since then replaced the fuel tank with a new one and new fuel lines suspecting there was some junk in the tank. Ive been working on getting it adjusted properly since then and this is where im having my current issue.
The data I have.... Rebuilt carburetor with parts kit from one of the reputable jeep parts dealers after I completed the engine rebuild, Installed new base gasket with diffuser and torqued it down (did not use torque wrench but pretty good oomph on it all hundred times ive had it off and on) New points set to .020, new cap, rotor, condenser. The distributor bushing does have a bit of play, (its insane that I have 5 distributors and they all some issue or another). Static timed the engine and it fired right up with no issues (this was right after the rebuild and before the initial test drive). Oil pressure was around 40psi at idle when cold, then drops to around 10psi when hot. Timed by Vacuum from the intake manifold and vacuum was relatively steady at 20PSI. (Since then with all the fiddling with everything vacuum is now around 19psi). Checked compressions warm and dry and had 100,95,100,100 (with the intake closed)
Adjusting the carb.
Initially on fire up I adjust the idle speed screw to open enough to run and the mixture screw to 1.5 turns open, it only idles smoothly at fairly high idle rpm. The engine has a miss at idle and seems to smoke a lot, I'd like to attribute this to a rich carb condition but Im not ruling out oil since I didn't do any real machine work to the engine and a lot of stuff was close to max tolerance. Pulled the plugs and after the 5 hours or so of troubleshooting run time they were pretty sooty (not oily), so cleaned and re-installed (autolite 295's). My dwell/tach meter isn't working so Ive not been able to check rpm/dwell yet. Checked for vacuum leaks all around the carb with propane and didn't find any. Ive attempted to run the idle speed screw down to where it barely runs and adjust the mixture screw but it never really smooths out. Once I increase the idle speed screw to where the miss goes away the idle mixture screw does nothing, I can screw it in all the way and it makes no change to idle speed and the carb is still very responsive, I should note that there is not fuel coming through the venturi at this point or anywhere else above the throttle plate as far as I can tell, the potential is there and I just cant see it but I don't think so. Ive tried to lower the idle down and apply choke and it immediately wants to die. Ive checked the plunger travel and it is at scout pilots recommended heights and adjusted the metering valve with the proper carter tool, I have also made sure the float setting is correct with the proper carter tool. Ive spent quite a few hours working on this, researching, and then messed with it all weekend and cant get rid of that miss and seemingly rich condition. Ive read tons of stuff in the forums and on this site and even discovered my distributor advance was seized up (now fixed, thanks to this website). Im not really sure what else to do from here. The carb is currently torn apart on the bench looking for a plugged jet or something else glaring and Im starting to think this may not be just a carb issue. I feel like I need to go back to square one and start all over in case ive missed something.
I'd appreciate any input on where to go from here. Thanks in advance and I'll be happy to answer any further questions, hopefully I answered most of them above. Thanks!!