Rebuilt engine and carbs with 65 miles on it. Rays EDIS ignition.
Car became extremely hard starting and would not idle. Using my point and shoot temp gauge on the headers I noticed the front two cylinders were not heating the pipe over 200 deg while the rear 4 were off the scale. I concluded the forward two cylinders were not firing properly.
I pulled the plugs and both #5 and 6 were soaked in oil. Cleaned and reinstalled no luck.
Both cylinders have spark and I checked the firing order on the coil pack twice .
all the cylinders have compression although it’s hard to get a reading on my old leaky tester, new one on the way.
Car will start (difficult), and run. I even drove it up and down the street to move to center of the garage, and I have an uphill driveway.
The forward carb still has it’s oil in the dashpot so I don’t think it’s bleeding into the cylinders.
Are you sure it’s oil and not fuel? Since it’s the two cylinders that are ganged on the front carb, that seems more likely to be the issue than either ignition or leaking valve guides. I’d verify the float isn’t sunk, fuel bowl valve not stuck, float height fork is set correctly and that you aren’t too rich.
If you want to rule out spark though you can remove the plug and crank it over with the side of the plug grounded against the engine to verify that the spark is jumping. Do it dead cold with the choke off so it won’t be likely to start. You can use the magic button on the bottom of the solenoid to crank it.
Yes, sounds like the needle in the float bowl on that carb is stuck. Easy to check. Start the car and tap the banjo bolt on the top of the float bowl sharply with a hammer. If the engine then runs smoothly, you have your answer. Note that the problem will reappear. You’ll need to disassemble the float bowl and clean the fuel scum from the needle and seat and/or replace the needle. I use Gross Jets in lieu of rubber needles as they handle today’s lousy fuel better.
Well, when I read the “stuck float valve” solution I was certain we had it, but nope.
float bowl was full of fuel and the valve was free. Car is still not running the front two cyl.
Front carb piston travels up and down with opening the throttle. jet needle moves with the piston. All cylinders are 150 to 165 psi with plugs in.
Spraying starter fluid in the front carb revs the engine and raises the temp of the front two header tubes. Raising the piston on front carb by hand seems to have no effect but raising the piston on the others bogs the engine. So, it looks like fuel is not getting to those front cylinders. These carbs are rebuilt but I noticed what looks like a “green film” on the jet needle, almost like how brass can go green. I could wipe off a spot with my finger. Maybe the jet is clogged?
I guess I have to take this carb apart and see what might be happening.
Did you smack the nut on top of the float bowl with the engine running? This frees the float needle which sends fuel to the carburetor.
Note the float can stick the other way and send excess fuel through the overflow pipe to your garage floor! In your case, it sounds like it is stuck the other way and fuel isn’t leaving the bowl.
Based on your description, it does appear the passage from the bottom of the float bowl to the jet is plugged. After removing the float chamber top, remove the float, then the fuel from the bowl (rag or paper towels) and inspect the bottom of the float bowl.
You might want to try to blow air through that passage-will require a bit of ingenuity to get an air source down there. I would avoid using an air hose so you don’t damage or displace the jet diaphragm. A soda straw and lung power would be better. Perhaps aid the process with some thin wire (safety wire works).
If that doesn’t do it, then removal of the float bowl or the entire carb for detailed inspection is in order.
I had the same thing happen to my xj6 with hd8’s. It was also shortly after a carb rebuild. You very likely have a blockage in the fuel passage from the float bowl to the carb. Take the bell and piston out of the carb and the float out if the fuel bowl so that everything is visible. Then turn the air pressure on your compressor down to around 5-10 psi. Cover the fuel bowl with a towel so that gas does not spray everywhere and wear safety glasses. Then spray a blast of air down the carb jet to clear the line. My blockage was a silicone worm. Always have a fire extinguisher handy when working on the fuel system. Good luck.
I certainly don’t recommend beating up your carburetors.
To clarify, rap the banjo fitting on top of the float bowl with a hammer from about 4 inches above with succeeding strokes spaced five seconds apart until the needle dislodges. This takes from 1 to 3 raps in my experience. The fitting can take it.
If nothing happens, a stuck needle is likely not the problem, but it always has been for me. This exercise will get you home, at which time removing and cleaning the parts in all three bowls is a good idea. Also, replace the needles. I use Gros Jets, which have a ball bearing in lieu of a rubber needle. They are still not perfect with today’s ethanol, but they hold up longer than rubber needles, IME.
Took the float out this time and saw a bunch of “dirt” at the bottom of the bowl. I have no idea how it got there, I have 2 fuel filters and a screen between a newly lined gas tank, new fuel lines, and the re-built carbs.
Removed the fuel, removed the dome and jet needle, the needle had some kind of green build-up on it. (pic)
I used a can of carb cleaner and its straw to blow out the passage from jet to bowl, and wiped it out thoroughly. Also ran a cleaner soaked pipe cleaner down the jet got the same green stuff on the pipe cleaner.
Put the float back in checked the valve (ball valve) still works, reattached the fuel supply and ran the pump. I saw the fuel come up just to the top of the jet. It was pretty dry when I opened it.
Cleaned the green stuff off of the jet needle wit a scotch pad and reassembled.
Started right up without starter spray, and all the header tubes came up to temp evenly.
Thanks again, and any idea on what happened?
BrianM
Also note that you’re showing an open float bowl and, separately, the needle of the piston of the carburetor. This is not to be confused with the float needle, which will be either a little rubber pointy thing or a ball bearing Gros Jet that works within the forks of the float, also not shown. The failure of that needle can starve the carburetors of fuel.
That said, cleaning everything will fix your problems. Also note that changing the carburetor piston needle seat (rubber contraption surrounding the little brass hole the piston needle goes through) but keeping your original piston needle cleaned and intact will not affect the tuning of the carburetor. Just be sure to keep each carburetor and its parts as a matched set.
Sorry if I’m being too specific here. Sounds like you have it down…
The fuel vale that allows gas into the float bowl is fine. It is the ball type, not the rubber tip. The bowl always had fuel in it so that valve is fine.
This was some type of “stuff” preventing the fuel from getting out of the jet.
