I have an 85 cj-7 and all along I thought it was having carb problems but recently bought some spark plug testers and noticed the do not flash consistantly. Plugs, wires, rotor and cap are new and plugs are gapped to
0.030". There is 275000+km on the motor. I read that the distributor shaft or bushing could be worn so I checked and I have 1/8" play up and down, 1/8" play rotationally and a tiny bit of play back and forth. The haynes manual says any noyicable play back and forth and it is time to replace. What do you guys think. If replacing, is it worth converting to the GM HEI from a salvage yard or just buy a rebuilt stock unit?
play will cause all sorts of problems including messing up the timing and spark. 1/8" play up/down is also not good. Time for a rebuilt distributor. I did mine in about half an hour including the beer break. Different setup though. You will have to mark the rotor position and the distributor position since IIRC yours has the C style holddown. Mine just has one bolt.
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Don't know about the HEI. I'm thinking about a MSD system for my ZJ.
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I had problems in my old Chevey with the HEI coil burning though the rotor and with excessive heat buildup. If I go that way again it will be an external coil.
The small play back and forth shouldn't be messing things up unless the rotor is hitting the cap...
If you are using an induction spark tester, the carb out of adjustment or with a plugged idle tube can show up on the tester as no spark or intermittent spark.
We chased one of those all over the freaking place once that showed bad spark on cylinders 1, 2 and not so bad but there cylinder 3. We swapped every part in the system before checking to see that the carb did indeed have a blocked idle tube.
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Your distributor does sound pretty worn though...
If you are going to a GM HEI, you can then get rid of that Ford emissions computer and manually set up the mix on the carb. I find having the stepper mix pins in the center of the mix travel on the BBD is the best way to start for a manual tune.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail >
Ford TFI mod is easier than GM HEI, and the only real qualified opinions I've found on the net say that TFI was marginally better than HEI. In any case it's WAY easier just a cap, rotor, base adapter (allows the larger cap to fit on the late CJ and YJ motorcraft distributor and either a TFI coil or not (it works with the stock coil or a TFI coil) I managed 39.99 for a reman motorcraft at Autozone, just the base.
That said when you did the timing chain did you check your cam for looseness in its bearings? The up/down play could be either the gear or the cam (or the gear on the cam) likely it's just your gear. definitely swap that gear out it's not hard at all just remember to mark the rotor position before AND immediately after you take it out... When you reinstall point it to the after mark to compensate for the gear rotation, you'll know for dead certain you didn't get it off a tooth... if you are comfortable finding TDC then never mind, I always feel 99 percent sure it's at TDC repeat the process a half dozen times and never really feel 100% So I like having the reference marks.
I would be doing a double check on the idle tubes. You are describing plugged ones or maybe a stuck float.
If you watch down the throat of the carb while using your hand to keep the throttle up enough to run, you shouldn't see any 'drops' of fuel coming out the venturi tubes as you give it more gas. You should only see a mist if anything.
I have found a couple sneaky dirt collectors that allows the idle tubes to get plugged up despite a good gas filter. One is the tube from the filter to the carb. When the vehicle sits, the gas evaporates in this U shaped gas line and leaves crud behind.
This crud also builds up on the float needle slider. I need to clean or replace my float needle every couple years at the tops. When it sticks, the engine won't idle, it needs half throttle to go. Again a look into the carb at idle can tell you. At least the needle and seat come out from the outside easily.
One other source of junk that plugs idle tubes, is charcoal bits. For some reason if you rn out of gas, the extra suction needed to get it going again seems to suck charcoal up from the canister which deposits it into the float chamber. Some folks with wonky gas gauges actually put a gas filter on this vent line to the canister to stop this because they run out of gas too often.
I don't know how those plug 'testers' work. I do know that an induction light will show bad/no/intermittent spark when the carb acts up. I would suspect the tester uses an LED for flashing which would likely mean it is induction based, not in series with the plug. My induction light was an expensive one and it still showed bad electrical misses with a dirty carb.
I think you are on to something, today I looked down the throat and the venturi tubes are constantly letting out drops of fuel. This is something I did not check right after the carb rebuild. One other thing I should mention after the engine warms up to operating temp. it will idle although rough. Could the electric intake manofold heater be a culprit as well. The heat stove is also long gone as is the charcoal canister and all other emmission control devices.
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