Missing badly.. or starving for fuel..

[timdogge]

Hello all! Fist time post and new 78 owner. Bought this car a month ago from an older gentleman who owned it since New and kept very good care of it until 6 years ago. It sat for six years in his garage. I got it home and immediately changed the gas tank, sending unit and flushed the lines. Turned the key and she started. Ran very ruff with a loud rattling coming from under the timing belt cover. I took the cover off and found the timing belt tensioner was shot and clearly out of time. When the tensioner gave I guess she jumped time. I bought the timing belt kit with water pump. Could not for the life of me loosen the crank nut so I installed the new tensioner and timed her and left old belt on. Turned the key and she purred like a kitten.. took her out for a 30 minute spin and two minutes before getting back to the house she started bucking. Coil is original so I went and bought a new coil and swapped it out. Burned a point in the process so I bought pertronix electronic ignition, new wires, cap, rotor, spark plus. Put all that together and and still running horrible. She revs up fine, but won't idle and misses bad at lower rpm. Any ideas?

[RRoller123]

You have to get that nut off and change that timing belt immediately and time the cams accurately. The risk is enormous. The 2L engine is not an interference engine (unless the large valves are installed), but the other engines are, and if the belt breaks, the valves will hit the top of the pistons. If the belt jumped, as you suspect, it is a big problem.

I used a chain wrench on a breaker bar with a pipe extension to hold the pulley, and a breaker bar and pipe extension on the wrench to get the nut off, takes 2 people but it works like a charm.

I took the radiator out, but a sheet of 1/4 ply or heavy cardboard in front of it will probably protect it from the wrench, but the risk of damage to the fins is quite high unless one is very careful. It is really tight in there in front of the pulley. I biffed a lot of fins before I decided to pull the radiator.

(If the inner sheet metal shield is still installed, most people toss it, as it is a royal pita.)

[tima01864]

One thing to note: Fourth from the top In the above diagram, Shows a metal timing belt cover, If that has already been removed from a previous belt change removing the crankshaft pulley is not necessary

[SteinOnkel]

First things first. Check the marks. Crankshaft mark the first of the three lines on the timing cover (when counted in clockwise rotation viewed from the front of the engine) is TDC. Then look into the back of the cover on the top. Each camshaft has a dot and a pointer on it. It's sometimes easier to see and makes more sense with the cover removed. Not a great design.

Next up I would do a compression test, then go from there.

[Jeeptechfred]

I don’t suspect that your problem is cam timing. Otherwise it would run poorly at higher RPMs too. The most likely cause is would be a vacuum leak iif it misfires only at lower RPM idle. Could also be fuel mixture issue in idle circuit of carb.
Does it feel like one cylinder or multiple cylinders? If one cylinder isolate it but one by one pulling off ignition wires. Beware easy to get zapped. If you can trace to one cylinder then look in that area for the leaks.
To remove the cramk nut what we used to do in a pinch with other cars (haven’t tried it on a Fiat) is to put a breaker bar on the bolt head, wedge the bar against the frame and bump the starter. The starter motor will then usually crack the bolt loose with ease.

Fred

[Jeeptechfred]

Low compression definitely also can cause misfire at low rpm