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I just inherited a '79 Jeep Cherokee, while I don't know anything about Jeeps, and never driven one in my life, I love this one and due to the circumstances in which it became mine, I won't ever let it go. Anyway, its in pretty good shape, but it did sit for a couple of years. Its got the 360 in it and has an edelbrock carb. Its running really rich, but when its leaned out it damn near won't run at all. I've tried adjusting the ignition timing too (the book says it should be 6-10 degrees advanced, it was set at 20) but haven't had any luck there either. It doesn't ping at all (even though its still set at 20 degrees before TDC). Question is: is Edelbrock a good/commonly used carb for this motor? (I have one on my '78 F-150 and it works beautifully) I'm thinking I may need to bring it to a shop and have them put it on the scope?
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The 79 Cherokee is the SJ series Jeep Cherokee. A full-size SUV produced from 1974 through 1983 by the Jeep division of American Motors Corporation (AMC). It was similar to the Wagoneer that was originally designed by Brooks Stevens in 1963.
The 360 (5.9L) engine is one of the good AMC V8 family engines. 304, 360 and 401. They all shared the same basic block and shared many other internal parts. When they got a lot on miles on them the timing chain would stretch and sometime jump a tooth. They were famous for keeping on running even when abused and neglected. They didn't run well with the timing off a tooth but would still run for years like that. A problem with this is that chain would get so loose and the engine would keep on running that the sloppy chain would saw a hole in the front aluminum timing chain case. One tooth off would easily account for your ignition timing being 20 degrees off.
I really don't think a scope would tell you much about that engine. An old adage with some merit goes. "if it sounds like carburation, it is probably ignition". and "If it seems like ignition it is probably carburation". You can check for timing chain being off by removing the valve cover over #1 cylinder. (#1 being the cylinder closest to the front) Turn the engine to the TDC marks (might be 0 and not TDC) on the front pulley. Either both valves will be fully closed or be teetering between exhaust closing and intake opening. If the valves are both fully closed, rotate the crank one full turn till the valves reach the point where both are still slightly open. If your chain is off the teetering will not occur at TDC. Replace the chain if you take it apart.
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Thanks for the tips, much appreciated. The truck has 130k miles on it, but I also know the motor was rebuilt in '02 at 115k. I don't know to what extent it was rebuilt, or really any other details about the rebuild. The Jeep was previously owned by my father-in-law who was known for being meticulous in just about everything he did, but the records were all kept outside of the vehicle so we weren't able to recover them.
I'll check into the timing chain issue, thanks again!
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