Last year I purchased a 1996 F-Superduty with a 460. The seller stated the engine had a lot of blow by and rattled under load. He replaced the main bearings (for the rattling) and unhooked the oil vent line that runs into the air box (says the filter was getting plugged with oil). According to him, it still rattles and has excessive blow by.

On the way home, it did rattle, not always though. When it did, I would let off the gas and it would stop. Sometimes when I pressed the gas pedal again, it would immediately start rattling again sometimes it wouldn't. The noise sounded like it was coming from where the engine/ZF5 speed mate. Hard to tell, but that was my best guess. Never drove it again after that day. But other than the noise, the engine ran very smooth and quiet. Almost like a new motor.

Last week, I purchased a 1997 F350 4x4 (a parts truck for my other Fords). The seller claimed the 460 was a Jasper rebuilt (30,000 miles), but hadn't been ran in 3 years. When I started it, the engine shook like crazy, but settled down to a constant miss. I also noticed the muffler had been blown out due to backfire. After draining out the old gas and adding fresh gas, the motor ran better with only a slight miss. A quick look reveled it could use new cap, rotor, wires and plug.

So, what would you do? Should I preform any test on the F-Superduty engine or just swap it out with the F350 engine? What kind of tests? Compression tests or leak down tests?

What kind of tests should I do to the F350 460? It's only a parts truck so I hate to spend time and money on it. I figure if I put this engine in the F-Superduty, I would change the intake, head, and oil pan gaskets at least.

I really need a logical game plan on the engine issues. I plan on using the parts truck to convert the F-Superduty to 4x4.

 

If the F-SuperDuty has new bearings, the rattle is likely spark knocking from the distributor being incorrectly timed. Pull the spout connector, verify the timing is 10* BTDC. Years of spark-knock likely hammered the pistons and piston rings, however - leading to excessive blow-by and low compression.

You should do a compression check on the F-350 460 and verify the engine is in good health. If the compression checks out, the misfire could be from bad gas, bad plugs, faulty injectors, etc...

 

If the po replaced main bearings he likely didn't fix the problem....it could very well be a rod bearing.

Is this a "knock" or a "tap"?

 

I can't remember off hand. I'm hoping to start on it later this month, I'll be sure to report back what I find out.