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I have a 1991 Mustang 5.0 engine that is being put into a 1964 Ranchero. The EFI has been replaced with a 4bbl carburetor and matching intake manifold. I have followed all the EFI to carb recommendations and so far everything is working out O.K. The donor engine was in pretty good shape, although I never heard it run. I did a mild rebuild which included a valve job, replacement of the rings, rod bearings, and a new oil pump, etc.

I am by no means an expert engine mechanic. So being a little nervous about putting the engine in the car…then trying to start it, I built an engine test stand so I could run the motor (and fine tune it) out of the car. I got the engine started and shortly after warm up, I could hear a “tapping” sound coming from around the rear passenger side of the motor, especially at idle. A mechanic friend, using a stethoscope, isolated the noise to the valve train of the # 4 cylinder, and considered it to be a possible collapsed lifter (I didn’t replace the lifters, pushrods or rockers). We tested our theory by removing the rockers and pushrods from #4 and running the engine with 7 cylinders….….the sound was gone! So I drained the coolant, removed the intake and replaced both #4 lifters and reassembled. Much to my dismay, the sound is still there!!!

Still determined to figure this out, I took an old valve cover and cut the top off so I could hear and watch the engine run. It seems to be oiling fine (I added a quart of Rislone) and the sound is coming from the #4 area. I even switched both rockers and pushrods with #1 to see if that might be the problem (bent or warn components), but no change.

So here is an interesting situation: While the engine is running, I’ll loosen the intake rocker of # 4 completely (lots of rattling) then retighten….the ticking is gone! But comes back in about 30 seconds. What’s even more interesting is if I remove any one of the 8 rockers on that same side while the engine is running, then retighten, the ticking is gone but returns in about 30 seconds! It seems like an oil issue, but I can’t figure this one out. Please help
 
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