304 mystery

I am creating a new thread with this because it's so darn strange, I thought everyone might get a kick out of "solving" it.

Background (please be patient):
I purchased a 304 out of a barn that supposedly had a new cam and lifters installed (it did, I saw the boxes they came in and inspected the parts). The engine also had long-tube fenderwell headers attached. The numbers on the cam indicated a pretty mild "RV" stlye cam, nothing radical. My origonal 304 was a '72, but this one was a later year. The engine did not have an intake on it, and had gotten some water in it at some point because there was rust on some of the surfaces in the lifter area. The rockers were not tightened down when I got it.
I installed the engine, and primed the oil with a drill until oil started hitting the ground from the rockers and fired it up. I was forced to drive it to work the next day.
Here's the result: 6 bent pushrods - 5 intake and 1 exhaust. Okay, so I replaced the bent ones with ones from my old engine, checked lift carefully, and fired it up again. My theory was that I had frozen lifters, but they were probably good by now.
Result #2: Only 2 bent pushrods, and three lifters that chatter (different ones than the bent pushrods). These lifters may or may not have been chattering all along, I don't know for sure.
In a fit of desperation, I pulled the intake, took the liffters with bent rods apart and verified that they worked. All good. New pushrods, fired it up.
Now, I don't have ANY bent rods, but still have a few sloppy lifters.

And finally, here's my question: If it was frozen lifters, why only Intake? and ONE exhaust? And why not ALL the intakes??? If the lift was too great, why am I not still bending rods? And WHY would I have a few lifters that still won't pump up? Rust in the oil lines? The lifter next to the noisiest one pumps three times as much oil out as any of the others, so maybe it's getting it's twin's share? At this point, I have fussed with this thing until I just don't give a damn. I'm just curious.
Want to know the SICK part? Right now, I'm looking on ebay for another Jeep just like mine, only one that runs. I truly am ill. It has to be illness, I'm too young (barely) for senility!

 

Steve,
The lifters are definately new, AND they are full of oil. I'm just baffled at this point. I've never had an engine do this, and I've torn so many old mopars apart, I've lost count. Of course, it's been a while, maybe too long.

 

Just a dumb thought - you sure it's a 304 and not a 290? 290's shorter deck height would let the 304 pushrods bottom the lifters. That'd bend the pushrods, make noise from the lifters, etc.

That or make sure the valve lash is good for hydraulic lifters. Zero-lash plus 1/4 turn. Also, make sure the oil passages for the rockers/lifters aren't plugged. I know you say the lifters are full of oil, but is that from the install? Also, you don't pump up the lifters with oil for initial startup. Just give them a soaking in some motor oil - you don't depress the plunger and fill the cavity with oil.

 

Dummy,
I checked the castings on the engines, and both the old one and the new one are 304. Valve lash on the new one is non-adjustable, although if I get desperate, I'm gonna shave some off the aluminum off the "bridge" on the loose cylinders! It's the combination of SOME of the rods bending, combined with SOME of them being too loose that is throwing me. I suppose the whole thing could be chalked up to stuck and/or bad lifters, but they weren't in THAT bad a shape!

 

I'd still suspect the rockers. The AMC rockers are pretty lousy, with cast aluminum pivots that wear rather quickly. Check yours and replace them if they're worn badly. That would let the pushrods flop around a bit too much and could contribute to your noise and the bending.

Also, only sock the rocker arm retaining nuts down to 20lb-ft when tighening them.

 

Further note:
Well, I drove it around today, just to get to enjoy it a little if it IS going to blow up or something. I then pulled off the valve covers and discovered NO bent rods, but one bad lifter, one broken bridge, and one cracked rocker (I knew about the rocker and bridge, though). So if the thing can stand slapping the bad lifter around until new parts come in, maybe I'll be okay. The whole thing was STRANGE, though! By the way, do you know HOW MANY times you can reuse the metal intake gasket? I'm up to three now with no leaks or anything. Thank God for RTV Blue!

 

When you have a chance you might look at the valve springs when a valve is open to see if the spring is totaly colapsed. Maybe with a little more lift, a lifter that is a little taller you are getting too much lift.

 

just my 2 cents, when i was putting my engine together, i ordered new lifters. when the parts arrived, they were not all the same height. (as if someone had mixed up the box to complete a set) they all looked the same except when you lay them out on the table, some were taller than the others

 

But did they work?

 

no i refused the order and had them order another pack. when the new set came in, they were all correct height and matches my old ones.

 

My dad has a 58 chev biscayne car that after long periods of storage, 2-3 years, on the drive home it would push the rocker stud right out of the head! The valves would get so sticky-rusty-or whatever that it would put that much stress on the valve train trying to open the valves. I know this was a 283 chev v-8, but I'm sure this could happen to any engine after a period of time. Just a thought.