I tore down my 440 and would like to try to re use it as it ran pretty well when taken out 10 years ago. Its been on a stand filled with oil. I was going through the bottom end looking at the bearings when I noticed 3 of the pistons are very tight on the connecting rods. The piston is so tight that It takes a lot of force to move the piston, not free and sort of floppy like the other ones. What could have caused this and any tips on getting it free? will it need to be pressed off and back on? I havnt tried using any penetrating oil or anything like that.

You will at the very least need to have the rods reconditioned/resized. Do not attempt to press the pins out of the rods at home. This is stock stuff correct?

Yup, stock rods, etc.

These are stockers so they do not have a floating pin. Resizing the rods will not be necessary and will cause problems if you do - and stock pistons do not have retaining clips for the pins.

The pistons could be galled. If the plan is to re-use those then you'll have to clean them up with some emery cloth if the galling isn't too bad. Could also be the pins rusted in which case they'll need to be replaced.

Before I did anything else, I'd hit them with WD40 and start moving them back and forth and side to side. Any rust will desolve into the oil enough to indicate if that's the problem. And who knows, they may just break loose and be fine.

Since you havent tried anything and its been sitting
for years I'd spray them first with wd-40 or something
and see what happens

Thanks guys, Ill try to spray them down first, they are not completely locked, just tight. Great feedback as usual!

Well, i was messing around with the pistons last night, sprayed them down with penetrating oil. After moving the rod back and forth, I noticed that the entire wrist pin is spinning in the piston, and the rod seems stuck to the pin.

Are the pins pressed into the piston and not supposed to move? Even if I free the pin from the rod, is the piston now junk? Ugh!!

Yes, I already mentioned that but to be perfectly clear, the pins float in the piston and are pressed into the rod. That's why you can't resize the rod's small end.

Got it! I was thinking the exact opposite. This gives me some hope. Having said this, I sprayed the penetrating oil on the wrong part. I will hit them again where the pin contacts the piston.

Yes, since I had to check all of the bearings (main and rod)I had to unbolt the rods from the crank. I then slid each piston up in the bore (off of the crank)and moved each rod to ensure it was free w/o binding. 5 out of 8 were nice and floppy, but 3 of them were not.

Im hoping it was because the motor sat for 10 years and its just gummed up.

When the piston heats up it expands and those tight pistons will be just fine. That's as long as you can move them by hand.

That's my

R.

Warm = looser, cold = tighter. What temp is the piston when the engine is running?????

We know that aluminum has about twice the rate of thermal expansion as steel, so the piston hole grows bigger faster than the wristpin.

It's my opinion that you have nothing better to do so are entertaining yourself by chasing your tail. But I could be wrong.

R.

Yes, I realize this thread is 6 years old but after basically tearing the top end of this engine down a few times I think this issue is the source of my engine noises. After posting this thread, I brought the pistons/rods to the machine shop and asked them to disassemble, and loosen them up a bit to match the others.

I always had the tapping sound since I put the engine together. I didn't take it to the track yet or have it dyno'd so I don't know if this issue is impacting performance. I did swap out the cam, lifters, rockers and push rods (measured for custom length) and nothing changed this sound.

I then started pulling spark plug wires on the cylinders that had the tight pistons and wouldn't you know it, the noises went away!! So is it reasonable to think that now the pins in those rods are now loose and contributing to these noises?

I really don't want to pull the engine out until winter when I have more time, what could happen here, anyone know from experience? I'm guessing it will get louder and louder until BANG!

This engine is basically a place holder while I plan the next engine build (will be done by a pro, not me lol)


https://www.youtube.com/watch?v=rFh6mxFDMrE

Piston slap., wrist pin noise and exhaust gasket leaks sound a lot alike, I can't tell what your noise is on here, sorry
As far as making the noise your hearing go away by you pulling the spark plug wires off the bad cylinders makes me think it is piston slap your hearing
Does it get louder or quieter when it is warmed up? If quieter it is probably piston slap
Is there oil on that spark plug?

Unfortunately, the noise is the same regardless of cold/warm, RPM, etc. Pretty much there all of the time.

To me, that noise sounds like tappet noise, like one or more of your hydraulic lifters is collapsing.

I was hoping it was the tappets but I have changed everything in the top end at least 2 times w/o any difference to the sound. 2 cams, 2 sets of tappets, 2 sets of rockers including stamped stock and adjustable roller, 2 sets of push rods as well.