Thread: How To: Change rod bearings

I believe this is for wear purposes that are factored in. From what ive seen in the many i have done is all the bearings that have come out are 00, But a highly respected machinist here stated that nissan used such tight tolerances with their bearings that is why there are different grades. He said you could use basicly any grade number and be just fine but if you want them to be perfect then use the correct grade. Most parts stores that sell aftermarket bearings such as acl and clevites use just a standard grade. The difference in thickness between the grades is very very close to nothing. I mean it only specs up that much closer to the given spec.

There is basicly no other company that does their bearings in as tight of a tolerance as nissan did with many of their motors. But again i would still use the correct grade to where you know you have it right.

Oh and screw the dealership because most of the time they dont know jack. Save yourself the trouble and buy them from Greg from Gspec performance. Cheaper and you will have them quick.

Pretty much right on with this statement. The bearings from nissan do not have the code stamped on the actual bearing. The box itself has the last digits of the part number that coincides with the color/size. Honda and Subaru have the same system also.

Tolerances are very tight and are ment to be like this for longevity. However for performace you don't want them factory spec. I went .0025" on mine and .003" on the mains.

Also, if you use arp rod bolts on stock rods and expect the same clearances without distortion you are greatly mistaken.

Question on the crank spinning. When you say spin by hand do you mean with a ratchet in your hand or literally just with your hand. I changed my rod bearings today, however there was some resistance to overcome in spinning the crank. I don't believe I could spin the crank just with my hand on the crank pulley.

It felt like on the upward strokes their was resistance to overcome and then on the downward stroke there was much less resistance. Also while spinning the crank is it normal to hear like air release type of sound? I assumed this air realease was a result of the compression the pistons were making in the cylinders.

Also something else to note. I had the crank girdle off while i was changing my rod bearings. I hope having the crank girdle off wasn't a serious error.

sounds ok but If you pull your plugs you shouldn't get much resistance and you could turn it by hand (or a small ratchet) if the crank pully is still on.

should be able to spin by hand

Ok I have some data to compare with others. I filled up my long block with the required oil amount. I was thinking maybe the resistance was from too little oil put down on my rod bearings when I installed them.

I cranked it a few times to get the oil flowing. I did feel like my resistance problem improved. Next I went ahead and put a bar type torque wrench on the crank pulley to get an idea of how much resistance I was encountering before the pulley decided to move.

I tested with the spark plugs removed from the head. On the more resistant stroke I was reading about 20-25 ft lbs, on the lighter stroke I was reading about 5 foot pounds.

If anybody has the ability to get readings from their own long block I'd appreciate you getting back to me with your data. My own engine is on a stand right now without a flywheel bolted on and without the drive belts attached. I figure this will cause some difference from motors that are already in cars. I tested without the spark plugs in head. However any torque readings I can compare to would be great.

i'll give mine a whirl when i get home. Also on a stand with no flywheel, so should be a good comaprison.

^^Cool. Thanks Man I appreciate that.

...One important thing you left out... If you can not slide the cap on and off the threaded portion of the rod bolts, without bearings, your rod ID is probably stretched and you are taking a huge risk or running a round bearing in an oval shape, which is what COULD happen if you spin bearing.
So once you "TAP" on the rod bolt end to get the Cap to seperate, you should be able to slide it back on until its kind of snug, doesn't have to be too much, but if after you remove the cap, it does not easily slide back onto the rod bolts, you should be able to get the cap down to about 1/8 inch before it hits the Rod. Also, if you have scratches on the crank, if your finger nail doesn't catch when you pass it over the crank, you're good to go, if it does, I would recommend taking some VERY VERY FINE Emory cloth, (Sandpaper on a fabric strip) and lubing it up and basically wet sanding until its smooth again, you won't take off too much, but just go one size up, meaning thicker. I've done this procedure 3 times on honda B-Series VTEC engines taht rev to 8K RPM, and have had zero issues. Last one I did was a B16 for a friend and he did the right thing by calling me up and having me take care of it before he did some real damage.

The thing to be wary of is if the last rod bearing failed or spun, suggest removing oil pump spring and shim it to give more pressure, as we all know the Oil Pump replacement with engine in car takes up too much time. Have never had to shim one, but pretty much that large nut on the oil pump, there is a spring in there.

I'll do an experiment on my B13 SR20DE before the engine goes out since it does have a slight high RPM rod knock, just not too loud yet. Compression is 180 across the board though, so I might do a documented work on it in the next month or so. I already have a DET sitting at my shop, just waiting to sell a bunch of Honda stuff and a stupid Corolla to fund it.

Good job guys this really help me out thanks