Bottom End Rebuilds

im starting to tear down the bottom end on my block and im looking for a little advice. im not upgrading anything in that part of the motor and only wanna change the bearings, hardware, and piston rings. i might have to change the pistons and rods, but im not gonna upgrade them. so, that leads me to a questions. do i have to have the block shipped to a machine shop if im only installing new oem parts? if the cylinder walls are in good shape and theres no damage to the internals of the bottom end, i should be ok to install new oem stuff and reassemble it to stock torque specs correct?

If you are not upgrading anything or looking for power soon you can tear down and rebuild without any problems. If you tear it down and there is excessive wear (Digital micrometer is your friend) then I would have a shop clean it up, you may have to change your rebuild kit to accommodate bigger bores on the cylinders and the main bearings (correct me if I am wrong)If your block still has the 60 degree oil catch marks on the walls you are in really good shape and it safe to presume the rest of the motor doesnt have heavy wear, just replace with fresh. If its a CA20E and it has excessive wear throw it away.

hey julie you rebuilding a VG or CA,

I have standard CA bearings if need them.
there were for my CA18ET rebuild, but i went another route that was cheaper..

"do i have to have the block shipped to a machine shop if im only installing new oem parts? if the cylinder walls are in good shape and theres no damage to the internals of the bottom end, i should be ok to install new oem stuff and reassemble it to stock torque specs correct?"

No you don't but its good idea.
you can rebuild your own motor with tools you can buy at the autoparts store.
if this is your first rebuild Buy the Nissan Book. and take your time read everything.
i can't be any more explicit on this.

installing OEM stuff: that would depend on your budget?
total Seal piston rings, CP pistons, have the rods shot peened,
have the crank checked for heat marks
have the crank micro polished and rebalanced w/o flywheel.
have the oil holes in the crank beveled and opened up before polishing.
i don't recommned knife edgeing beucase of the expense.

before you take the motor apart get some plastic gauge and check your bearing clearancs.
this will tell you if you need to have block line bored if the real off, again you will need the serivce book for this.

engine rebuilding is an enjoyable experince if you take your time.
if you rush its a nightmare.

cheers

you'll have to get a hone so the new rings seat. I did mine a while back with no machine work, just a hone, new rings&bearings, plastigage, a couple of mics(inside & out), and the FSM . I don't know about you but it was my first bottom-end, So Far So good(knock on wood),passes emmissions, has compression, and doesn't burn oil. Mine's a CA20 though, no major loss in the event of catostrophic falure I figure. You may feel different about your DET though.

+1 on the honing. If everything else is within spec (a plastigage or micrometer set will tell) then this is the only machining type work that you must do. If you don't hone the cylinders your new rings will not bed properly. You need to remove the glaze on the cylinders. Some of these tools could probably be rented from the autoparts store.

Aside from that, what everyone else said. Follow the FSM thoroughly, don't rush, ASK LOTS OF QUESTIONS if you are not sure about anything. Take pics and use little plastic bags when necessary. Note which parts belong to which cylinder, and which way was facing forward originally.

If you replace the pistons, then they will likely have to be oversized because the block will need a light bore to get everything straight. A motor should always be bored to match new pistons. Be sure if you take it in to have it bored that they do it proper with a block plate (unsure of the exact term) that bolts on to the block using the stock head bolt locations and stiffens up the block so it doesn't warp under the heat and stress of boring, and it needs to be done in the order the FSM dictates.

If you are not familiar with the plastigage thing, I can explain it, its actually a very cool and simple way to check tolerances. Not the best on a high-end build motor (thats where micrometers are good) but will work just fine on a decent street engine (factory recommended procedure). Just make sure as you disassemble the engine that the bearings stay in their original locations and don't fall out on the floor.

Cleanliness and proper lube is essential when reassembling, but getting it tore down and the right replacement parts chosen is the first part.

Ask lots of questions biggrin.gif

Don't buy Total Seal rings. They're a kent to work with. If they don't bed in, you've fkd a set of good rings. Use the ones that come with the pistons.

Get the block chemically cleaned.

Use decent bearings, like Clevite, or King.

Get the oil drains in the block (from the cylinder head), and in the cylinder head de-burred to improve oil return to the sump.

Leave the OEM rods if you're staying under 200kwatw. They'll be perfectly adequate.

The bores will need to be measured after the block is cleaned, to detirmine what size pistons you will need. You may find that you will need to go to oversized pistons necessitating that the block be bored to suit.

All the best.