Building The Bottom End Up.

[MBS206]

Hey guys,

I've got an RB25/30DET in my R33 at the moment,

Problem being, it decided to spin the big end bearing.

What I want to do is pull it all out, and rebuild it.

The biggest problem I have... I've never rebuilt an engine before.

If following the manual, and doing everything slowly, are they really that hard to rebuild?

Are there any special "tricks" to rebuilding the bottom end of an RB30?

[JCaSs1001]

by rebuild do u mean assemble??

everythings gotta be measured up and prob machined depending on damage dont forget.

[Dale FZ1]

Once you've determined the cause of the run big end, and employed a remedy for the rebuilt/replaced bottom end so that it does not happen again, the actual build is fairly straightforward.

The real work is probably in ensuring your clearances / tolerances are right before you screw the thing together.

[MBS206]

The motor will be heading off to the machinists for all the regrind of the crank, and a rehone on the block and a bore to match the cylinders.

In respect to the cause of dead bearing. It's appearing to me as a mixture of oil surge, and an over rev (Should have stayed up in 3rd gear instead of attempting to accelerate in 2nd, as 2nd just spun the wheels instantly).

So I'll be looking to increase the volume of the sump, as well as baffle it (And a bigger oil pump).

Now, by ensuring clearances and tolerances, you're talking plastiguaging the bearings etc?

I've never done that before, so I have NFI on how to do it. Any one care to elaborate for me?

And by build, yes, I mean assemble.

Will be getting all machining done off at a workshop that specialises in it.

[W0rp3D]

Check out this link http://www.skylinesaustralia.com/forums/Oi...ui-t110680.html

[r33_racer]

If the machine shop is good and you trust them, you wont need to plastigauge or mic up the clearances. Should be just a matter of assembling the motor.

Though it would be good practice to double check everything. Im pretty sure the nissan workshop manual explains basically how to check it all???

[bluegts]

I dont get why spinning the wheels in 2nd contributed to a spun bearing. Unless you didnt have a rev limit for some reason, even then I would have thought something else would break before a bearing

[TiTAN]

too many revs + not enough oil/oil pressure and say goodbye to one or more bearings.

[MBS206]

I dont get why spinning the wheels in 2nd contributed to a spun bearing. Unless you didnt have a rev limit for some reason, even then I would have thought something else would break before a bearing

From what I've been told, you can spin a bearing from engine picking up revs far too quickly, with not quite enough oil pressure.

Basically, the rate in which this engines revs when it breaks traction, under full boost it doesn't just "rev up" it just simple jumps from 4000 RPM to the rev limiter... Jump in RPM like that, but oil pressure lags behind slightly.

In regards to this build, I've found the person I'm getting to build it. And very confident in it being done right. Now to just get up enough cash for parts and what not.