First rb30 build, need advice

[Rileymax]

Just wanna preface this and point out I'm a mechanical fitter by trade but have had very little rebuild/machining experience, but I am keen to learn, hence this project. Bit of a write up here so bear with me, just want to make sure I do this right 

I've got an rb30e currently pulled down. Planning on putting a 25 head on it and running it in my s14. 

Not chasing huge power so I'm just going to try get away with factory bottom end for now. 

Started measuring the crank the other day, realised my budget daytona micrometer set wasn't up to the task (surprise, I know). They only measure to 0.01mm but the Nissan specs are to 0.001mm. Anyway, I started measuring anyway and came away with the mains being inline with the oem spec, as well as the big ends, except for no. 5. I consistently got a measurement of a hair over 49.96mm, where all the others were pretty spot on 49.97mm. The lower spec for grade no.1 is 49.961mm.

I'm getting access to some better gear my next days off to double check everything, but in the case that the big end is right on that bottom spec, is it pretty much just a case of straight to the machine shop for machining and oversized bearings? I understand I need to measure the tunnel as well to work out my oil clearance, but it's the different grade bearings in the manual that are confusing me. What is generally the process when one journal would still technically be in spec, but in a different grade? 

Thanks for coming to my Ted talk

[Duncan]

Well, if necessary you can mix and match bearing grades, that's what Nissan did from the factory (on rb26 at least)

However, the overall problem is no matter what you measure it as, unless you are totally happy with the result and put it together it will be going to a machine shop who will redo all the measuring anyway.

I'd suggest putting aside money for bottom end machining, and let the machinist decide the main and big end bearings. Also, you need suitable pistons for the hybrid engine and going oversize on the bore is the best way to ensure good clearances on an old or unknown engine.

Head is even worse, its worth getting that done while it is apart too. Certainly stem seals and cleaning and bleeding the lifters while it is apart is a good idea with an old head too, but also checking valve seat and cam tunnels

[Rileymax]

Cheers for the reply mate 

I have no issue running standard bearings if everything is in spec, I just wasn't sure in regards to the different journal specs, having never ordered oem bearings, I didn't realise they can be ordered individually. 

In regards to pistons, basing off the rb30dohc.pdf a lot of people refer to, I thought I'd be okay with rb30e pistons? I understand they'd be a reasonably low compression ratio but what I read says it's not an issue? If that's not correct though then yeah, I may as well just send everything for a holiday at the machine shop I guess. 

The head has already had a bit of machining work done to it, I'm yet to find out the extent but I'm buying it off a pretty reputable performance shop in town so it should be pretty good.

[Duncan]

I don't think you can order the bearings individually aftermarket, to my knowledge they come in sets (noting a machine shop might be able to mix a set for you).

But more importantly, while a "slapper rb30" has been a thing over the years if you want a cheap engine, it really is not the right way to go if you want a half decent result.  In the end, if the engine is apart you really should do it properly with decent CR pistons, careful measuring, replace head and main bolts with studs, head service and probably cams, bigger oil pump and improved oil returns, baffles in the sump etc etc on the basis that you are probably going to want it to be a decent performance engine way day. Yes it all adds up so you need to be sure you are ready to go that way, the alternative is a disappointing result that you end up having to pull back out and do properly one day anyway 

[Rileymax]

Definitely aware it adds up, I've had work done before, just never attempted it myself to this depth. Stock pistons and rods are fine for what I'm chasing, I was just a bit unsure on the measuring side of things. Not looking at making any big numbers or looking to build a track car, just have a rolling shell that has been sitting for too long. 

Pulling the engine and forging it later is the goal, hence why for now I'm just trying to figure out if I can get away with minimal machining so I can get it in the car and focus on the other aspects of the swap. Regardless it will get oil mods and the works anyway. 

 

Cheers for the replies mate, appreciate the advice 

[GTSBoy]

Just be prepared to buy more than one set of bearings and use as required, putting the leftovers on the shelf. Normally this is the sort of thing that an engine builder would do that you don't see happen. They figure they'll use them one day down the track. You might never.

 

[Rileymax]

Ah right, too easy then. I have a mate who builds some pretty wicked Hyabusa engines for drag racing and he gets his bearings direct from Suzuki and just orders what individual bearings he needs so I wasn't too sure if Nissan did the same thing (haven't had the chance to have a chat with them) 

Thanks for that mate

[GTSBoy]

You wouldn't be buying bearings from Nissan. Surely? You have to replace them, so surely you'd be looking to buy the very best bearings available - which would suggest something aftermarket.

The Suzuki example is not relevant - because a) motorbike, and b) Suzuki. The reason I bought Suzukis for my kids is that I have way more respect for the engineers of Jap car companies that also make motorbikes than I do for those that do not make bikes. The engineering required to make a decent bike is substantial, and it spills over into the car operations.

Nissan do not make bikes.

[Rileymax]

Great, thanks