Rb26 Rebuild

[Stoney85]

I'm sure this has been covered numerous times, but I'm unable to easily find what I want to know.

I'm about to undertake a rebuild of my R33 RB26 after a piston ringland failure, running 320rwkws and a stock old bottom end didn't mix.

I WILL be tuning the car again and running a wideband before any power runs etc will be undertaken. But all the bolt ons and headwork will stay the same.

The main acc's include a ViPEC ECU, GT3582R, Tial 60mm, 6 Boost manifold, 750cc injectors

I have in my build the following parts

Nitto oil pump

R34 crank, balanced and prepped

Eagle Rods

Tomei cooling channel 87mm pistons and rings

ARP studs throughout

ACL race bearings

Ext head drain

Oil feed restrictor

I'm reusing the stock head for now, but do have a JHH built head, that had a valve failure and needs a rebuild in the future.

What I want to know, is what block prep work, or any other hidden secrets people perform on their rebuild.

I've done a few old Datsun L series rebuilds, and an SR build, and the L series had a book available which mentioned things like deburring the blocks internal casting marks, polishing/enlarging the oil drains and even paqinting the internal walls for better oil drain.

With that oil pump and oil feed restrictor, can I get away without fitting the ext head oil drain or is it a must?

So is there anything like that people do to the RB26, on top of using the good parts in a rebuild?

[GTRPSI]

External oil drain (breather on rear) is the out of date way, people have stopped doing this.

Its about equalizing sump and cam cover pressures so the oil can flow back down, so a breather hose from above the oil level of the sump to the cam covers is one way, another way is to simply weld some fittings above the oil line on the sump and vent blowby straight out to a catch can.

Enlarge the oil drains in both the head and block.

Fit oil restictor to the block.

Use a long nose drive collar for maximum oil pump engagement, use a good aftermarket pump or at least a stock pump with gears.

Or better still, read the oil control thread, first few pages and maybe the last 10-20.

[Stoney85]

The oil head drain setup I had been using on the old built head, drains to the rear turbo drain fitting on the block, so I'd assume that its higher than the oil level, so it should do exactly as you say, equalize pressures.

The R34 crank is already the long nose setup is it not? and i'll be using a Nitto oil pump.

I'll read into the oil control thread, thanks

[djr81]

Do the head clearance around the cam lobes for when you get bored and want to put big lift cams in.

[Stoney85]

MY JHH built head has that already I'm pretty sure.

[GTRPSI]

The oil head drain setup I had been using on the old built head, drains to the rear turbo drain fitting on the block, so I'd assume that its higher than the oil level, so it should do exactly as you say, equalize pressures.

The R34 crank is already the long nose setup is it not? and i'll be using a Nitto oil pump.

I'll read into the oil control thread, thanks

Yes all the turbo drains are above oil level.

R33 and R34 cranks are all long nose.

Nitto makes a good oil pump, i went tomie because its externally adjustable.

If you need to adjust the oil pressure with the Nitto pump, its a engine out job, the tomie one you just remove a plug on the outside of the pump and add or remove shims.

[Stoney85]

That is another question I wanted to ask, in regards to being able to adjust the oil pressure. Is there a recommended spring rate to run? Run it at stock pressure or higher?

I'm slowly getting through the 70 pages on the oil control thread and haven't come across that topic yet.

Thanks already.

[GTRPSI]

10psi per 1000 RPM is what your looking for in pressure.

The spring/washer setup will depend on clearances and oil weight run. (and temps reached)

So if you have a 9000 RPM redline, you want 90PSI (or a bit more)

[Stoney85]

Thanks for that, I think i'll stick with a stock RPM ceiling for now, keeping the standard head for this rebuild.

The bottom end I'm doing properly as I have all the parts on hand, finally read that oil control thread, very handy info mixed in with the same questions asked 1000 times over and over.

I'm currently cleaning the block of any honing material leftover, cleaning all the parts I will be using, have sourced a set of accurate scales and will be matching the balanced rods and pistons to get the most even weights throughout.

Flexigauge material has arrived to check clearances, rings are here too, so setting ring gaps is next.

I don't have an RB26 rebuild workshop manual, so that's my next document I have to find, while the info is available everywhere, I'd rather have some genuine Nissan specs on paper beside me. Also need to source ARP stud torques, then there is what assembly lube to use and so on.

Got some homework to do tonight.

[GTRPSI]

When cleaning the block, knock out the front and rear oil block bungs and use a rifle cleaner kit with the long rods and a variety of stiff brushes in different diameters, be careful as the brass brushes can and will lose hair and can leave bits of brass behind.

Run a self tapping screw into your blocks oil restrictor, put a old adjustable wrench under the screw head and knock out the old oil restrictor, for the rear plug drill a small hole and do the same.

You would be surprised how much junk sits behind the factory oil resrictor, id never just knock a smaller one like Tomie advises over the old one if rebuilding a engine, especially a engine that may have spun a bearing previously.

[Stoney85]

I believe the block already has a smaller restrictor in place, when it had a top end refresh not too long before I purchased it (mercury motorsport did it) but I have a 1.5mm here to fit anyway, maybe i should have gone to a 1.25mm after reading the oil control thread, but I dont plan on tracking the car or putting it in any driving conditions where it sits at high rpm for extended periods of time.

I can see why fitting the new restrictor over the old one is done, purely because its easy, but I'll do what you mentioned, and hopefully there is only one that i have to remove.

Fitting the new one, does it have to sit flush with the block or would it matter if its sunken at all? Cant see it being an issue, but I thought I'd ask anyway.

After the block was machined and honed, it did have an extensive hot wash as I instructed, and i went through a few toilet bottle brushes cleaning the bores or any leftover hone material, but will check and clean the oil feed once the old restrictor is removed. It was a super clean motor when I dismantled it, and from what I was told by Tessa, It was a low km motor when they sourced it, and i'm rebuilding it not from a spun bearing but a damaged piston.

Still waiting on a few parts to arrive, but I checked all the ring gaps and nothing needed adjusting, specs on the tomei rings say between 0.18-0.35mm, I was getting 0.28 on all top rings and 0.31 on second rings, so i'm sufficiently happy with that, oil ring gaps are between 0.18-0.75 and were at 0.55.

Weighed all the Tomei pistons and Eagle rods, and all are within 0.5grams of each other, so i then proceeded to fit all the rings to the pistons after a good clean, and the pistons to the rods.

Put the crank in to check big end clearances and happy to report all are pretty much exactly on 0.05mm gap according to the flexigauge strips.

I'm pretty much ready to assemble the bottom end. Considered doing it last night, but wanted to tackle it all at once with a clear head.

[GTRPSI]

Restrictor is OK lower than the deck, im running a 1.1mm on most performance builds.

I also get the hot wash, then go through all the oil passages with rifle cleaners and pull more gunk out, you would be surprised what a stiff brush can release that the wash didnt in those small hard to get to passages.

Ring end gaps are related back to the bore width, fuel and boost you will be running, did the paper work explain that? Ring manufacturers explain that in all the ring packages ive used.

0.18mm to .35mm is a huge variation, double check your paper work from the ring supplier, they know whats best for their rings, follow what they say, quite often is X amount per bore inch of diameter.

Different manufacturers and materials have different expansion rates.

Remember mains clearances are a little bigger than big end clearances, again X amount of clearance per inch of crank journal width.

[Stoney85]

The bore is machined to Tomei 87mm specs and the ring clearances are set off their specs too, the bore clearance is smaller than most at 0.05mm or 2thou. The tomei specs are pretty bland in their description though.

My bad on the big end clearances, I meant to say main clearances, haven't check the big end specs yet, but these rods and this crank have been together before on a very high hp motor built by JHH, so i'm confident they are correct, but will check them anyway.

Thank you for your help.

[Stoney85]

Bottom end is assembled now, clearances are all great, still waiting on the restrictor to arrive though before the head can go back on.

Seeing as it was only done not too long ago, the head surface is pretty clean and using a cometic MLS before, there isn't much to clean off, but does anone have any tips? before i delve in with a razor blade, will try some degreaser and rag first to see how much comes off, just would much rather not scratch the mating surface, and its too clean to need another machine, i did get the block decked, but it was ever so slightly the original stampings are still evident, something like 2 or 3 though i think.

I've got too much going on right now.. This rebuild for my R34, restroring a MK2 Jag so it runs again - ignition, fuel system, brakes, Just got an E28 BMW as well to clean up and sell, and my daily E34 BMW I just welded up and fitted BC racing coilovers to as the original stuff was dead.

[GTRPSI]

Have you checked if the heads straight with a straight edge and feeler gauge?

Better do so, you wouldn't want to be bolting on a warped head.

[Stoney85]

Checked the head and it's all good, plus it was only machined a few thousand kms ago.

So it turns out I already had a 1.25mm restrictor in place, I just assumed it was stock, still haven't received the one I ordered anyway, my fault for not even measuring it previously, rookie error.

So with that knowledge, I cleaned everything up, and fitted the head, new Cometic MLS 87mm gasket and ARP studs torqued to 105ft/lb in three steps, I dry installed it as per manufacturers recommendations, found conflicting reports on that, but went with their way.

Fitted the rear head breather mod (aka rear head drain), as I had this setup already for the previous motor, swapped it from the JHH head that needs rebuilding.

Intake and 6 boost manifold is on, fitted the timing belt, and thats all good, sump etc is all sorted.

Tomorrow night is when I'll take it off the stand and fit the OS giken triple plate and gearbox, then fit it back to the car! Would be finished this weekend, but I'm a bit hesitant on that, good mates 30th this saturday, so thats sunday gone.

Appreciate your insight so far though, certainly gives me more confidence i'm doing it correctly.

[Stoney85]

Also, will decide on whether to fit the stock balancer or the Ross balancer, always have had problems with the Ross spitting p/s belts, never once with the stock

[djr81]

Dont put an old stock balancer on a new engine.

[Stoney85]

That was my thinking too, I guess i might have to either invest more money into the tensioner fix Ross released because they cant make a correct part to start with, or trial a few different belts out other than gates.

[doo doo]

A tip with the cometic head gasket- start the engine up without coolant in it and then start to put coolant in once started (or use straight distilled water?). I've seen new cometic head gaskets leaking coolant before start up- apparently the engine heat seals the gasket (only takes a few seconds, also why you install them dry) then you're right to add coolant. Would be interested to know if anyone else has experienced this.