Oversize Bearings? Plastigauge, First Rebuild Rb25

[zac320]

Hey guys I'm doing my first rebuild on a car engine. Done plenty on dirt bikes chainsaws ects.

Here's a run down I'm pretty much just giving my rb25 a freshen up while I replace a bent rod due to a hydrolock.

Reuse standard head (maybe new valve springs)

Arp headbolts

Reuse pistons with new OEM rings

Rb26 rods with arp bolts

Acl race series bearings mains and big ends(reuse rb25 piston pins on 26 rods?)

Now it's all pretty straight forward except bearings as I've never done them before. Is plastigauge good to use? Can I just use it to measure clearances? I don't own a micrometer and would rather get by without one for now. I just need to know how to measure clearances so I know what bearings to order.

BTW - Small country town no "engine builders" around, just a bunch of old blokes stuck in their ways.

Yes it would be easier to get a running 25 shortblock, cheapest I've seen is $700 in the city so add $300 for my travel expenses and we are at a $1000 which is what this freshen is probably gonna cost me! I know what engine I'd rather have.

Here's a quick list of prices off me head

Genuine Nissan gasket set $200

OEM rings $180

Bearings $250

Rb26 rods $75

Arp head studs and rod bolts $300

[KiwiRS4T]

Does your small town have a hire centre? It would be good to get a micrometer to measure wear on the bores and out of round to see whether you are wasting your time rebuilding or not.

I believe if you are going to replace the rod bolts (good idea) you need to rebore the big ends.

Nothing wrong with plastigauge in my view .....some younger compatriots get sniffy about it but I think ideally you measure and then check with plastigauge if you want.

[33GTRV]

Hi buddy, you are gonna need to get yourself some mic's before you do anything. The bores need to be checked for round and size, and if they are not within spec, its a rebore and new slugs or a wrecker engine. As for the arp bolts in the rods, the big ends will need to be rechecked for size when you fit them. I personally use plastiguage AND a mic when assembling to double check bearing clearances. Best of luck mate, its a little more involved than most people think

[zac320]

How much is a good mic? And is it hard measure clearances out of round? Ect

I wish someone had a good con 25 bottom end!!

Im from bairnsdale 3875!

[kitto]

0-25mm Micrometer should only be around $70 - $90 for a pretty good one. I bought a Starret 25-50mm unit a few weeks back for $99.

To check the bore's you really do need a proper bore gauge, and you don't want to go out and buy one of them unless you plan on rebuilding many engines in the future. Would be a costly tool i'm sure.

Really your cheapest option for sure is to buy a second hand engine as been said in many of your other posts.

Buy second hand engine, spend money putting new exhaust studs on it, water pump, timing belt kit etc and put it in.

Yes i understand you want to rebuild your engine, but if your bores are out then your going to have to bore it and get new pistons anyway. Then the snow ball begins....

[zac320]

I know but I can't find any bottom ends in good nic.

Answer this I had about 3 liters of water in my engine when I drowned it as it was siting there in the water. It sat for about a day and I replace oil/water lol. Bearings would be rooted yes? I'm

Considering just pulling the rods and putting the 26 ones I got for $75 in, plus might aswell throw new rings in it so there's $250 all up and then just my time.

[discopotato03]

Depending on the condition of the engine and what you want it for you could replace the bent rod provided its exactly the same centers length and replace the bearings with the same size the originals were . Being fresh they should work fine and obviously did from the factory . Really a glance at the crank journals and used bearings will tell you if its forked or not , low oil pressure could be another indicater of worn bearings .

I don't consider RBs "weak" from the factory and if you're not asking for much more than std performance fancy bolts and 26 rods won't do a lot for you .

If the engines worn out or damaged by water or the lock it needs a rebuild but if it wasn't and is ok the budget option is to fix whats bent and leave what isn't .

If this is for a Patrol you should be able to use an RB30 short though the conversion takes a bit of time and money .

A .

[zac320]

It is for a patrol mate. Was going the 30det route. But I've spoken to an engineer and he saidiota a bit of work with emmisions ect, he said if I go stock 25det, as in intake exhaust and turbo he will pass it. 2 conrods are bent as the engine won't fully turn over. Bores look fine except from a bit of rust on them, when I mine bit, it's under cover and it gets sprayed with crc frequently and the "rust" wipes off with my finger. When I say 26 rods it's just because I can get a set for $75.

Currently just the block is siting in car with every bolt but removed. I didn't have an engine crane till a couple of days ago. I guess I'll pull it and check the bearings, if there's not rust, (shouldn't be motors full of oil) I'll slap the new rods and rings in, car was running fine until the hydrolock. And bores haven't been marked from the lock

[33GTRV]

If it has hydrolocked that bad that its done 2 rods, throw it. Good chance the crank is bent, and in turn oil pump damage. Might not be what you want to hear, but its what id be doing.

[zac320]

Yeah your probably right mate, I was just about to pull it and strip it down then ahwell I'll do something else then haha