KA24De engine rebuild, found something interesting. - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

bongnak · 09-17-2017, 02:27 PM

Hi all,
I'm in the process of building a ka24de and stumbled onto a weird situation and wondered if anyone else went through the same thing.

As we all know, when selecting bearings you can reference the markings on the crank and block to pick OEM graded bearings. At first this is what I did and have done in the past. This time I decided to do it the "accurate" way and bought a set of outside micrometers and a dial bore gauge.

So according to the fsm method and going off the stamped numbers on the block and crank I would have needed 1,1,0,0 graded rod bearings and 3,3,3,2,2 mains.

Ok cool, lets measure the journals and bores...
To my surprise after doing the math none of the markings are right.

The FSM has the specs for bearing thickness and after using that my measurements came out to grade 0 for both mains and rods, for all cylinders.

That's strange, I'm 99.9999% sure this is the first time this block has ever been taken apart since it left the factory.

Then this happened, I went to go measure the old bearings and sure enough they had part numbers on them and all of them were grade 0.

So now this makes me wonder about the damn markings on the block and crank.

Is this an isolated incident or have we been doing it all wrong?

Ps. if I were to go with the markings and use those bearings I would definitely spin bearings.

kyral · 09-21-2017, 04:37 PM

I bought a set of standard bearings and plastigauge for my budget rebuilds.
but from what ive noticed those markings seem to be an expensive waste of time buying individual bearings of different grades that are only a hair different in size

ive always disregarded them and used plastigauge or had my machine shop check them

from tearing apart KA's its pretty obvious that the utmost care was not taken at the factory so for the numbers to be wrong or off wouldn't surprise me

bongnak · 09-24-2017, 11:31 PM

Yeah I've done that in the past, but if you look at the required oil clearances in the fsm it's 0.0004 - 0.0014 inch for the rods.

The only plastigauge available (green) only measures to .0015 inch so if you do the plastigauge check and results in a 0.0015" clearance then your oil clearances are maybe at the max acceptable range.

09-17-2017, 02:27 PM	#1
bongnak Zilvia Junkie Join Date: Jan 2005 Location: So-Cal Age: 40 Posts: 337 Trader Rating: (3) Feedback Score: 3 reviews	KA24De engine rebuild, found something interesting. Hi all, I'm in the process of building a ka24de and stumbled onto a weird situation and wondered if anyone else went through the same thing. As we all know, when selecting bearings you can reference the markings on the crank and block to pick OEM graded bearings. At first this is what I did and have done in the past. This time I decided to do it the "accurate" way and bought a set of outside micrometers and a dial bore gauge. So according to the fsm method and going off the stamped numbers on the block and crank I would have needed 1,1,0,0 graded rod bearings and 3,3,3,2,2 mains. Ok cool, lets measure the journals and bores... To my surprise after doing the math none of the markings are right. The FSM has the specs for bearing thickness and after using that my measurements came out to grade 0 for both mains and rods, for all cylinders. That's strange, I'm 99.9999% sure this is the first time this block has ever been taken apart since it left the factory. Then this happened, I went to go measure the old bearings and sure enough they had part numbers on them and all of them were grade 0. So now this makes me wonder about the damn markings on the block and crank. Is this an isolated incident or have we been doing it all wrong? Ps. if I were to go with the markings and use those bearings I would definitely spin bearings. __________________ Zzzz Last edited by bongnak; 09-17-2017 at 02:34 PM.. Reason: add picture

09-21-2017, 04:37 PM	#2
kyral Zilvia Junkie Join Date: Nov 2012 Location: wisconsin Age: 32 Posts: 448 Trader Rating: (7) Rides Gallery: kyral Feedback Score: 7 reviews	I bought a set of standard bearings and plastigauge for my budget rebuilds. but from what ive noticed those markings seem to be an expensive waste of time buying individual bearings of different grades that are only a hair different in size ive always disregarded them and used plastigauge or had my machine shop check them from tearing apart KA's its pretty obvious that the utmost care was not taken at the factory so for the numbers to be wrong or off wouldn't surprise me __________________ The Game you lose haha

09-24-2017, 11:31 PM	#3
bongnak Zilvia Junkie Join Date: Jan 2005 Location: So-Cal Age: 40 Posts: 337 Trader Rating: (3) Feedback Score: 3 reviews	Yeah I've done that in the past, but if you look at the required oil clearances in the fsm it's 0.0004 - 0.0014 inch for the rods. The only plastigauge available (green) only measures to .0015 inch so if you do the plastigauge check and results in a 0.0015" clearance then your oil clearances are maybe at the max acceptable range. __________________ Zzzz