Main Bearing Clearance Issue?

[AndrewS13]

I'm doing a full rebuild of my sr20det. My crank had very minimal scoring, so I took it to the machine shop with the rest of my block and paid to have the crank micro polished and measured. The machine shop told me the crank was all within spec (less than 5000 miles on crank). Since the crank was within spec, I bought standard clevite bearing. However, my clearances are giant on my main bearings. The plastigage doesn't even get smushed (0.08 mm+ of clearance. My guess is close to 0.1mm). How is this possible if my crank is within spec? Do I need to take it back to the machine shop and have my crank remeasured for oversize bearings? Should I just buy bigger plastigage and find out what my clearances currently are? This is only my 2nd turbo engine rebuild.

[thegr8one013]

If its all the journals then it could be that you bought the wrong bearings or the crank was previously cut before you had the motor.

Do you have the old bearing to compare thickness?

What is the part number of the bearings you bought?

[AndrewS13]

If its all the journals then it could be that you bought the wrong bearings or the crank was previously cut before you had the motor.

Do you have the old bearing to compare thickness?

What is the part number of the bearings you bought?

https://www.enjukuracing.com/products/clevite-rod-main-bearings-nissan-sr20det.html

Which is MS-2015A main journals:
https://www.amazon.com/Clevite-MS-2015A-Engine-Crankshaft-Bearing/dp/B013DK5KAS

I purchased these bearings. I do have old bearings, but I do not trust them to have been within spec. I purchased the motor on a fresh rebuild and the cylinders wereovaled and it was leaking like crazy. Bearings were roughed up.

Wouldnt the machine shop have let me know if the crank was previously grinded when they measured it? they said it was within spec.

[AndrewS13]

I just checked, and the old bearings are the exact same size (looks to even be the same brand).

Also, it is all of the journals.

[thegr8one013]

It could be possible that the machinist did not check your journal diameters.

Your only option is to buy a cheapo vernier scale and see what it reads. If it shows smaller than normally then take it back to the machinist so he can tell what soze bearings you'll need

[thegr8one013]

Actually i just noticed the part number u supplied is for sr20de. Ms2015p is for sr20det. They may be different journal diameters

[AndrewS13]

They're the same bearings.

The machinest definitely fucked me over. Looking at the oil holes you can tell they ground the journals. I paid them to measure the journals. They said they were within spec.

I have no clue what the machine shop was thinking, but I just ordered a new crank so I don't have have to deal with oversized bearings.

[TheRealSy90]

Now measure the journals and order the appropriate sized bearings, not a "one size fits all" kit.

[AndrewS13]

Now measure the journals and order the appropriate sized bearings, not a "one size fits all" kit.

Do you know where I can get 0.08 mm oversized bearings? I'm pretty sure I'd need to get the crank machined again to fit oversized bearings.

[TheRealSy90]

You shouldn't need oversized bearings. If you have a block and crank both with good journals, you use the markings on the crank and the markings on the block to determine which bearing sizes to run, according to the FSM.

[AndrewS13]

You shouldn't need oversized bearings. If you have a block and crank both with good journals, you use the markings on the crank and the markings on the block to determine which bearing sizes to run, according to the FSM.

I need oversized bearings. The crank journals are not good. They've been ground out of clearance. I checked and the correct OEM bearings based off of the crank and block numbers would still be much too small.

However, It is not ground down enough (or evenly enough) to run oversized race bearings. That crank is unuseable as is. I have a new crank on its way and I'll be trying to get my money back from the machine shop for the work they did on the crank.

[Kingtal0n]

Whats that, you found a rebuilt sr20 that was messed up by a machine shop, and thought that you would bring parts from it to a machine shop?
ah ha


The number one rule of rebuilding an engine (if you dont own a machine shop) is to do everything yourself, avoid the machine shop completely unless you can verify the work exactly

i would use an untouched oem crank with oem bearings... buy your own tools... you can follow fsm and come out ok.
But the block you start with needs to be a clean original engine thats not been touched, ever, by any machine shop

[AndrewS13]

Whats that, you found a rebuilt sr20 that was messed up by a machine shop, and thought that you would bring parts from it to a machine shop?
ah ha


The number one rule of rebuilding an engine (if you dont own a machine shop) is to do everything yourself, avoid the machine shop completely unless you can verify the work exactly

i would use an untouched oem crank with oem bearings... buy your own tools... you can follow fsm and come out ok.
But the block you start with needs to be a clean original engine thats not been touched, ever, by any machine shop

No worries I learned from my mistake. Untouched OEM crank is installed and clearances were perfect.

Now I need to figure out what to do with the crank that the machine shop fucked up. I should've just sent that crank as is. It only had one tiny scratch I could barely feel with my nail and only had 7500 miles on it.