Crankshaft journals?

[Bradical]

I am currently rebuilding an '85.5 2.5L for "fun".

Am I missing something? The workshop manual specifies the following crankshaft journal sizes...

Rod bearing journal 51.971mm (2.0461") to 51.990mm (2.0469")
Main bearing journal 69.971mm (2.7548") to 69.990mm (2.7555")

Are these the WEAR limits or the NEW sizes? Every measurement I have taken on my first rod journal appears to be 0.002-0.004" LARGER then those values (2.0489"-2.0507") so I am a bit confused.

Also, generally, is there an acceptable "out-of-round" limit? The two-thousands difference between my measurements could just be me not being careful to center the micrometer on the crank properly, but I am just curious how much of a width difference from woodruff to flywheel side on the journal is significant out-of-round wear.

I have just been playing around and haven't actually allotted time to blueprinting the crank just yet, so I'd like to put the measurements to good use.

[v2rocket_aka944]

i just measured the crankshaft i keep in my room ( ) and it was 2.040-2.047 but this crank has all 4 rod journals with nuked bearings.

my Haynes book says rod journal should be 2.047-2.048"

[Bradical]

The bearings on this engine were pristine, I am assuming that the higher measurement was an error? I think mic'ing the journals is more about oblong wear than anything, but maybe if the bearings were all good I don't really have any reason to check the crank? I am still going to blueprint the crank, if not just for kicks...

I am trying to make sense of it all, like how doing a plasti-gauge would make sense seeing as the rod nuts are one-time use. Do you use the old rod nuts for the gauge, or do you use the new ones and the untorque and retorque them? Info is limited on this stuff unless you apply the stuff you find on here from 911 engine builds...

[944 Ecology]

The rod nuts with the serrated flange are not one time use.

The rod nuts with the smooth flange should be thrown away and replaced with the ones with the serrated flange.

[Bradical]

The rod nuts with the serrated flange are not one time use.



The rod nuts with the smooth flange should be thrown away and replaced with the ones with the serrated flange.

Didnt know this, thanks!

I will be blueprinting the crank tonight, i'll post my findings with pictures for information.

[Bradical]

Alright! After taking great care getting everything centered perfectly my measurements make much more sense. Here are my measurements, two on either side of the journal and again at 90deg on both sides.

1985.5 2.5L, unknown mileage, bad oil cooler seal

Factory New Measurements - 2.0461"-2.0469"
Rod journal #1 - 2.0467", 2.0464", 2.0463", 2.0463"
Rod journal #2 - 2.0466", 2.0464", 2.0464", 2.0463"
Rod journal #3 - 2.0463", 2.0463", 2.0463", 2.0464"
Rod journal #4 - 2.0466", 2.0463", 2.0464", 2.0463"

Factory new measurements - 2.7548" - 2.7555"
Main journal #1 - 2.7550", 2.7551", 2.7551", 2.7551"
Main journal #2 - 2.7554", 2.7550", 2.7558", 2.7551"
Main journal #3 - 2.7551", 2.7555", 2.7552", 2.7554"
Main journal #4 - 2.7555", 2.7557", 2.7558", 2.7551"
Main journal #5 - 2.7554", 2.7551", 2.7551", 2.7551"

So my biggest out-of-round is main journal #4 at 0.0006". I double-checked it a few times. I'm not too concerned but I would love to know what the wear limit is if anyone can find it, I am assuming the rod journals are 0.0008" and the main journals are 0.0007" based on the information I have. Let it ride!

[Bradical]

Originally Posted by 944 Ecology

The rod nuts with the serrated flange are not one time use.

The rod nuts with the smooth flange should be thrown away and replaced with the ones with the serrated flange.

I found the page on the workshop manual that states your point, thanks again.