New Rod Bearings while apart - What is readily available at this time?

[fairlaniac]

My "replace rear main seal" project has turned into:
"Why is there coolant in my oil?" to "replacing the bearings".

Below are some links to pictures. I decided to replace my bearings if needed while the engine was out and disassembled this far. I see some wear on my rod bearings, one has the nickel coating worn to the copper, only the upper bearing of #2 is the nickel completely worn? All four rod journals are at 2.1995 (Scat stroker crank). The F/M bearings I have on hand are at 2.2025-2.2030 fitted in the rods. The currently worn bearings are Clevite bearings, STD Upper and .001 Bottom. I was getting .0025-.0027 clearance at assembly. I could get any lower with the bearings I had available at that time.

When I assembled this engine 3 years ago, it was the first time using a bore gauge. I may not have been as accurate as needed. I say this in case there is questions about prior dimensions.

I assume I should shop for some -.001 bearings and use one half or both if needed?

FYI - the main (accept #3 as it is not off yet) and the cam bearings look spotless. I see no need to change them.

Also, there appears to be rust behind the rear oil slinger on the crank? How can that happen?

Oh yeah, any tips on getting the #3 main bearing cap off? It's a stiff wiggle and doesn't seem to loosen any more? My shoulder hurts from trying to wiggle the #3 cap. Break time.

Pictures:
Upper bearing #2.
http://www.fairlanet.com/images/rb1.jpg

F/M bearings
http://www.fairlanet.com/images/rb2.jpg

Rust behind slinger.
http://www.fairlanet.com/images/rb3.jpg

#1-#4
http://www.fairlanet.com/images/rb4.jpg

Thanks,

[blykins]

Didn't you say you had coolant in the oil?  I wouldn't be surprised to see some rusty spots in some places. 

Your bearing clearances, if you measured correctly, are perfectly fine for a BBC rod journal.  I usually try to set them at .0022-.0025" in a street application.  An extra .0002" will not hurt anything. 

Did you make sure to put the "U" bearing in the rod and the "L" bearing in the cap?   Any evidence of detonation anywhere?  To me, it looks like not enough clearance, but just checking other things.

To get a stubborn cap off, put one bolt/stud in the hole in the cap, with a good bit of it sticking out the top, and smack the bolt/stud sideways with a dead blow. 

[fairlaniac]

Didn't you say you had coolant in the oil?  I wouldn't be surprised to see some rusty spots in some places. 

Your bearing clearances, if you measured correctly, are perfectly fine for a BBC rod journal.  I usually try to set them at .0022-.0025" in a street application.  An extra .0002" will not hurt anything. 

Did you make sure to put the "U" bearing in the rod and the "L" bearing in the cap?   Any evidence of detonation anywhere?  To me, it looks like not enough clearance, but just checking other things.

To get a stubborn cap off, put one bolt/stud in the hole in the cap, with a good bit of it sticking out the top, and smack the bolt/stud sideways with a dead blow.

Brent,
Yeah I had coolant in the oil. Just seemed odd to me to have it just on the back side in the corner of the slinger.

The "U" & "L" halves were in the proper locations.

I've noticed some bearings are to size and some not? If I use the F/M STD bearings I have on hand, I'll have at .003 and slightly over. It's a guessing game to me to decide which bearings to get and be more in the .0025" area.

[cjshaker]

Maybe it's just the picture, but that 1-4 shot, the lower left piston, upper bearing shell looks thinner right at the middle area, like maybe it's been flattened out from detonation. Have you measured bearing thickness in those areas to see if they're thinner? Just a no-cost check to give some piece of mind. I don't think that's the issue because detonation usually tears at the bearing surface, where yours look smooth, like it's a clearance or oil flow/viscosity issue. Especially because of the small area right in the middle where there is still babbit left, at least on several of them. That would typically be the worst area with detonation.

[blykins]

Didn't you say you had coolant in the oil?  I wouldn't be surprised to see some rusty spots in some places. 

Your bearing clearances, if you measured correctly, are perfectly fine for a BBC rod journal.  I usually try to set them at .0022-.0025" in a street application.  An extra .0002" will not hurt anything. 

Did you make sure to put the "U" bearing in the rod and the "L" bearing in the cap?   Any evidence of detonation anywhere?  To me, it looks like not enough clearance, but just checking other things.

To get a stubborn cap off, put one bolt/stud in the hole in the cap, with a good bit of it sticking out the top, and smack the bolt/stud sideways with a dead blow.

Brent,
Yeah I had coolant in the oil. Just seemed odd to me to have it just on the back side in the corner of the slinger.

The "U" & "L" halves were in the proper locations.

I've noticed some bearings are to size and some not? If I use the F/M STD bearings I have on hand, I'll have at .003 and slightly over. It's a guessing game to me to decide which bearings to get and be more in the .0025" area.

Shouldn't be a guessing game.  First thing I would do would be to take your crank, a rod, and a pair of bearings to your local machinist and let him verify your measurements.  If they agree, then it's an easy task of just buying the right bearings to get the clearances you want. 

If your clearances are verified, I would be looking at other causes though, because a rod bearing that looks like that with .0025" clearance clearly has other issues, whether it be coolant in the oil, detonation, trash in the oil, etc. 

Can you show the main bearings?

[fairlaniac]

Doug,
There is a worn spot on the #3 rod bearing, good eye. I don't have any pointed anvil micrometers to properly measure the bearing thickness at this time. I just have flat anvil micrometers. As for detonation? I don't ever recall any detonation episodes?

Brent,
Guessing referred to "guessing where I'll obtain some proper sized bearings". below are links to the main bearings, minus #3 as it is not off yet. #1 (darker) is a coated bearing that Blair provided when we were determining bearing sizes. I used the coated bearing to bump the clearance a "hair".

I'm fairly confident with my ability to measuring. I'm not a machinist but I do design equipment. That said, I'm humble enough to know when I'm doing something out of the norm. My comment about first time using a bore gauge was the first time I didn't use plastic gage. then again I hadn't assembled an engine since my 80's 5.0 days. So there is room for error. For insurance, my buddy, a machinist is stopping by tonight with his "tools" including his regular Starrett Bore Gauge and his Starrett/Accubore three point contact bore gauge. We'll see how it compares to my measurements.

Did you notice the etching on the pistons? 

http://www.fairlanet.com/images/mb1.jpg
http://www.fairlanet.com/images/mb2.jpg

Thank you for all of your help.

[Barry_R]

The clearance numbers you say you had should have been fine.  The one that's worn to copper looks "too tight" though.  The one with the spot of copper almost looks like loose clearance.  Water in coolant can do some weird stuff, but I would be checking everything really carefully as far as dimensions.  What's with the "pip marks" on the side of that one rod?  The .003" number would also work, and might help some things, but you really should not be showing the damage you have at .0025

[GerryP]

There may be a relationship between the "sludge" you found in your pan and the condition of the bearings.  I would collect that sludge and try to see what it is.  Maybe some abrasive material, casting material, or machining refuse that wasn't thoroughly cleaned out?  How do the mains look?  If it was an oiling issue, I would expect to see wear there too.  I have seen bearings spot wear from debris behind the bearing shell.  Also, some folks have put oil on the bearing's backside during assembly.  Everything needs to be clean and dry.

[Lowrider]

Your original post mentioned "rear main seal replacement". In your picture of rust behind the slinger, what happened to the angled "grooves" in the crank where the seal rides? Back in the 60's my old man told me they were there to help direct the oil back towards the engine. Could the missing grooves be contributing to the leak? Maybe someone can explain whether the grooves, missing or not, could explain any difference it might make.

[jayb]

The aftermarket cranks don't have those grooves.  That is unfortunate, because they do work to drive oil back into the engine when oil gets near the seal.  I think they were probably mandatory with the old rope style seals, and maybe the new rubber seals don't need them, but I know people who have put them on aftermarket cranks anyway.  One book I read said that the writer could never get the rear main to stop leaking until he had the crank machined with those grooves.  I'm not sure anyone has done a before and after test, but its something I've always been curious about...

[fairlaniac]

My buddy from work, a true machinist stopped over to verify/measure my rod journals and the set of new F/M bearing I have on hand.

Crank rod journals all 2.1995"
On hand new F/M bearings installed in rods range from 2.2025"-2.2027"

That is .0030-.0032 clearance. So if I had a -.001 half bearing to match. Would that be the best way to get in range? If so, where to get some matching F/M bearings at -.001? If not the preferred way, which bearing set to get that will be within range?

Had the crank been a true 2.200" I'd probably be fine. This is the journal diameter from new when I installed the crank so nothing had changed in the 500-ish miles. Not that it should.

Thanks,

[Jb427]

Could get your bearings calico coated. Coating thickness is around 0.00025 to 0.00030 Brent or Barry may know if that could be an option for you

[blykins]

My buddy from work, a true machinist stopped over to verify/measure my rod journals and the set of new F/M bearing I have on hand.

Crank rod journals all 2.1995"
On hand new F/M bearings installed in rods range from 2.2025"-2.2027"

That is .0030-.0032 clearance. So if I had a -.001 half bearing to match. Would that be the best way to get in range? If so, where to get some matching F/M bearings at -.001? If not the preferred way, which bearing set to get that will be within range?

Had the crank been a true 2.200" I'd probably be fine. This is the journal diameter from new when I installed the crank so nothing had changed in the 500-ish miles. Not that it should.

Thanks,

Ok, a couple of notes here:

1.  That is typically not how we measure bearing clearances.   The journal of the crank is measured with a micrometer, then a bore gauge is set to that micrometer.  The rod is torqued and then you use the bore gauge inside the rod to get the clearance.  I never measure the ID of the big end of the rod as doing so could introduce some error, unless you have a ring fixture or something like that.   You can check out this video that I made last week when measuring a Cleveland crankshaft:  https://www.youtube.com/watch?v=0a2Jre3Z3O4

2.  Just like pistons do not measure the exact bore size, crank journals do not measure their size either.  The journal diameter (2.1995") is what you normally see.  The main journals will not measure a dead on 2.750" either, they will be something like 2.7488 or 2.7491. 

3.  If....your measurements are correct, then yes, you would just match (assuming your rod bearings are both standard) a standard rod bearing with a .001" rod bearing and it would cut your clearance by about a half thou.  You should be using 8-7200CH rod bearings.  You would need some 8-7200CH1. 

[fairlaniac]

My buddy from work, a true machinist stopped over to verify/measure my rod journals and the set of new F/M bearing I have on hand.

Crank rod journals all 2.1995"
On hand new F/M bearings installed in rods range from 2.2025"-2.2027"

That is .0030-.0032 clearance. So if I had a -.001 half bearing to match. Would that be the best way to get in range? If so, where to get some matching F/M bearings at -.001? If not the preferred way, which bearing set to get that will be within range?

Had the crank been a true 2.200" I'd probably be fine. This is the journal diameter from new when I installed the crank so nothing had changed in the 500-ish miles. Not that it should.



Thanks,

Ok, a couple of notes here:

1.  That is typically not how we measure bearing clearances.   The journal of the crank is measured with a micrometer, then a bore gauge is set to that micrometer.  The rod is torqued and then you use the bore gauge inside the rod to get the clearance.  I never measure the ID of the big end of the rod as doing so could introduce some error, unless you have a ring fixture or something like that.   You can check out this video that I made last week when measuring a Cleveland crankshaft:  https://www.youtube.com/watch?v=0a2Jre3Z3O4

2.  Just like pistons do not measure the exact bore size, crank journals do not measure their size either.  The journal diameter (2.1995") is what you normally see.  The main journals will not measure a dead on 2.750" either, they will be something like 2.7488 or 2.7491. 

3.  If....your measurements are correct, then yes, you would just match (assuming your rod bearings are both standard) a standard rod bearing with a .001" rod bearing and it would cut your clearance by about a half thou.  You should be using 8-7200CH rod bearings.  You would need some 8-7200CH1.

Brent,
Thanks for the reply. I'm not sure what I may have typed that misled you but your measuring procedure is exactly how I measured journal diameter and bearing I.D.'s? I guess that is why I became and engineer and not a teacher ;-)

My "range" may not have been the best way to convey the "range" of measurements from each rod. Nice video. BTW, I hope you are feeling better.

Thanks!

[blykins]

Thank you.

Can you explain how you got 2.2025-2.2027?