Polishing crank journals
12-04-2006, 11:07 AM
#1
Intermediate
Thread Starter
Polishing crank journals
Anybody have experience polishing crank journals?
The unthinkable finally happened, and I blew up a motor.
Luckily, a buddy's LT1 short block was available as a replacement. I'll be installing new rod and main bearings, and want advice regarding cleaning up the crankshaft journals.
Most look pretty good - no scoring or visible marks. Several of the old bearings have captured stuff, as they're designed to do, and on a couple crank journals you can feel a VERY SLIGHT ridge as you drag a fingernail across it.
The short block is upside down on a stand, so it's easy to work on, and I figured I'd replace the bearings without removing the crank. I've successfully "rolled out" a couple bearings, and will use the same technique for installing the new ones, cleaning up each journal while its bearing is out.
For cleaning up and polishing the crank journals, what's the recommended technique? I plan to lightly sand each journal by wrapping a strip of oiled 600-grid sandpaper, and making a couple of gentle passes.
Anybody have experience with this? Is 600 too coarse to for a "clean up" job? I assume oil is the best cutting fluid here. Thanks!
~~~~~~~~~~~
BTW, for anybody thinking about using LT4 springs and rockers in an LT1, my advise is DON'T. The motor lasted two seasons like this, but the LT4 retainers don't appear to be strong enough to handle anything but the lightweight valves used in the LT4. I'm the second person I know of that dropped a valve due to a failed LT4 retainer. It cracked around the periphery, allowing the entire retainer to pull down into the spring.
Second piece of advice is don't keep driving the car like this...
The unthinkable finally happened, and I blew up a motor.
Luckily, a buddy's LT1 short block was available as a replacement. I'll be installing new rod and main bearings, and want advice regarding cleaning up the crankshaft journals.Most look pretty good - no scoring or visible marks. Several of the old bearings have captured stuff, as they're designed to do, and on a couple crank journals you can feel a VERY SLIGHT ridge as you drag a fingernail across it.
The short block is upside down on a stand, so it's easy to work on, and I figured I'd replace the bearings without removing the crank. I've successfully "rolled out" a couple bearings, and will use the same technique for installing the new ones, cleaning up each journal while its bearing is out.
For cleaning up and polishing the crank journals, what's the recommended technique? I plan to lightly sand each journal by wrapping a strip of oiled 600-grid sandpaper, and making a couple of gentle passes.
Anybody have experience with this? Is 600 too coarse to for a "clean up" job? I assume oil is the best cutting fluid here. Thanks!
~~~~~~~~~~~
BTW, for anybody thinking about using LT4 springs and rockers in an LT1, my advise is DON'T. The motor lasted two seasons like this, but the LT4 retainers don't appear to be strong enough to handle anything but the lightweight valves used in the LT4. I'm the second person I know of that dropped a valve due to a failed LT4 retainer. It cracked around the periphery, allowing the entire retainer to pull down into the spring.
Second piece of advice is don't keep driving the car like this...
12-04-2006, 11:18 AM
#2
Race Director
Member Since: Sep 2000
Location: The Top of Utah
Posts: 17,298
Likes: 0
Received 23 Likes
on
22 Posts
Most of what you plan sounds about right, but I sure wouldn't do it in the block. Where do you think the metal sanded off and worse, the carborundum from the paper will go?
RACE ON!!!
RACE ON!!!
12-04-2006, 11:24 AM
#3
Intermediate
Thread Starter
Originally Posted by CFI-EFI
Most of what you plan sounds about right, but I sure wouldn't do it in the block. Where do you think the metal sanded off and worse, the carborundum from the paper will go?
Anybody have comments on how hard it is to remove the crank while leaving the pistons in place? I really don't feel like pulling them, but I guess this could happen as well. Obviously, put tubing around all the rod bolts...
12-04-2006, 12:41 PM
#4
Safety Car
Originally Posted by z07lt1
Anybody have experience polishing crank journals?
Most look pretty good - no scoring or visible marks. Several of the old bearings have captured stuff, as they're designed to do, and on a couple crank journals you can feel a VERY SLIGHT ridge as you drag a fingernail across it.
The short block is upside down on a stand, so it's easy to work on, and I figured I'd replace the bearings without removing the crank. I've successfully "rolled out" a couple bearings, and will use the same technique for installing the new ones, cleaning up each journal while its bearing is out.
BTW, for anybody thinking about using LT4 springs and rockers in an LT1, my advise is DON'T. The motor lasted two seasons like this, but the LT4 retainers don't appear to be strong enough to handle anything but the lightweight valves used in the LT4. I'm the second person I know of that dropped a valve due to a failed LT4 retainer. It cracked around the periphery, allowing the entire retainer to pull down into the spring.
Second piece of advice is don't keep driving the car like this...
Most look pretty good - no scoring or visible marks. Several of the old bearings have captured stuff, as they're designed to do, and on a couple crank journals you can feel a VERY SLIGHT ridge as you drag a fingernail across it.
The short block is upside down on a stand, so it's easy to work on, and I figured I'd replace the bearings without removing the crank. I've successfully "rolled out" a couple bearings, and will use the same technique for installing the new ones, cleaning up each journal while its bearing is out.
BTW, for anybody thinking about using LT4 springs and rockers in an LT1, my advise is DON'T. The motor lasted two seasons like this, but the LT4 retainers don't appear to be strong enough to handle anything but the lightweight valves used in the LT4. I'm the second person I know of that dropped a valve due to a failed LT4 retainer. It cracked around the periphery, allowing the entire retainer to pull down into the spring.
Second piece of advice is don't keep driving the car like this...
The answer is: you might /probably are ok to polish it, but it's possible you might have problems some day if you polish it. People disagree.
1. The polish camp:
If the score is so shallow that you can can't hang your finger nail it it, use emory paper. If you go too course you will ruin it, so it would be wise to start fine and see how it's going. My buddy did this in-car on a Buick and it worked fine for him for years. I think it was a fairly deep score too, deeper than mine. However, my crank had a score on just 1 journal that you could just barrrrrrely hang your fingernail in. I had the whole motor pulled out of the car ($1200 expense) and took the short block to a machine shop ($2000 expense because he screwed me over into a rebuild saying it needed pistons when in all likely hood it didn't--I changed oil Religiously--he wouldn't give me a straight number on the clearances, just that they were out) just for this 1 stupid little score. And during the rebuild process, I asked the machinist why he had not turned the crank as I had asked and he said "It doesn't need anything. I can take your money and turn it and that's more money for me." To which I responded "yes, turn it, more money for you".
2. I talked to at least one serious engine builder here that said a score like mine must be turned, if you take off more than 0.001", forget it, it will eat bearings for lunch. My mechanic when he saw the score said it would be "foolish" to continue. But this mechanic is not a machinist and does no rebuilding. My opinion of him now is that he is an idiot.
So that's it. IMHO, it is not worth all that expense for 1 stupid score, it does not make financial sense to do that. So in your case, just weigh in your mind how much it's going to be if you are wrong to pull the motor again--you have to pull the motor to get the crank out but you can put bearings in while the motor is in-car. In my case, it made a lot of sense to polish because the motor was still in-car and it was expensive for me to get it out plus there were not many shops that would turn the rebuild around in under a month.
For all my trouble with this, to top it off (it took 5 months to get this resolved precisely because that mechanic is an idiot), an SUV ran over the car with me in it on my first drive of the car to break the motor in after I drove it home. All that trouble for 90 mi.
Good luck.
Last edited by sothpaw2; 12-04-2006 at 12:56 PM.
12-04-2006, 01:11 PM
#5
Melting Slicks
Member Since: Feb 2006
Location: backwoods upstate ny
Posts: 2,753
Likes: 0
Received 12 Likes
on
10 Posts
crank MUST come out...you will get grit into the cross-drilled oil holes and only a blow-OFF will get it clean...dishsoap+ hot water+ rifle cleaning brush in the crossdrills, paint-brush on the externals...blow dry with compressed air and IMMEDIATELY wipe all externals and crossdrills with ''marvel mystery oil'' (or stand back and literally watch it turn brown with rust)
ez to pull the crank on the engine stand...MUST put protectors on the rod bolts (3/8'' fuel hose will work, i use bunches of ferd spark plug boots that are thin-walled/tapered/no loose ends)...to lay the crank back in WILL require at least one helper(two better) who has a clue.
400 grit wet/dry sandpaper is acceptable...seconds with 600 is superb...cut the sandpaper into strips the same width as the journal and wrap the journal (masking tape the end until you get experienced)and use a 4 foot long piece of clothesline once around the sandpaper/journal and ''shoeshine'' the clothesline to rotate the sandpaper on the journal (prolly take a few minutes to learn proper rope tension when newbie)...no cutting oil is required...change sandpaper as soon as it ''loads'' (typical to use up 6-8 sheets of 8-1/2x11 sandpeper per crank).....when you can see yourself in the crank you are good.
minor scores that do not polish out are acceptable.
all new cranks and ''turned'' cranks should be polished...most shops that turn cranks can polish for small $ but you can do a much better job by hand in this case
ez to pull the crank on the engine stand...MUST put protectors on the rod bolts (3/8'' fuel hose will work, i use bunches of ferd spark plug boots that are thin-walled/tapered/no loose ends)...to lay the crank back in WILL require at least one helper(two better) who has a clue.
400 grit wet/dry sandpaper is acceptable...seconds with 600 is superb...cut the sandpaper into strips the same width as the journal and wrap the journal (masking tape the end until you get experienced)and use a 4 foot long piece of clothesline once around the sandpaper/journal and ''shoeshine'' the clothesline to rotate the sandpaper on the journal (prolly take a few minutes to learn proper rope tension when newbie)...no cutting oil is required...change sandpaper as soon as it ''loads'' (typical to use up 6-8 sheets of 8-1/2x11 sandpeper per crank).....when you can see yourself in the crank you are good.
minor scores that do not polish out are acceptable.
all new cranks and ''turned'' cranks should be polished...most shops that turn cranks can polish for small $ but you can do a much better job by hand in this case
Last edited by redrose; 12-04-2006 at 01:26 PM.
12-04-2006, 02:53 PM
#7
Intermediate
Thread Starter
Originally Posted by redrose
crank MUST come out...you will get grit into the cross-drilled oil holes and only a blow-OFF will get it clean...dishsoap+ hot water+ rifle cleaning brush in the crossdrills, paint-brush on the externals...blow dry with compressed air and IMMEDIATELY wipe all externals and crossdrills with ''marvel mystery oil'' (or stand back and literally watch it turn brown with rust)
OK, so crank comes out. I've got a bunch of clear vinyl hose to use on the rod studs, and a willing, experienced helper available. I've installed cranks several times, but never with the pistons in.
The only thing that worried me was trying to get it back in with eight rods sticking all over the place.
I assume that one or two guys lowering the crank while someone else carefully guides the rods onto their journals would work. Maybe I can "sleeve" the rod journals with something like a wrap of cardboard tube to make sure they don't get banged up.When the crank is out, it should be easy to polish the journals - they are already pretty good, just very slight ridges that I'd like to level off before installing new bearings. And that makes me feel a lot better about positively keeping grit out of the motor.
12-04-2006, 04:10 PM
#8
Race Director
I have polished the crank journals under the car before with the engine in the car,
see this link
http://forums.corvetteforum.com/show...um_id=7&arch=1
see this link
http://forums.corvetteforum.com/show...um_id=7&arch=1
12-04-2006, 05:23 PM
#9
Large Impressive Member
Member Since: Jul 2003
Location: Good health is merely the slowest possible rate at which one can die
Posts: 65,789
Received 68 Likes
on
34 Posts
St. Jude Donor '04-'05-'06-'07
When you unhook the rods from the crank, push them and the pistons in as far as they'll go, and reinstalling it will be much easier. Also, no one's mentioned checking the crank for taper, out of round etc. This is obviously critical. Use emory cloth to polish it. Since it comes in a roll, it can be torn off in any workable length required. Plus, it's much more durable than even wet or dry when dealing with something as hard as a crank. You can wipe it on your pant leg occasionally and just keep going with it.
12-04-2006, 05:39 PM
#10
Safety Car
Member Since: May 1999
Location: Atlantis
Posts: 3,651
Likes: 0
Received 4 Likes
on
4 Posts
Cruise-In I Veteran
Here's a long story along the same lines as your crankshaft fixing post:
I pulled the pan on one of my racing engines 'back in the day' for a look-see.
It was a 327 4 bolt that I built on the kitchen table covered with a white sheet. True story. But my daddy had preached to me that 'cleanliness was next go Godliness' when it came to an engine.
It had been run a full season every weekend at the local circle track and I wanted to run it another season without rebuilding it.
What I saw sickened me.
ALL the main bearing journals were scored and looked pretty rough.
Had the car on a lift at the time at the shop of one of those 'old time' mechanics. He was an older friend of mine that helped me with my racing activities.
I told him, 'Lamar that thing won't make it two laps in that condition'.
My soulution involved pulling the engine and doing a complete rebuild.
Which meant I'd miss the season opening race. I thought the world would stop turning if I missed ANY weekend of racing but this was the season opener and I really wanted to be there.
Missing a race was something I just couldn't live with. After all they advertised on the radio that I'd be there so I thought I 'had' to be,LOL.
Man, the things you think when you're 25 years old.
Saturday was only three days away and I had no spare engine so pulling the engine meant I'd definitely miss the first race.
Lamar looked at it, rubbed his chin a little and said "Go ahead and put it back together with the new set of bearings".
I said, ok but it's not going to work.
Went ahead and 'rolled' the bearing halves out and rolled the new ones in along with the bearing cap half.
The engine ran the complete next racing season and won a LOT of races.
I pulled it down the next winter and the crank journals looked like brand new. It had 'burnished' and 'polished' out all the ridges and scratches. Looked like a brand new crank and the bearings looked ok.
I'm not saying yours will be ok but it very likely will be.
DO take the crank out of the block to clean and polish it.
600 is way, way, way to rough IMHO.
When I worked in the automotive machine shop again, 'back in the day' we polsihed with a long band of emory cloth turned by a motor and a couple of pulleys built onto the crank turning machine.
1000, 1500 and then 2000 will be better. Get it at Wally World if you REALLY want to spend a LOT of time polishing all those rod and main journals. I'd take mine to the 'cheen' shop instead.
Take the crank out so you can use a brush thru all the crank journals and make sure they are cleaned throughly.
At the same time you can clean the oil supply holes in the block.
There's really NO NEED NOT TO take the crank out of the block.
It's VERY easy to do so pull that sucker outta there.
It's better to have a shop polish it because the machine spins the crank and the entire journal surface is polished evenly.
They will mic. it for you too so you will know what your bearing clearances are going to be.
Get this clearance wrong and you'll have a very 'short lived' engine.
I did once. Engine ran GREAT but it had a vibration to it.
Drove it up on the hauler and told Lamar it was vibrating. That was a 68 Camaro body on a 57 Chevy frame so you older guys can figure out it was a LONG time ago. Built that car in the back yard 'under the trees'.
I pulled that one down to find it had spun ALL the rod bearings AND the mains.
I knew it was a little tight when I put it together but that was back before I had all the stuff to check things and 'do it right'.
IIRC it was the second racing engine I'd built all by myself.
Besides, TOO MUCH clearance was the thing you normally have using old 'stuff'.
That was another 327. End of the line for that one.
Here's another 'Moral To That Story':
If the crank doesn't spin FREELY after the mains are torqued down, there's too little clearance. It won't get better all by itself. It WILL overheat the bearings and cause a disaster.
It is not expensive to have the crank checked and polished.
Plan on replacing the timing chain and the rear main seal since the crank is out of the block.
If the crank is a little worn the machine shop can polish it evenly to where you can use .001 undersize bearings and bring it right back to GM specs. IIRC that's .003 or thereabouts. It's a little different for the rod vs. the main bearings.
Check the thrust bearing surface while it's out. Particularly if it's going into a stick shift car. If so knock the pilot bearing out of the rear of the crank and and knock a new one in there too.
If the old bearings look evenly worn (they WILL be worn more on the bottom bearing surface) then the crank will probably be ok. Maching shop can check it for taper and out of round and... a bonus, if you'll take them the block to clean it, they can put the crank in temporarily and check it for run out and straightness.
Oh, use a NEW oil pump or at MINIMUM take the old one apart and clean it up completely. A NEW pump is highly reccomended.
BTW......KEEP IT CLEAN!!!!!!!!!!!
LAST BTW: I NEVER ran a turned crank in any of my racing engines. Not saying they are inherently evil I just saw
too many good engines with turned cranks come apart. It would look like a roadside bomb went off under them.
I'd always save up and get a new crank or a good stock used one. TO this day I have an aversion to turned cranks although I turned them at the machine shop for folks to run in street cars and they worked ok for 'lower performance' applications.
Good luck and have fun with it.
Dadgum, I should write books.
I pulled the pan on one of my racing engines 'back in the day' for a look-see.
It was a 327 4 bolt that I built on the kitchen table covered with a white sheet. True story. But my daddy had preached to me that 'cleanliness was next go Godliness' when it came to an engine.
It had been run a full season every weekend at the local circle track and I wanted to run it another season without rebuilding it.
What I saw sickened me.
ALL the main bearing journals were scored and looked pretty rough.
Had the car on a lift at the time at the shop of one of those 'old time' mechanics. He was an older friend of mine that helped me with my racing activities.
I told him, 'Lamar that thing won't make it two laps in that condition'.
My soulution involved pulling the engine and doing a complete rebuild.
Which meant I'd miss the season opening race. I thought the world would stop turning if I missed ANY weekend of racing but this was the season opener and I really wanted to be there.
Missing a race was something I just couldn't live with. After all they advertised on the radio that I'd be there so I thought I 'had' to be,LOL.
Man, the things you think when you're 25 years old.
Saturday was only three days away and I had no spare engine so pulling the engine meant I'd definitely miss the first race.
Lamar looked at it, rubbed his chin a little and said "Go ahead and put it back together with the new set of bearings".
I said, ok but it's not going to work.
Went ahead and 'rolled' the bearing halves out and rolled the new ones in along with the bearing cap half.
The engine ran the complete next racing season and won a LOT of races.
I pulled it down the next winter and the crank journals looked like brand new. It had 'burnished' and 'polished' out all the ridges and scratches. Looked like a brand new crank and the bearings looked ok.
I'm not saying yours will be ok but it very likely will be.
DO take the crank out of the block to clean and polish it.
600 is way, way, way to rough IMHO.
When I worked in the automotive machine shop again, 'back in the day' we polsihed with a long band of emory cloth turned by a motor and a couple of pulleys built onto the crank turning machine.
1000, 1500 and then 2000 will be better. Get it at Wally World if you REALLY want to spend a LOT of time polishing all those rod and main journals. I'd take mine to the 'cheen' shop instead.
Take the crank out so you can use a brush thru all the crank journals and make sure they are cleaned throughly.
At the same time you can clean the oil supply holes in the block.
There's really NO NEED NOT TO take the crank out of the block.
It's VERY easy to do so pull that sucker outta there.
It's better to have a shop polish it because the machine spins the crank and the entire journal surface is polished evenly.
They will mic. it for you too so you will know what your bearing clearances are going to be.
Get this clearance wrong and you'll have a very 'short lived' engine.
I did once. Engine ran GREAT but it had a vibration to it.
Drove it up on the hauler and told Lamar it was vibrating. That was a 68 Camaro body on a 57 Chevy frame so you older guys can figure out it was a LONG time ago. Built that car in the back yard 'under the trees'.
I pulled that one down to find it had spun ALL the rod bearings AND the mains.
I knew it was a little tight when I put it together but that was back before I had all the stuff to check things and 'do it right'.
IIRC it was the second racing engine I'd built all by myself.
Besides, TOO MUCH clearance was the thing you normally have using old 'stuff'.
That was another 327. End of the line for that one.
Here's another 'Moral To That Story':
If the crank doesn't spin FREELY after the mains are torqued down, there's too little clearance. It won't get better all by itself. It WILL overheat the bearings and cause a disaster.
It is not expensive to have the crank checked and polished.
Plan on replacing the timing chain and the rear main seal since the crank is out of the block.
If the crank is a little worn the machine shop can polish it evenly to where you can use .001 undersize bearings and bring it right back to GM specs. IIRC that's .003 or thereabouts. It's a little different for the rod vs. the main bearings.
Check the thrust bearing surface while it's out. Particularly if it's going into a stick shift car. If so knock the pilot bearing out of the rear of the crank and and knock a new one in there too.
If the old bearings look evenly worn (they WILL be worn more on the bottom bearing surface) then the crank will probably be ok. Maching shop can check it for taper and out of round and... a bonus, if you'll take them the block to clean it, they can put the crank in temporarily and check it for run out and straightness.
Oh, use a NEW oil pump or at MINIMUM take the old one apart and clean it up completely. A NEW pump is highly reccomended.
BTW......KEEP IT CLEAN!!!!!!!!!!!
LAST BTW: I NEVER ran a turned crank in any of my racing engines. Not saying they are inherently evil I just saw
too many good engines with turned cranks come apart. It would look like a roadside bomb went off under them.
I'd always save up and get a new crank or a good stock used one. TO this day I have an aversion to turned cranks although I turned them at the machine shop for folks to run in street cars and they worked ok for 'lower performance' applications.
Good luck and have fun with it.
Dadgum, I should write books.
Last edited by VetNutJim; 12-04-2006 at 05:58 PM.
12-04-2006, 06:15 PM
#11
Melting Slicks
Member Since: Feb 2006
Location: backwoods upstate ny
Posts: 2,753
Likes: 0
Received 12 Likes
on
10 Posts
Quote: 600 is way, way, way to rough IMHO.
When I worked in the automotive machine shop again, 'back in the day' we polsihed with a long band of emory cloth turned by a motor and a couple of pulleys built onto the crank turning machine.
1000, 1500 and then 2000 will be better. Get it at Wally World if you REALLY want to spend a LOT of time polishing all those rod and main journals. I'd take mine to the 'cheen' shop instead.
[/b]
most of that post is good info, but ---
the ''bible'' for building high perf chevys is a book FROM chevy, titled (appropriately) as ''chevy power''.... written and verified for accuracy by a group of chevy engineers with countless hours of experience.....the ''bible'' recommends 400 grit and hand polishing..
i have seen several of the ''emery belt with electric motors'' polishing tools...great idea, if they would put on a new belt once in a while...a belt that is loaded with **** (yes, that is the technically correct term) will do nothing
When I worked in the automotive machine shop again, 'back in the day' we polsihed with a long band of emory cloth turned by a motor and a couple of pulleys built onto the crank turning machine.
1000, 1500 and then 2000 will be better. Get it at Wally World if you REALLY want to spend a LOT of time polishing all those rod and main journals. I'd take mine to the 'cheen' shop instead.
[/b]
most of that post is good info, but ---
the ''bible'' for building high perf chevys is a book FROM chevy, titled (appropriately) as ''chevy power''.... written and verified for accuracy by a group of chevy engineers with countless hours of experience.....the ''bible'' recommends 400 grit and hand polishing..
i have seen several of the ''emery belt with electric motors'' polishing tools...great idea, if they would put on a new belt once in a while...a belt that is loaded with **** (yes, that is the technically correct term) will do nothing
12-05-2006, 08:59 AM
#12
Intermediate
Thread Starter
Thanks to all the posters for the great advise! 
I always get way more than I pay for when I ask for tips.
I pulled the crank last night, so it's sitting on the bench waiting for cleanup. After checking carefully, it appears the rod journals are in excellent shape. A couple of the mains have VERY minor scratches, so I'm not going to do anything more than a really light sand/polish job.
The motor had 35K miles on it, probably about 1000 on the track, so it's really in pretty good shape. Very clean inside, and cylinder bores looked almost factory. Too smooth - one piston pushed down so easily it popped a ring out, so I'll have to use a ring compressor (or big hose clamp) to get that back in. The oil passages in the crank appear spotless. I really don't think it was in need of new bearings, but it just seemed silly to leave them if I had the motor open anyway. And if I didn't look, I would never know...
Sounds like popular opinion is that I should go a bit finer than the 600 paper I have now - I'll try to hunt up something better. Guess I could always take the crank to a shop for polishing, but half the fun is doing it yourself.
I assume a strip of paper the width of each journal is the way to go, and with long, slow strokes and light pressure (ooh - ahh!!!
). What's the concensus on wet (oiled) versus dry? I've always liked sanding/polishing with a lubricant to reduce loading and float away the material. Any reason not to?
TIA...
I always get way more than I pay for when I ask for tips.I pulled the crank last night, so it's sitting on the bench waiting for cleanup. After checking carefully, it appears the rod journals are in excellent shape. A couple of the mains have VERY minor scratches, so I'm not going to do anything more than a really light sand/polish job.
The motor had 35K miles on it, probably about 1000 on the track, so it's really in pretty good shape. Very clean inside, and cylinder bores looked almost factory. Too smooth - one piston pushed down so easily it popped a ring out, so I'll have to use a ring compressor (or big hose clamp) to get that back in. The oil passages in the crank appear spotless. I really don't think it was in need of new bearings, but it just seemed silly to leave them if I had the motor open anyway. And if I didn't look, I would never know...
Sounds like popular opinion is that I should go a bit finer than the 600 paper I have now - I'll try to hunt up something better. Guess I could always take the crank to a shop for polishing, but half the fun is doing it yourself.
I assume a strip of paper the width of each journal is the way to go, and with long, slow strokes and light pressure (ooh - ahh!!!
). What's the concensus on wet (oiled) versus dry? I've always liked sanding/polishing with a lubricant to reduce loading and float away the material. Any reason not to?TIA...
12-05-2006, 10:59 AM
#13
Safety Car
Originally Posted by VetNutJim
Here's a long story along the same lines as your crankshaft fixing post:
ALL the main bearing journals were scored and looked pretty rough.
Lamar looked at it, rubbed his chin a little and said "Go ahead and put it back together with the new set of bearings".
I said, ok but it's not going to work.
Went ahead and 'rolled' the bearing halves out and rolled the new ones in along with the bearing cap half.
The engine ran the complete next racing season and won a LOT of races.
I pulled it down the next winter and the crank journals looked like brand new. It had 'burnished' and 'polished' out all the ridges and scratches. Looked like a brand new crank and the bearings looked ok.
I'm not saying yours will be ok but it very likely will be.
DO take the crank out of the block to clean and polish it.
ALL the main bearing journals were scored and looked pretty rough.
Lamar looked at it, rubbed his chin a little and said "Go ahead and put it back together with the new set of bearings".
I said, ok but it's not going to work.
Went ahead and 'rolled' the bearing halves out and rolled the new ones in along with the bearing cap half.
The engine ran the complete next racing season and won a LOT of races.
I pulled it down the next winter and the crank journals looked like brand new. It had 'burnished' and 'polished' out all the ridges and scratches. Looked like a brand new crank and the bearings looked ok.
I'm not saying yours will be ok but it very likely will be.
DO take the crank out of the block to clean and polish it.
