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scuffed crank journals

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Old 10-10-2002 | 11:20 AM
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Car: 1991 Corvette Coupe
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Transmission: 700R4/4L60 same trans different name
scuffed crank journals

what causes scuffed crank journals?

does the crank have to be turned to cure it?

please shed some light on this topic for me
Old 10-10-2002 | 12:33 PM
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His exact words are:

"You may want to get another crankshaft. The one in there has a little scuff."

I asked it it had already been undersized, or if emory cloth would polish it up:

"You can turn the crank but emory may do the trick. It really isn't bad but I want to be up front with everything. "

About the rest of the engine, the cam has less than 100 miles on it, I can remove it in front of him, and he'll back it up. No ridge or scratches in the bores, as the pictures you've seen Glenn back up...m He says this about the rest of the motor:

"Miles less than 4000. I installed it about 3 years ago and one season I didn't drive it at all due to got married, bought a house and so forth. It has never seen track and was completely babied when I drove it. I only did one burnout in it and that was too see if I could light up my 295/50/16 BFG's. Never over spun."
Old 10-10-2002 | 12:34 PM
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picture showing journals #1:
Attached Thumbnails scuffed crank journals-dsc00026.jpg  
Old 10-10-2002 | 12:35 PM
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#2
Attached Thumbnails scuffed crank journals-dsc00027.jpg  
Old 10-10-2002 | 02:32 PM
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Car: 1991 Corvette Coupe
Engine: L98
Transmission: 700R4/4L60 same trans different name
i'm thinking that the oil clearances were not proper, thus scuffs appeared

mite want to try to get the guy to knock some $$$ for a new crankshaft
Old 10-10-2002 | 03:17 PM
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I doubt I'll need a new one... I've worked cranks before that had bronze from the bearing scuffed into the journals, a little emory cleaned it up, and the engine ran fine with no knocks... granted it was a lawnmower engine, but it definatly had more abuse than this engine did.
Old 10-10-2002 | 06:29 PM
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bump
Old 10-10-2002 | 07:37 PM
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i think the pics are of the pins, the journals are on the mains. i might be wrong but the old guy that taught me a few things about engines explained it that way. i can't see or tell anything from your pics. the dark spots may be from old oil build up and heat. if the measure within spec they should be ok. i'd never put emory on a crank, you want a very fine finish. i put my cranks in my lathe to hold them and use crocus to polish them. few times i've used 1200 and 1500 wet/dry
Old 10-10-2002 | 07:52 PM
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The spots are oil holes...

And yeah... a crocus stone will work too.. usually used on a notch that will catch your finger nail...

on the lawnmower journal, we cleaned off the bearing material with emory, and then switched to finer stuff to polish it up... it ran fine regurdless.
Old 10-10-2002 | 07:57 PM
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i woulda just gotten another lawn mower
Old 10-10-2002 | 08:05 PM
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The new lawnmowers don't compare to those middle-70's snapper mowers man (coming from an ex-landscaper)... I needed an engine to work on for my mech class, and picked that one off the side of the road...
Old 10-10-2002 | 08:24 PM
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Car: 1991 Corvette Coupe
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Transmission: 700R4/4L60 same trans different name
Originally posted by ede
i think the pics are of the pins, the journals are on the mains. i might be wrong but the old guy that taught me a few things about engines explained it that way.

ummmm rod journals and main journal thats what i've always heard
Old 10-10-2002 | 08:27 PM
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Car: 1991 Corvette Coupe
Engine: L98
Transmission: 700R4/4L60 same trans different name
erik- get the engine home and then we'll worry about whats wrong

we'll buy some plasti-gauge and a micrometer to see whats wrong and what caused the problem

we'll check with the mike to see if the journals are in spec like ede said

when i see the snap-on guy tommorow, i'll find out how much he wants for a micrometer...........2-3inch

Old 10-11-2002 | 05:52 AM
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i meant the other dark spots, not the oil holes damn you think i ain't ever saw a crank before? as much as i like and use snap on tools i wouldn't buy a mike form them. find soemoen that sells starrett, cost you about 100 or little over. funny thing is i can buy starrett and lot of other makers stuff from my industrial snap on dealer but not off my personal dealer, and i can get 15 to 25 per cent off the catalog prices from the industrial rep.
Old 10-11-2002 | 10:15 AM
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Damn, 100 bucks for a micrometer? Just get some plastigauge... alot cheaper...

I just spoke to the guy once again... the engine had about 3900 miles on it when he pulled a 268/268 454/454 cam to put in the 2050 cam... he said it ran great with that cam, and thats when he found it had enough grunt to spin the 295 BFG's... Put another 100 miles on it, and pulled the engine to build a 383, but decided on a 406 instead...

And ede, didn't mean to offend, I know you know your stuff, but I don't see any other dark spots?
Old 10-11-2002 | 01:44 PM
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plasti gage is just about worthless, i'll stick with precision measuering tools
Old 10-12-2002 | 05:40 AM
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Car: 1991 Corvette Coupe
Engine: L98
Transmission: 700R4/4L60 same trans different name
erik- i talked to another mechanic at work today

he said crocus cloth should work on the crank great

just buy the damn engine already lol

anyway, instead of the micrometer, i bought a valve spring compressor off the snap-on guy instead

so, i'm going to go ahead and pull off one of those valves and make sure the guide is definetly ok

from what i can see, the guides were unharmed, but i'll just make sure anyway

i'm still trying to figure out why the hell 3 exhaust valves were bent


oh erik- @ about 10:00 am tommorow, i have to go pickup my sisters new car, i think you'd said you'd be here in the afternoon anyway

well, if not, come in the afternoon anytime you like after say 12:00

then you can see your mighty vortec heads!
Old 10-12-2002 | 05:42 AM
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Car: 1991 Corvette Coupe
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Originally posted by ede
plasti gage is just about worthless
hey, we're beginners

seriously though, thanx for all your help, ede
Old 10-12-2002 | 05:55 AM
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i know a lot of people use it and never have problems. the thing is it isn't very exact and it depends on you eyeballing it and comparring it to the scale. the one thing about plasti gage i do like is for a quick check just to make sure the shop never turned a crank too much or messed up measuering a crank, or the wrong bearings got in the wrong boxes or mislabeled. now that i have my own mikes and bore gages i have no use for plasti gage at all. i know we all started out not owning any tools or equipment but for around 500 dollars you can have most if not all the precession tools you'd need for an engine and if you buy your tools from off shore they can be had cheaper, but i believe starrett is the only way to go for precession tools.
Old 10-12-2002 | 03:23 PM
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Awesome Glenn, yes I'll be there in the afternoon... probably much later than noon... if you need to get in touch with me, after i reply to this post, I'll PM you my cell phone number, I can be reached there anytime.

I was diagnosed with pneumonia this morning. I don't remember if I mentioned to you or not, but I've been having chest pains for about a week and a half now, and just recently I've started coughing... I went to the doctor and jsut chest x-rays. As long as the x-rays come back ok, the doc thinks it's pneumonia. It's not bad at all, low grade fever, treatable with antibiotics.

Anyway since I had to go to the doctor this morning, I didn't get to pick up my old hood today. I'll probably do that tomorrow, and leave sometime after that.

I can't wait to see these heads. If you want, I'll take one of those 350 heads with me as well, so I can start working on those for you.

And I just got another responce back from the man with the 350. it looks like he may knock a fe bucks off the price for me, don't know yet. He mentined in the beginning of our conversations that he'd knock some $$ off for my travels, I just called him on it, so we'll see what he says. He said he had the crank checked out with some people, and they all said it wasn't bad. He said it's pretty mcuh up in the air weither I run it as is, or clean it up and put new bearings on it. He said it always held oil pressure for him, a solid 10 PSI for every 1000 RPM. And did I mention, the motor comes with a Melling oil pump? HV-55 I believe he said the P/N was...

I also spoke with my father about getting the engine home, right now the tenative dates are the 2nd and 3rd of November.

:rockon:
Old 10-12-2002 | 07:12 PM
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Car: 1991 Corvette Coupe
Engine: L98
Transmission: 700R4/4L60 same trans different name
ABOUT THAT VALVE SPRING COMPRESSOR

it does a great job of compressing springs with valves that are not bent

but because the bent valves caused those 3 springs to compress already, by nature of my VS compressor's design, i CAN NOT get those ****ING springs off

i tried for about 1/2 hour as soon as i got home from work today

oh yeah, i talked with another mechanic at work today, he said on a minor scuff, crocus cloth should work fine

and at work, they moved me to the alignment rack
seems we got another A-tech, and since i'm only a C-tech, he got my lift, so now i have to work on the rack, (but not do front ends, cuz the machine is broken)
Old 10-12-2002 | 07:14 PM
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1991tealRSt-topGuy's Avatar
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Car: 1991 Corvette Coupe
Engine: L98
Transmission: 700R4/4L60 same trans different name
oh yeah, erik, my real name is not glenn, i am keeping the heads, i am currently in brazil dealing with a druglord

j/k

heads are here waiting
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