Crank shaft machineing?

[skullkraxx]

How can you tell if it is necessary to have the crank shaft reground? How much should it cost? I have plastigauge but I have not used it yet. Any helpfull advice is greatly appreciated.
Thanks for the help [img]graemlins/finishflag.gif[/img]

[Bob]

Well, here's what I would do. Look at all the journals, if they all look nice, and the engine wasn't makeing any noise when I took it apart, they you are probably good. Take a piece of crocus cloth the width of the journal, wrap it around the journal. Take a piece of string and wrap it around the cloth a couple of times. Then roll the cloth around the journal with the string a few times to polish it. After doing this through the whole crank, drop it in the engine and plasigauge it. Your clearances will probably be on the wide side. That's OK. I think race motors aim for .002 to .0025" so if you come up with .0015 your fine, even leaning on .002.

[BillK]

sk,
If you are not familiar with engines, take the crankshaft to your machine shop and have them measure it for you. I hope Bob does not mind this comment but ... I have seen too many cankshaft ruined by the home mechanic using crocus cloth. I would not recommend it unless you are very familiar with engine repair. Plastigage will not tell the entire story on a crankshaft. It does not show out of round, or taper on the journals unless you are very familiar with what to look for. In our area crankshaft regrinding is running in the area of $140

Just my opinions,

[malc]

Go back to first principles. Start with a clean, well-lit inspection area. You want to CAREFULLY examine each and every one of the crank journals. You will soon recognise even by comparing adjacent journals which are good and which aren't. Look for cracks where the journals meet the webs. If there are any cracks then the crank needs work; likewise if one or more journals look like a ploughed field, get it done. Buy a cheap digital calliper and measure at least four places on each journal. When you put it back together, use the correct new parts - Mains and big-ends; rod bolts; the best gaskets you can afford; quality oil, oil and air filters; good but standard spark plugs; Best quality plug wires and points/condenser.
Best of luck, Malc