re-use a crank or get a new one.....
re-use a crank or get a new one..... I have a 4.125 Cola crank. If I send it out to get checked and reworked (whatever it is they do) and it comes back perfectly fine, should I reuse it for a new engine build? Or get a new crank?
Whats the reason you wouldn't use a "used" crank? Its in my 427ci right now and everything is fine.
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Whats the reason you wouldn't use a "used" crank? Its in my 427ci right now and everything is fine.
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TECH Apprentice
Joined: Oct 2007
Posts: 302
Likes: 20
It'll have to be a decent performance shop, the wet mag setup isn't cheap. A dry powder magnaflux system doesn't work well on cranks, rods, etc., so that's why wet mag is the preferred system. It basically uses a liquid dye that glows under ultraviolet light.
As far as the engine is now...its running like it was new.
.
That's an *** load of miles on a performance build. I'm amazed your valve guides and seals haven't given up yet.
As far as the crank goes, have a reputable crankshaft machine shop check it out. There is some worry with fatigue life of a crank, but it really isn't tracked or documented well regarding the useable service life. Basically, if it isn't cracked and it's still straight, run it 'till it tells you otherwise.
Here's the proper process for checking a crankshaft:
Stress relieve
Mag. inspect
Check rod and main journal size
Check stroke index
Index grind rod journals (if required)
Grind main journals (if required)
Re-check stroke index
Polish all journals
Chamfer oil holes
Stroke Index - make sure the stroke is the same for all throws
Rod Journal Size - If they are a lot smaller you'll need a thicker bearing and probably a polish. If the journals are more than .002" smaller I would consider having the crank re-nitrided to maintain it's wear and strength charastics.
Magnetic Particle Inspection - Do a complete and thorough Magnetic Particle Insp., not just a Flourescent Penetrant Inspection. Magnetic Particle Inspection will pickup internal cracks and Flourescent Penetrant Inspection will only pickup surface cracks.
Cole
As far as the crank goes, have a reputable crankshaft machine shop check it out. There is some worry with fatigue life of a crank, but it really isn't tracked or documented well regarding the useable service life. Basically, if it isn't cracked and it's still straight, run it 'till it tells you otherwise.
Here's the proper process for checking a crankshaft:
Stress relieve
Mag. inspect
Check rod and main journal size
Check stroke index
Index grind rod journals (if required)
Grind main journals (if required)
Re-check stroke index
Polish all journals
Chamfer oil holes
Stroke Index - make sure the stroke is the same for all throws
Rod Journal Size - If they are a lot smaller you'll need a thicker bearing and probably a polish. If the journals are more than .002" smaller I would consider having the crank re-nitrided to maintain it's wear and strength charastics.
Magnetic Particle Inspection - Do a complete and thorough Magnetic Particle Insp., not just a Flourescent Penetrant Inspection. Magnetic Particle Inspection will pickup internal cracks and Flourescent Penetrant Inspection will only pickup surface cracks.
Cole
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That's an *** load of miles on a performance build. I'm amazed your valve guides and seals haven't given up yet.
As far as the crank goes, have a reputable crankshaft machine shop check it out. There is some worry with fatigue life of a crank, but it really isn't tracked or documented well regarding the useable service life. Basically, if it isn't cracked and it's still straight, run it 'till it tells you otherwise.
Here's the proper process for checking a crankshaft:
Stress relieve
Mag. inspect
Check rod and main journal size
Check stroke index
Index grind rod journals (if required)
Grind main journals (if required)
Re-check stroke index
Polish all journals
Chamfer oil holes
Stroke Index - make sure the stroke is the same for all throws
Rod Journal Size - If they are a lot smaller you'll need a thicker bearing and probably a polish. If the journals are more than .002" smaller I would consider having the crank re-nitrided to maintain it's wear and strength charastics.
Magnetic Particle Inspection - Do a complete and thorough Magnetic Particle Insp., not just a Flourescent Penetrant Inspection. Magnetic Particle Inspection will pickup internal cracks and Flourescent Penetrant Inspection will only pickup surface cracks.
Cole
As far as the crank goes, have a reputable crankshaft machine shop check it out. There is some worry with fatigue life of a crank, but it really isn't tracked or documented well regarding the useable service life. Basically, if it isn't cracked and it's still straight, run it 'till it tells you otherwise.
Here's the proper process for checking a crankshaft:
Stress relieve
Mag. inspect
Check rod and main journal size
Check stroke index
Index grind rod journals (if required)
Grind main journals (if required)
Re-check stroke index
Polish all journals
Chamfer oil holes
Stroke Index - make sure the stroke is the same for all throws
Rod Journal Size - If they are a lot smaller you'll need a thicker bearing and probably a polish. If the journals are more than .002" smaller I would consider having the crank re-nitrided to maintain it's wear and strength charastics.
Magnetic Particle Inspection - Do a complete and thorough Magnetic Particle Insp., not just a Flourescent Penetrant Inspection. Magnetic Particle Inspection will pickup internal cracks and Flourescent Penetrant Inspection will only pickup surface cracks.
Cole
So, how much does all that stuff cost and who would you recommened I send it to to get checked?
Thanks.
.
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