LS6427

iTrader: (2)

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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Busted Knuckles

As long as "they" wet mag and check it for dimension/straightness, run it.
Reasons not to run? Cracks would be number 1.

LS6427

iTrader: (2)

Any machine shop, or are there specialists for this process?

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Busted Knuckles

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.

ChucksZ06

iTrader: (9)

What is the history of the crank as it sits in your 427? Has it been run hard for a long time? Cranks are very stout pieces if they are taken care of.

LS6427

iTrader: (2)

124,000+ miles on my 427ci....100% street driven, never beed to a drag track. Only a street car having fun sometimes. Maybe once it week it sees ~175 mph out on an open highway, other that just daily driven with some fun.

As far as the engine is now...its running like it was new.

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ColeGTO

iTrader: (3)

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

LS6427

iTrader: (2)

Yea, it was installed in May 2002, its running great. I did have the valve seals redone in 2005, but thats it, they were just getting worn.

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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