discovered a knick on the crank, how bad is it?
11-30-2012, 01:06 AM
#1
discovered a knick on the crank, how bad is it? I'm in the process of rebuilding my bottom end and was inspecting the crank this evening, when I came across this knick on one of the main journals:
definitely can feel it with my finger, and i'd estimate that it'd require more cleanup than what's allowable for minimum journal diameter (with stock bearings at least). The journal mic'd out to the upper range of the spec, giving me about 0.0007-0.0008" I could grind down, but I think it's going to take more than that.
How bad is this damage and what would you do to fix it?
definitely can feel it with my finger, and i'd estimate that it'd require more cleanup than what's allowable for minimum journal diameter (with stock bearings at least). The journal mic'd out to the upper range of the spec, giving me about 0.0007-0.0008" I could grind down, but I think it's going to take more than that.
How bad is this damage and what would you do to fix it?
11-30-2012, 02:16 AM
#2
More than likely, that is poroisty (sp?) In the casting. I found something similar on a lobe on my stock cam. Probably fine for stock off the line, but any kind of performance build, I would have it ground or find a new crank.
If you decide to go with a different crank, pm me. I have a nice 6.0 crank.
If you decide to go with a different crank, pm me. I have a nice 6.0 crank.
11-30-2012, 04:45 AM
#5
I personally wouldn't worry about it if the journal polishes up within specs. If the imperfections was out at the edge of the journal I would be concerned because it would act as a passageway for oil to escape the clearance between the bearing and journal. Being that it's centered up on the journal I wouldn't be concerned.
11-30-2012, 07:24 AM
#7
How much could I expect this machine work to cost? Would I be better off trying to find a used crank? Or....I could just say to hell with it and build a stroker motor haha.
I'd be inclined to say the same - but I'd estimate that this thing is on the order of 0.010-0.015" deep, and from my measurements I've only got about 0.0008" (0.0004" on the radius) I could polish it until I'm at the service limit.
I see you're in PA also - do you happen to know of any machine shops that do reputable work? Everything around me is really hit or miss. I'm going to need to get my rods resized also, putting in ARP's.
I personally wouldn't worry about it if the journal polishes up within specs. If the imperfections was out at the edge of the journal I would be concerned because it would act as a passageway for oil to escape the clearance between the bearing and journal. Being that it's centered up on the journal I wouldn't be concerned.
I see you're in PA also - do you happen to know of any machine shops that do reputable work? Everything around me is really hit or miss. I'm going to need to get my rods resized also, putting in ARP's.
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11-30-2012, 10:45 AM
#10
I live in the Uniontown area. A good friend of mine has an engine machining facility. He does everything from flowing heads to balancing rotating assemblies. He is one of the best but doesn't really advertise his business to the public. He is a former drag racer who did his own engine's and some other racing team's engines on the side. I can PM you his number if you're willing to drive out here. As far as your crank goes it would cost about 200 bucks to have it reground. I couldn't tell you from pics how much it would have to be ground, obviously. It definetly needs reground to remove that blemish. You will ultimately have to decide what route you want to go. I can tell you now I'd forget the above suggestion about welding and regrinding the crank. That process is for high dollar cranks that you don't just pitch. A stock ls1 crank would be one to just pitch if it needs that kind of work.
11-30-2012, 12:31 PM
#11
I live in the Uniontown area. A good friend of mine has an engine machining facility. He does everything from flowing heads to balancing rotating assemblies. He is one of the best but doesn't really advertise his business to the public. He is a former drag racer who did his own engine's and some other racing team's engines on the side. I can PM you his number if you're willing to drive out here. As far as your crank goes it would cost about 200 bucks to have it reground. I couldn't tell you from pics how much it would have to be ground, obviously. It definetly needs reground to remove that blemish. You will ultimately have to decide what route you want to go. I can tell you now I'd forget the above suggestion about welding and regrinding the crank. That process is for high dollar cranks that you don't just pitch. A stock ls1 crank would be one to just pitch if it needs that kind of work.
So I'm not too keen on just throwing this crank in as is and seeing what happens, if I'm going to go to the trouble of rebuilding this thing I want it to be right. If I want to use this one, I'm basically looking at a regrind/polish for all journals to an undersize and using undersized (thicker) bearings? Are there any implications of running a setup like this that I may not be aware of - is the function/stiffness of the support compromised in any way using a thicker bearing? (Might be a bit out there, but just thinking about dimensional stability of the oil clearances)
Last edited by ckpitt55; 11-30-2012 at 12:56 PM.
