pcakes55 Posted January 29, 2010 Share Posted January 29, 2010 So, I'm not sure if this is normal, a performance mod to lighten the inertia of the counter weights (to make it rev faster?), or a SH*T job of balancing. Here are the pictures: There's no way this can be good..maybe (HOPEFULLY) I'm wrong. Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted January 29, 2010 Share Posted January 29, 2010 wow. Ill be watching this topic. Quote Link to comment Share on other sites More sharing options...
jc052685 Posted January 29, 2010 Share Posted January 29, 2010 This is more what you would be looking for. Also this... http://www.broadfootracing.com/Knife-edged_Crank_3.JPG Quote Link to comment Share on other sites More sharing options...
johnc Posted January 29, 2010 Share Posted January 29, 2010 The pic at the top is just a step in the machining process. That crank is not finished so there's nothing really to comment on. Quote Link to comment Share on other sites More sharing options...
pcakes55 Posted January 29, 2010 Author Share Posted January 29, 2010 This is how it looked when I pulled it out of my motor. Quote Link to comment Share on other sites More sharing options...
johnc Posted January 29, 2010 Share Posted January 29, 2010 Holy crap! Quote Link to comment Share on other sites More sharing options...
Evan Purple240zt Posted January 29, 2010 Share Posted January 29, 2010 John, what else needed to be done to finish that? Quote Link to comment Share on other sites More sharing options...
pcakes55 Posted January 29, 2010 Author Share Posted January 29, 2010 So you're saying the machine shop (whoever built it before I had it) just did not finish the balance job? Quote Link to comment Share on other sites More sharing options...
jc052685 Posted January 29, 2010 Share Posted January 29, 2010 The pic at the top is just a step in the machining process. That crank is not finished so there's nothing really to comment on. This is how it looked when I pulled it out of my motor. Holy crap! Haha! Sooooooo funny! Quote Link to comment Share on other sites More sharing options...
johnc Posted January 29, 2010 Share Posted January 29, 2010 (edited) I'm not a engine machinist by any means but, from the picture, I think they can at least deburr and polish the work they did - at a bare minimum. BRAAP would know much more about this then I. If they handed that crank to me my first words would be, "When will you be finished with it?" Edited January 29, 2010 by johnc Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted January 30, 2010 Administrators Share Posted January 30, 2010 (edited) John summed up what I see pretty well, …If they handed that crank to me my first words would be, "When will you be finished with it?" Whatever the previous shop did, they did NOT finish the job properly, that is without doubt! Is that a special crank, i.e. V07 stroker or? Looks like an L-6 crank that has been lightened with holes drilled into the counter weights and the counterweight cheeks roughly machined as well as the OD of the counterweights in an effort to reduce rotational mass. Turning down the OD of the counterweights could also be due to the use of a short con rod causing piston skirt-to-crank counterweight clearance issues. Being as the L-6 is neutrally balanced, it does not use bob weights. That makes lightening these cranks relatively straight forward. Just remove equal amounts off the opposite side as you lighten, then be sure to have it balanced. This particular crankshaft looks as though a novice or early amateur with access to a machine shop attempted the work. At that, even the novice/amateur engine builder knows better regarding deburring and would’ve most likely finished the job before handing it to the customer, (or the novice WAS the customer). Moving on. If this crank is intended to be used, have it magnafluxed first. If the crank mags good, then start deburring all the rough edges, (TONS of deburring work to be done based on those two pics alone). If the crank is just an L-28 crank, you might be money and time ahead to source a known good used crank and using that one as a mail box pole or end table lamp, etc. , (deburr it to make finger-friendly first). After the deburring, have the crank polished and balanced. Don’t bother deburring if you don’t plan on balancing it as the deburring will drastically affect that cranks balance! That’s my $.02 based on the two pics posted. Edited January 30, 2010 by BRAAP Quote Link to comment Share on other sites More sharing options...
NewZed Posted January 30, 2010 Share Posted January 30, 2010 How well did it run with that crank (assuming it did)? And what do the other engine components look like? Port work on the head, intake matching, etc. There must be some other goodies in there. Just curious... Quote Link to comment Share on other sites More sharing options...
pcakes55 Posted January 30, 2010 Author Share Posted January 30, 2010 Wow thats really unfortunate news lol. I never actually heard the motor run (i got a good deal on it, and he delivered it to me), but the guy said it ran great and his only reason for getting rid of it was he was doing a 350 swap; And everything else looks excellent (cyl walls, pistons, even the main/rod bearings have minimal wear). This was an N/A f54 for the record. The only other things I've noticed about the motor is that it's been bored .75mm over, and the crank is ground .25 under. Even though it's going to put me back $350 at the shop to have it the rotating assembly balanced, I was going to do it anyways. What can I use to deburr the crank anyways, just a file? Also, will the loss of weight affect the drivability? I intend on eventually tracking the car, but mostly just driving on the street until I'm done with school. This will sort of act on the same idea as a lightened flywheel, no? Quote Link to comment Share on other sites More sharing options...
pcakes55 Posted January 30, 2010 Author Share Posted January 30, 2010 Oh yeah, this is a normal l28 crank btw; Not a VO7, etc. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted January 30, 2010 Share Posted January 30, 2010 Get a good used crank and save some money. Post a crank wanted ad I suggest. Quote Link to comment Share on other sites More sharing options...
jeffer949 Posted January 30, 2010 Share Posted January 30, 2010 If you need a crank im sure i can work something out to send it to you when i send the rest of your stuff. Quote Link to comment Share on other sites More sharing options...
BluDestiny Posted February 2, 2010 Share Posted February 2, 2010 That thing looks like s***. Quote Link to comment Share on other sites More sharing options...
steve260z Posted February 4, 2010 Share Posted February 4, 2010 That is SWEET....... Quote Link to comment Share on other sites More sharing options...
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