Here goes: I am building a standard bore d16a6 with 4.3cc dome SRPs, Eagle rods, the crank I am using is from the block I am using. Before I sent the block and crank to the machine shop I measured the crank for straightness and got questionable results--I didn't really trust these results because the mag. base dial indicator was very shaky--so I had my machinist measure the crank for straightness--he said its "fine" but he didn't give me an actual number for runout. I size up the bearings using OEM honda bearings and got around 0.0015"-0.0016" (estimation with plastigauge) I start assembling the bottom end with some lube--btw the main caps and girdle belong to this block and are not mixed up--the block never had an align bore/hone done to it. After I tighten everything down I turn the crank to see what the breakaway is--I can turn it easily with one hand but there seems to be a very slight "tight" spot in a certain location. Now, when I let is sit for 2-3 minutes in that "tight" spot it takes much more force to get moving again--once its moving again its no problem and will spin easily--when I let it sit with the crank in another part of its revolution its fine--its only when I let it sit in this particular postion that it sort of freezes up and takes some effort to breakaway--now even though I can still turn the crank it still doesn't seem right to me. So today I meausured the crank (again) for runout/straightness-I got numbers of 0.003" in the center #3, 0.002" on #2 and #4, and roughly 0 on 1 and 5. the Honda spec is a max of 0.002"--I used the same shaky setup to measure the crank but I was very deliberate this time. I think the crank is bent--if it was a bearing clearance issue like a main that was too tight I feel that the tightness would be all around not just in one spot--am I right? Also, my machinist is either lying to me and didn't measure, doesn't care or doesn't know what he is doing. I bought alot of bearings on his word that the crank was straight--so now I am looking for another crank. Everything is pointing to the crank being bent, but is it possible its the block that is at fault? In other words, would an align bore cure this? Or is it so minor that I can get by using larger main bearings? I don't want to do that as the bearings speced out great. I have wasted almost a month with this guy (machinist) and it just goes to show you you have got to double check everything they say. I just want to know what the best course is at this point.

 

Well it turns out the crank was bent a bit--0.003"-I was about to order a a used a6 crank from someone when I decided to call a local place I heard of-Storm Crankshaft-I asked him if they straighten cranks without grinding he told me to bring it down and they will look at it--long story short--using his hydraulic crank straightening machine, within 15 minutes he got the crank down from 0.003" (which was enough to cause binding in the mains) to virtually zero runout--straighter than a brand new crank!!! He also removed the plugs for me so I can clean out the crap from the passages--he gave me some aluminum tapered plugs which are supposed to be tapped into the holes with a hammer, ground flush, and then peened to seal them up-he said he never had a problem with them coming out (which would mean zero oil pressure-no good!!!) otherwise, to install npt threaded plugs (would have to drill and tap the holes to fit them) would be pretty expensive--so I will just go with the aluminum tapered plugs--has any one ever seen these "plugs" or are familiar with them?

 

If you are in the NY/NJ/CT tri-state area and need a crankshaft straightened, ground, welded, polished or anything else that you can do to a crank--check out Storm Crankshaft in Mt. Vernon, NY--talk to Ray--Great place

 

You did the right thing.

 

get the f!@k out of here.
where have i been

 

511 Homestead Ave
danm i work right around the corner.
i been looking for a crank shop

 

Interesting, was the crank bent running in a motor or do you not know the history on it?

I had the plug ***** removed from my crank, amazing how much **** was in there. It was then tapped and I plugged it at final assembly.

 

It was bent on my last motor--which it came out of--but I was using main bearing clearance of 0.002" and up--the crank guy (Ray) said that sometimes when you take them out--loosening the main caps they take a set and bend--I was going to tap them but these plugs seem ok--they are tapered aluminum plugs, I hammered them in nice and snug and ground them flush--but I just remembered I am supposed to "peen" them as an extra security measure. Yeah, I can't believe you work in Mt. Vernon and didn't know about this guy--truth be told, they are more of a "production" shop--but he knows alot, and I was really impressed by his customer service--he basically saved me time, aggrivation, and quite a bit of money--he also threw in a micropolish--straightened crank, removed plugs and polished for $50--not bad. ALWAYS double check what your machinist says--and if you don't have the measuring tools to double check his work, ask him he can meausure in front of you or try to be there when he does the meausuring so you can see with your own eyes--I almost trusted my (not anymore) machinist--and it probably would have led to a damaged main bearing with the tighter (0.0015") clearances I am using...

 

Why did you run such a large clearances before? They wore to that extent or you didnt know any better?

 

No, I knew better--its sort of a long story--originally I was using a JG block 79mm a6--and the main tunnel was very tight--the crank was avg. diameter--so with standard ACLs I couldn't even turn the crank. So I bought ACL race HX which are (as you know) 0.001" looser--those didn't work either--so I finally got an align bore--and since each journal on the crank was pretty consistent I figured why not use these HXs that I have--because at that point the standard ACLs where too tight and the HXs gave me around 0.0020-0.0022--which I deemed "acceptable"--I didn't feel like (or even have) more money to spend fishing around for (and waiting) for Honda bearings--and I don't even think a red oem bearing is as "loose" as an ACL HX--the only "giveaway" that maybe the clearances were large was a hot idle (850 rpm) oil pressure of 16-17 psi--above 3000 I had 70+ psi