It doesn't. Thanks for giving a brief background to help the forum understand the reasons behind your frustrations. The vertical clearance is the one that matters. There may be a certain amount of eccentricity engineered into that bearing, so for now I'd disregard your X dimension until you find out more info. What remains is that you are 2 tenths tight on the vertical clearance. Was this bored or honed? Was the intent to clean up the main line without moving the crank centerline closer to the cam, and therefore certain strategies or tactics used that might leave an out-of-round condition as a known risk? For example, I'd consider putting up with an out-of-round bore in the direction of the intended eccentricity to prevent further migration of the crank's centerline. You can see why I'd call things into question. If you know what you are dealing with, why would you lead yourself down that path? Hopefully your project turns out in a way that keeps you happy.
I don't think your ever going to get that engine together, there is always going to be something wrong You would be much happier if you just buy a crate engine and put it in your car and then you can drive it I know its a bit sloppy, but I didn't even "plastigauge" my crank after it was machined, just put it together and made sure it turned, it did, and its still turning now
Thank you for your reply. Im under the impression that the HOUSING BORE should be perfectly circular, thats The MAIN HOUSING where the bearings reside, NOT the bearing ID. Im aware the bearings ID are manufactured to be eccentric, and the Vertical (Y) Axis is the number I should be concerned with for Oil Clearance. The Main Caps WERE cut, and then the Housings/caps were Align Honed against my wishes... Lots going on in the thread- easy to lose pace especially looking back. Earlier in this thread I believe I made mention of the caps being cut, but yes.. Original shop went against my wishes and Align Honed. Now, the Housings are NOT Concentric- 2 thousands loose Horizontally, yet as you mentioned- marginally TIGHT, Vertically. .002 LOOSE Horizontally! Unless all I DO know about this is rubbish, that just isn't going to cut it.. Thats the Bore which holds the bearings tight to prevent spinning, and its too loose.. Am I shooting for Perfection? Yes. Will Everything be that way? Probably not. What I AM shooting for ultimately, is RIGHT.. And Main Housings that are not concentric, along with LOOSE oil clearances measured so far is NOT RIGHT. I agree.. I do not want the crank potentially moved any further up the Y axis any more than it probably already has. REALLY starting to think my best bet is to roll with .020 Under and start fresh. Maybe get the bores "Round" by Align BORING, focusing the efforts towards the caps? Grind the Crank "on the high side" for the .020 bearings for the desired .002~ Clearance? Starting fresh in that regard seems like the best bet without disturbing other work performed- like my Zero deck, Balance, etc..
NOTHING will make me happier than building this old Nailhead up right, and enjoying it for years to come! Regardless of how hard the struggle has been, it WILL be worth it, and I WILL get there! Slowly...
Agreed, I was leading you to a potential solution that doesn't involve replacing the block or machining some type of insert requiring a radical amount of material removal. Sounds like new block time if you aren't willing to live with it. To shrink the parting line axis enough to give you a perfectly round hole will require removing .060-.070" from the mating surface, which is well beyond the scope of line boring to fix the problem. The timing chain would certainly be an issue if moving the crank centerline even half that. You could cut the cap side only and deal with the extra eccentricity on the block side, but I don't think it will affect the heat transfer or fit of the shell...or oil pressure any more than just installing your bearings. You could also measure up several sets of bearings and pick the ones with the least eccentricity, being that the vertical clearance is a couple tenths tight (you would restore what you perceive as 'too much clearance'). Maybe measure the rest of the bores with the understanding that the front main sees oil last anyways, before making any decisions. I'm going to defend the shop on the align bore outcome (not doing it against your wishes though)...the hone didn't likely create the OOR condition, it merely followed what was already there. It was OOR and oversized along one axis already. There wasn't enough material in the block to do it without it happening. You gave them a junk block by YOUR standards. Even an inexpensive caliper should have found that prior to honing. (I understand the struggle of selling tools and shop closings) Grinding the crank again isn't going to do anything to help your issue, the problem is the block. You wouldn't be disturbing balance any. The deck surface isn't off enough to worry about anyways. Next time grind your crank last, after you measure up the installed bearings. You should know better :beer . I hope you don't take my post as harsh as it seems to read. I had suspected you had a certain amount of machining experience and felt the need to assign some responsibility where it should lie. All you can do is move forward.
None of this was taken harshly, guys. :beer It always seems like a good idea to hear from as many folks as possible for solutions or input. I'll be chipping away this week when I can at those numbers/measurements. Are you guys saying to not be so concerned with the out of round/eccentric Main Housings? I can see how that "Could" be scoffed at, as the Bearing ID is eccentric by design. However, from what I know, in my mind, the perfectly round OD of the bearing should be in a perfectly round housing to prevent slipping/spun bearings. More "bite" if you will, if its in the tighter OD I'm trying to achieve. How about that rather loose .0028 Oil Clearance? A tad big? I was shooting closer to .0020, not 3! My thinking was that the .020 UNDER BEARINGS would tighten that clearance up, of course with NEW crank-grinding to the newly installed .020 Bearings.. I know new bearings won't help the actual HOUSINGS.
Check every bore to see where you are at before you think about another block. I personally wouldn't spend a red cent on machining to tighten that up .0008", esp. if it's only one bore. Look at how they all add up, another concern is taper and bellmouthing. It isn't unusual to require swapping the block around end for end while in the hone. You 'could' buy a few more sets of bearings to either swap shells around or whatever works for you...maybe sell the still new ones on Ebay. The potential for failure due to lack of crush would be more concerning than a few tenths of vertical clearance. You'll never see that on a pressure gauge or detect signs of failure upon later teardown and inspection. You could always sell this block to a guy that might run it hard enough to consider it expendable. Call it a drag racing block. In non-perfect situations, it isn't unheard of to 'hone' the mating surface of the cap .0005" to increase the crush and tighten up the vertical clearance. (I doubt the crush is lacking) I can't suggest being concerned or not...only offer up solutions. I'd probably use the block if it were my personal driver, but then again maybe not tell the entire world(?) :laugh::laugh: I do have an expendable corporate motor in my firewood truck with very loose clearances and one main cap that I've hand stoned that I absolutely thrash. It pegs the oil pressure gauge and tolerates every bit of apathy I dish out...but like a moped, I don't tell all of my friends about it. Curious how this one gets solved... [I didn't originally catch just how loose the vertical clearance was, only the block bore. It just says, "Was shooting for a bit tighter"]
I was "shooting" for a tighter oil clearance. #1 is .0028 Oil Clearance mainly because my crank is cut smaller than spec... The more Im able to measure... :/ Doesn't change the fact that the housing is OOR The most jarring thing I've seen still, is the Housing Bore. X is too big by .0022 Y is tight by .0002
I an not sure what is available for the Nailhead since it was last manufactured 50 years ago and it is not an LS or Mod motor, but bearing companies often make bearings in .001" sizes up or down to correct for the clearance issue you described. You might try TA Performance to see of they have any. Maybe there are some NOS on Ebay or elsewhere. At least you could correct the main bearing clearance issue that way. Cheryl
I still see what you are saying about the housing bore, this isn't a new problem to me. You can either A. Get a new block B. Deal with it in some way, with the bearings that are available C. Machine out the entire area for a new main saddle or some other creative thing. I guess you have to decide what is a bigger priority. I can tell you that many, many things are far from perfect in every engine. (For example, what is the true flatness of a deck surface when almost all shop's spindles are tilted to prevent back dragging because there wouldn't be enough travel in the machine otherwise? What is the dimensional accuracy when it's full warm and running under load? How about when the torque output is doubled?) The bearings already have some eccentricity in them, so that opens up a line of thinking. *You haven't even measured the rest of the mains to have a bigger picture to decide upon yet.* I'd probably see how bad the rest of it was before getting too wound up. I'd be curious to see the machining marks on all the bores in the main line.
Maybe measure the thickness of the bearings at the 'Y' point. I wonder if the production tolerance is better than 0.0002"
They USED to make bearings in + or - .001", but at the time for the RODS only. Drastically doubt if ANY could be found in today's market. Another option would to be, once you get the dimensions correct, is to use .001" brass shim stock under the bearing lower shell. For one reason or another have put together race engines this way WITHOUT a problem as far as longevity or performance. Just another thought. Tom T.
^^^^ Have seen that before during a disassembly. Thinking it was a motorcycle engine from the factory. Or maybe my fathers international backhoe engine. I will have to ask him at thanksgiving now that I am thinking about it. Cheryl Sent from my iPhone using Tapatalk
^^^^^^ Have done it. It's the way things used to be before they made +- bearings. I wouldn't be afraid to do it for my own stuff if there really was no alternative, but wouldn't suggest it to someone else, especially openly in a forum where the OP has a strong statement towards "doing things right".
How about applying a dry film coating to bearings to reduce oil clearance! Techline's "DFL-1 typically will be applied in a film thickness of from .0003" to .001" " http://techlinecoatings.com/articles/Coating_Bearings_Article.htm Main bearings were once avail in 0.001" undersize but I've never seen them in 0.011 or 0.021". Be aware 64-66 bearings have a wider flange on the thrust bearing, unsure if the will fit the early blocks. For NOS 0.020" bearings, you can try Johnsons Speed Warehouse: https://www.facebook.com/pages/Johnsons-Speed-Warehouse/159058860781828 There are some NOS 0.020" bearings on eBay but they're $320. Rod bearings are the same as 455 so there is much wider availability. Jim Weise has discussed main bearing bore sizes in 455 threads. Good general info.... if you can find the thread.
It was an excellent thought! It flat out works. I'm guessing the market has gotten away from those practices because it's easier to install an insert. So many things have gone by the wayside with our disposable world. I hadn't covered everything because I think the OP will end up using a different block. It's not likely the main line is going to be machined out for a cylinder sleeve to be pinned into place as 'fresh stock' to tighten up .0011" on each side of a parting line when a bearing is already eccentric :grin:
No defense needed! If some factories and machine shops were using this method considering the liability and possibility of return, it qualifies as "doing things right." When have you ever heard of an engine failure due to a bearing shim? I think Will is on to a nice build. Maybe we can help him compromise on some things that will not detract from the strength or quality of his build while allowing him to move forward with what he has. Cheryl
