Main bearing bore variance after line hone
 

I have a question about the main bearing bores on my 489 that I am rebuilding. Engine had only 30 hours on it with previous build - had to redo the lower end due to metal from cam spalling.

I was checking bearing clearances this week using a vernier micrometer and a dial bore gauge. Clearances were checked by measuring main journals with the mic, zeroing out dial gauge on micrometer, and then measuring bearings. I got .0026, .0026, .0030, .0035, .0041 front to back.

Questioning this, I pulled the bearing shells and measured the main bearing bores with the caps torqued down to the specified 110 ft lb. I got 2.939, 2.939, 2.9394, 2.9399, which jibes with the variance in bearing clearance readings. These measurements were taken by setting the mic to the low side of the spec for the main bearing bores (2.970) and then zeroing out the mic against it.

This block was supposed to have been line honed when it was rebuilt the first time. Should I be seeing these variances with a proper line honing?

Big question is, does this need to be corrected? We are talking about a normally aspirated, 550ish HP motor that won't likely see the other side of 5500 RPM.

2.937/2.938 is spec. for the mains. Looking at you measurements, it tells me the hones, shoes or stones are tapered allowing the bore size to increase from front to rear. Being the crankshaft journals, measure the same diameter, I would be more concerned about the taper and main alignment of housing bores. I can assure you this, each time you torque the mains, you will come up with a sightly difference in measurements. I would be looking at the wear pattern on the old main bearings, if possible to see if the bearing was side-loading at all. If in question; I would re-cut the caps and re align-hone the mains.

Yeah, I guess I didn't quite get my money's worth on that $250 align hone job with the first build... :(

Wow! $250 to line hone, I charge 125-150, depending what the conditions are at the start. Obviously; that $250 was made without much effort, he could have done 2 blocks for that. That block should have been PERFECT, for that. SORRY

Yep, that's what the ticket said on it. Taking the block to him tomorrow or Thursday so he can mic it in my presence. Lucy, you have some 'splainin' to do!

Please tell us, what his explanation is; for the bore stepping in size. Either the crank is oversize and use a HX bearing, Std, or a for undersize .001, than size the main bearing bores to accommodate the bearing oil clearance you want.

Crank measured 2.743 across the 4 front main bearings. The rear main measured smaller, can't remember the exact number - need to check at home. I think that is generally common for the rear main to have a little more clearance for the thrust.

I would rather get the bores straightened out and within spec so I can keep my standard sized bearings. I should not have to be shelling out more cash for over / underside bearings after paying to have the thing align-honed!

I'd probably make a go of it with x and .001 bearings as needed to get .003-.0032. If you have it re line bored you may need an .005 under timing set or whatever appropriate. That isn't cheap either. It also changes the pushrod geometry a bit. Just food for thought...

Are the x bearings available for the rear main? Seems like I recall reading that these were only for the front four mains. Is the .0041 clearance on the rear main excessive?

I'd do 1/2 shell of x on 1,2 uppers, std on 3 u+l, .001 1/2 shell on 4 upper, and .001 rear upper and lower. Yes you can get x/.001 in all caps. End with .0031,.0031, .003, .003, .0031. You could aslo consider just a half shell of .001 in the upper of the rms if you'd like a little more clearance there. Lots of guys look for .0035 in the rms but I'd rather have say .0032 than .0037 if falling in between.

The bummer about it is that you can't just buy individual shells - pretty sure I have to buy a whole main bearing set of x and .001. That would get expensive. Correct me if I'm wrong.

You are correct, 2 sets. You should verify first tho that the rms line bore in the block is parallel, not tapered front to back. It seems like it could be given your large variances, and if so, you may need to re- line bore anyway. The rear main is so much wider that any taper will be most significant there if the original line bore was of poor quality.

Blue Thunder: Can you explain to me; how line honing the blocks mains, effects push-rod geometry?

I was wondering about that also.

me too.

It doesn't, you guys are right. My brain fart and thanks for correcting it. Funny a while back when I was having my engine machinist line bore a block he said the same thing about pushrods and I corrected him. It will move the pistons up in the hole though.... for the save. :party-smiley-004:

Budman II, I have cut many main caps and rod caps. Line hone mains and resized rods. I would steer away from just buying a -.005 timing set at first. I have found after line honing using a Rollmaster, from Bob Madara, is tight enough. Did you check your main caps to see if the machinist even cut the caps, they should look they have a half of a circular grind pattern on them. If when he is finished, check the parting line to see if, it shows hone cross hatching along with the bore size checking to see if it's over at parting lines.

MER, yes, the main caps have been cut - I can see the mill marks on them. Can also see the hone cross-hatches on the insides of the main bores. So it was definitely align-honed. Just not done right, if my measurements are correct. We shall see what tomorrow brings...

TBC

Related question: how much material is generally removed with an align honing? I was under the impression that the short timing chains were needed when an align BORE is done, not for an align HONE.

Tom,
I would not put forth the effort sourcing bearing options that will bring your I.D. into spec to correct the oil clearance issue. Attempting to band aid poor machining, IE the bearing housing out of spec, will have unintended consequences potentially more damaging than a few tenths oil clearance.
The housing out of tolerance on the high side will reduce bearing crush and the radial force exerted by the bearing back against the housing. This is a key element in both holding the bearing in place and having the correct concentricity of the I.D.
From Clevite:
If you have insufficient crush, the bearing will be loose, resulting in bearing surface polishing or fretting (metal transfer).
The block needs to be corrected or replaced.

Bob

Tom,

Usually a few thousandths; however there are a number of steps necessary to prep the cap for grinding that cannot be overlooked. Lack of proper prep procedures could very possibly be the source of the inconsistencies in your finished housing diameter.

Bob

Bob, I am going to take it over to him to give him the chance to check it in my presence, just to rule out any inconsistencies in my measurements. However, at this point a lot of things are coming into question in my mind, so I may be shopping for another machine shop here in the Louisville area.

I really hope I can salvage the block for this build, because at this point I have already taken the step to file-fit the rings to the bores.

BTW, is the figure that Clevite gave me on main bearing clearances acceptable? He recommended .0032 across the mains. Seems a little big to me.

Thanks for the help!

I use a dial indicator, that was installed in a flat bar, ground flat, for measuring amount to be removed from cap. I measure the cap before and after, only trying to remove .003" to start with. The cap is prepped so no burrs are present to have it setting flat on the bar. This also insures that cap is true in the cap grinder. This takes time and others may not want to exert the effort. As the saying goes; IT WILL BE OK.

Those numbers are good that clevite gave you. You can usually fix the block one way or another. The problem now is can you trust the machinist to fix it right. I've seen line bore jobs screwed up pretty bad. As in over a .001 diff front to back on the rear main bearing surface. What do you think that might do to the crush....

I'm not off that far! I guess I'll find out when I manage to make time to get the block out there.

I have been reading a lot where many builders like to give about .0005 extra clearance across the rear main bearing. Any thoughts on that?

FWIW, I had plenty of oil pressure with it before, but was running 20W50 conventional oil. Would like to run lighter oil this time, maybe 15W40 to try to save wear and tear on the dist gear.

Yes, you do need an extra .0005" at #5 due to the width of the journal. I would give you clearances; I use for specific applications But; it leaves an open door for everyone to argue the issue with.
Your distributor gear in not going to wear out, using 20W50 or if you used 50W, High oil pressure will fail that along with the improper material difference between the cam and gear material. The other issue is; you must insure the distributor gear is centered on the cam gear. either machine the difference to lower it off the flange of the dist. housing hold down flange, if enough material remaining to secure it or buy a slip collar and machine the flange off and set it to the proper height. This works the other way using a thin or thick gasket, I would not stack gaskets, most likely your deck height and cylinder heads are not going to grow, unless you already decked the block or machined the intake flanges.
With the bearing and cam issues you have encountered with this project, did you install new rod bolts and resize the rods along with the rest of the build?
Make sure the galley oil plugs behind the cam gear, have oil holes in the 2 galleys for the lifters .040" to be exact.
Good luck on this, I hope all works out for you, I have seen alot of questions post by you concerning you engine.

[QUOTE=MER Performance;3881862]Yes, you do need an extra .0005" at #5 due to the width of the journal. I would give you clearances; I use for specific applications But; it leaves an open door for everyone to argue the issue with.
QUOTE]

I try to get the .0005 additional on the rear main but never understood why. I totally agree with your not want to open yourself up to debate on what you know works best with clearances. Although I do note a decrease in that type of bickering around here as of late. I also appreciate your approach with me regarding my brain fart above/earlier. You could have taken that as a opportunity to enflame and diiscredit me but you stayed above that. The result is a very informative thread in my $.02.

+ 1

Thanks Mark. The rods (and bolts) were brand new with the previous build - they are Eagle I-beams with ARP cap screw bolts. I never had any spun bearings, and the engine barely had 30 hours on it, so I was really hoping to avoid installing new bolts and resizing the rods. I am going to use a rod bolt stretch gauge to measure stretch on them, and I am also going to measure the big ends to make sure they are within specs. The machine shop did not resize the rods, so there should be no worry about them screwing that up too! ;)

I guess there is the possibility that he king-konged torquing the rod bolts and over-stretched them. Crap, now I am starting to question everything about this build! Catching myself waking up at night worrying about it. :fear:

Tom, If you have issues from one thing on the build, I would always question everything else. It's either done correct within spec. or incorrect out of spec. I have seen many things done of 20 + yrs of business and it gets to the point that it does not surprise you anymore. Never assume that it's correct, check it yourself or go to someone else. If you have lost confidence in your machinist or builder, it's time to move on. There is NO excuse, for incorrect machining practices.
Rod bolts, was a stretch gauge used? If you take a new ARP bolt, lube it and just pull it with a torque wrench, I can guarantee; the stretch will not be maxed, maybe 2-3 cycles. So if that was the case, I would say; they shouldn't be stretched. Eagle, usually starts on the low side. I always, check new rod bolts with a measurement installed, then remeasure them relaxed to see if they stretched the bolts on the low or upper side. Bolts, will measure new .002-.003 difference them, mfg tolerances. Higher end bolts like Carrillo, Oliver 3.5 will be almost same relaxed length.

[QUOTE=blue thunder;3881896]Mr. Blue Thunder, Thank you for that response. This tech. section is for sharing good information, to help others. If someone is questioned about their comment or thoughts, give them a opportunity to answer your question.
I would feel, different about it; if you were trying to always sell something, or promote yourself.

Mark, they torqued the rod bolts to Eagle's specs. Did not use a stretch gauge. I was planning to use a stretch gauge when I install them, and I am going to do exactly what you suggested - measure and record the length of each bolt, and then do a follow up measurement after they are stretched to spec using the gauge. This will be done at the same time I check rod bearing clearances. Of course I will be using the ARP thread lubricant. Any bolts that show more than 0.001 longer will be considered bad and replaced. Does that sound reasonable?

Once the bolts are stretched, meaning from Eagle, or the person that torqued them during the engine build will make no difference on what they read , you will not have a accurate length. As I said; those bolts will not even measure the same length NEW. What I am telling you is; when I receive, new rods; I use the stretch gauge, set it to zero, remove gauge, loosen bolt, slide stretch gauge over bolt, then read how many thousands the gauge indicates. This is telling me; if the rod mfg, set the bolt stretch to .005 or .006. This is only for the simple reason either for me to know; if the stretch was low and I want .006 or they made a mistake. I will have the rod torqued properly, check it against the rod gauge on the hone for trueness and re-hone it if needed.
A Eagle rod, is what it is; it's not a cheap item nor is it junk. I have used plenty of them with no issues; but you must check sizing of the big end and the bushing end. Alot of times the bolts are under torqued, if you increase bolt stretch, they will distort, wrist pins are usually alittle tight, but the bushing material is more forgiving than a Ampco 45 bushing. When you buy $1200.00 rods with special bolts, better bushings, pin oiling, that cost goes into what you receive in the end, not saying I do not inspect rods from Oliver, Carrillo, I do; they just do not need any touch up work.
If you are worried about the bolts being over stretch, you can usually tell by the way the torque wrench pulls before you reach the max stretch. If it pulls easy; like the bolt is a rubber band, with no increase in tension; I would say; it's over stretched. If the guy used a torque wrench at the torque setting they gave, I am willing to bet he didn't over do it. You will be surprised to see what your torque wrench has to go to for maxing out the stretch number. Sorry for the rambling on!

I'm not particularly worried that they were overstretched. I'm slightly concerned that if they were understretched from the factory and I stretch them a bit more that the bore could distort. I'll have to go back and look at my old rod bearings again to see if there is any evidence of bore distortion, but i don't recall seeing any. Would I be able to detect the bore distortion with my bore gauge?

At this point maybe the best move would be to torque them to the value that was used with the first build. Thoughts?

Yes, you can with the bore gauge. Using the Sunnen AG 300 on the hone is just more precision and convenient. Most of the distortion, will be at the parting line. Just remember; if you check the rod or main bearing torqued into a perfect round bore, the bearing is always going to have more clearance as you come towards the parting lines, otherwise the oil would not flow properly around the surface and flush. Bearing crush, and the bearings back contact surface, with the bore is what we are trying to achieve with a smooth true surface.
I have seen rod caps cut on a belt sander, bearing bores oversized on rods to give oil clearance instead of using an HX bearing and this is something someone did on a NEW set of Manley rods to compensate for the cranks rod pins being oversize, the main bores were over sized using Std H bearings instead of HX. STUPID, STUPID, STUPID!!!!!! Don't feel bad about not knowing this, it's like going to the doctor, you are putting your trust in someone that is suppose to be a professional, at their job. Charge for test that are not needed, perform surgery, take out the wrong thing and leave tools in you. You get sick after the surgery, bring you back in again, and charge you, then blame it on you.

are you saying that you are using a stretch number based on the preloaded length as the rod comes out of the box from the mfg minus the free length of the bolts when you disassemble it ? you are presuming the mfg is sending you the rods " torqued " to spec ? and that your observed stretch is the true stretch spec for that bolt ? all my stuff came with that spec in the documentation that came with the rods and i never assumed that the rods coming out of the box were anything other than just assembled to keep the parts from falling apart during shipping...

beyond that , you imply that your bolts change dimensions from one assembly to the next... if this were true then they are being strained ( stretched) beyond their elastic limit ( yield ) and are effectively scrap once that happens. on a good bolt , propery stretched to its correct preload, you should be able to do that essentially as many times as you care to and have that free dimension repeat plus or minus nothing. all parts like this have a cyclic service life and you are going to see different dimensions start occuring on bolts nearing the end of their service life as they yield at lower strain levels but new stuff, properly lubed and stretched should be repeatable every single time. if they don't then something is very wrong.

Maybe, my explanation was not as clear as I meant to say.
Lets start over; I have never received rods from Oliver, Eagle, Compstar, Carrillo, Crower, that the bolts were backed off, after final honing to size. The rods are sized with the torque load or bolt stretch applied. Example; if the stretch is .0055-.0064, how do you know what it is; if you do not measure the bolt before and after separation or are you just relying the spec. sheet ? This is something I check; go check at rod sized at .005 stretch then take it to .006, than check on a precision rod gauge and let me know if; there is a deflection. Or take a rod that the bolt was not stretched to even .005, hone it; than stretch it to .005 or .006 and see how the deflection is. That was my only point.
Dimension wise on the bolts meaning O.A.L. never stretched say; 8740, L-19, ARP 2000 take your stretch gauge zero it, or use a ball micrometer, see if all the bolts measure the same exact length.
I think your other question was bolt yield? Yes; the rod bolts will become easier to reach there stretch or final torque setting after the bolts were cycled about 3 times. I think; the non stretch gauge method from ARP installing new rod bolts was cycle the bolts 3 times like on a 3/8 or 7/17 style bolt that is pressed in then you tighten the nut, if you are not using a stretch gauge.
When I was speaking of dimensions; it was in reference to Budman II, main bearing caps. When we line hone the block and you want to bring in the sizing on the bores and say; 1 or 2 mains are close to size, we back off the torque load, than re torque them again. It always seems that the bore size will tighten up once you break the bolts loose than retorque them of course this is true if the bolts are over or under torqued. You can check this; take a main cap, torque it, 3 different times and see if you come up with the same exact measurement.
I hope this clarifies, my statements. If you have anymore questions about my statement, please feel free to ask. I am not a metallurgical engineer, I was only expressing my experience from the last 23 yrs of business.

i am just surprised you trust the preload as delivered. seems to me that thats just another way to build on top of someone elses mistake. if the spec sheet says .0045 stretch, i just backed them off, re lubed them, stretched them what the defined number was and made my measurments. and that worked for me for better than 20 years as well.

stevesxm,
If Iam; checking the pre-load. Where does, trusting it come into the picture and or building on top of someone else's mistake If you want to back up your bolt stretch; that's is up to you. If I wanted the bolt at the lower # of the bolt stretch, I would leave it. If I want the bolt stretch @ almost the max. I will set it there and check the bore run-out.

If; I have made a false statement about bolt stretch or bore dimension. Please inform me, for I am not following the point you are putting forward to me.

Mer Perf, don't let stevexm get you going. He likes to debate and you will surely tire before he does. There really is no point and you will just end up POed for no reason. Pretty much what I was alluding to earlier. I surely appreciate you sharing your insight into the machine work tricks of the trade and would like to see it continue. A word to the wise is sufficient...