Main bearing bore variance after line hone
03-06-2013, 09:37 AM
#11
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.
03-06-2013, 12:29 PM
#12
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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.
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03-06-2013, 03:56 PM
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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. 
03-06-2013, 04:01 PM
#17
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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.
03-06-2013, 10:08 PM
#18
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.
TBC
03-06-2013, 10:09 PM
#19
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.
03-07-2013, 07:17 AM
#20
MarineKinetics
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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
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
