Does Line Honing change the crankshaft's centerline?

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harrisonm

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The way I understand line honing, you shave a bit off the top of the main caps and then hone until the crank holes are perfect. But won't that make the crank's centerline a bit closer to the camshaft's centerline? If so, wouldn't that make timing chains loose and pistons sticking up into the cylinders a bit. Only a few thousandths, but still...
 
Not if it's done correctly. Done right, a very light skim cut comes off the block side. Not enough to change anything, but just enough to clean it up. The main caps are machined down a touch where they meet the block. Then the align hone or boring bar makes the crank bore round again and locates it correctly. When correctly done, it will move the crank center line little to none at all. A LOT of machine shops do not do it correctly, so sometimes you have to tell them how.....or find another shop.
 
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.003 -.005 off caps.

To answer your question:

They sell timing chains that are slighty shorter to compensate for the material being removed.

ROLLMASTER CS5150 – Timing Chain Chrysler Big Block 361/440 PRE/EFI Gold Series with torrington bearing & nitrided sprockets, 9 keyway crank sprocket, 3 bolt cam sprocket – Bill Mitchell Products

"Line Bore Kits available in .002″, .005″, .008″ and .010″. When ordering Line Bore Kits mark order with LB2, LB5, LB8, LB10 after the part number."
 
To answer your question:

They sell timing chains that are slighty shorter to compensate for the material being removed.

ROLLMASTER CS5150 – Timing Chain Chrysler Big Block 361/440 PRE/EFI Gold Series with torrington bearing & nitrided sprockets, 9 keyway crank sprocket, 3 bolt cam sprocket – Bill Mitchell Products

"Line Bore Kits available in .002″, .005″, .008″ and .010″. When ordering Line Bore Kits mark order with LB2, LB5, LB8, LB10 after the part number."

His question was
"Does Line Honing change the crankshaft's centerline?"

It's already been answered. He doesn't need a shorter timing set if the job is done right.
 
The way I understand line honing, you shave a bit off the top of the main caps and then hone until the crank holes are perfect. But won't that make the crank's centerline a bit closer to the camshaft's centerline? If so, wouldn't that make timing chains loose and pistons sticking up into the cylinders a bit. Only a few thousandths, but still...

Exactly -YES . Depends on how much the machinist takes off the main cap mating surface.
I have always used a .005 under chain on blocks I had bored or honed , including 2 hemi`s , a couple of sbc`s , and the is one/ The 440 block I have now , the .005 under chain was so tite I had trouble getting it on/together . Its hanging in there just great .
 
Exactly -YES . Depends on how much the machinist takes off the main cap mating surface.
I have always used a .005 under chain on blocks I had bored or honed , including 2 hemi`s , a couple of sbc`s , and the is one/ The 440 block I have now , the .005 under chain was so tite I had trouble getting it on/together . Its hanging in there just great .


Exactly. It’s going to depend on how far off the mainline is to start with. And if some joker got in there first and did some voodoo magic **** to the mains.

If you have to cut the caps more than .002ish it’s probably going to move the centerline. If you have to take more than about .004 off the caps you should really use the line bore first. Much quicker and easier to keep everything where it needs to be. The more heat you generate the more time it takes to do it right.

I suspect it won’t be long before a CNC line hone is made commercially available. It will have Diamond stones rather than vitrified abrasives and use water based coolant, just like a cylinder hone.

I could be wrong about that, but I do know many shops are now using a profilometer to measure the surface of the main bores. That usually means the OEM’s are going that way and te rest will follow.
 
I had a 340 line honed. The timing chain was as snug a fit as any that hasn’t been line honed. Kim

Yup that's cause they knew what the hell they were doin.
 
His question was
"Does Line Honing change the crankshaft's centerline?"

It's already been answered. He doesn't need a shorter timing set if the job is done right.

I disagreed but only cuz I can't agree and disagree to the same post. You can't line hone the mains without moving the crank centerline a little bit (which is kinda what I heard you saying) but I do agree with you that ONLY if it's done right, it won't change it enough to need a special timing chain set.

That said, I don't know how gear drives compensate for this, even in a production-tolerance situation, let alone after machining. I put the tensioner on the timing chain in my small blocks so I never worried much about any of it.
 
I disagreed but only cuz I can't agree and disagree to the same post. You can't line hone the mains without moving the crank centerline a little bit (which is kinda what I heard you saying) but I do agree with you that ONLY if it's done right, it won't change it enough to need a special timing chain set.

That said, I don't know how gear drives compensate for this, even in a production-tolerance situation, let alone after machining. I put the tensioner on the timing chain in my small blocks so I never worried much about any of it.

Actually, yes pretty much you can. I outlined the procedure very clearly in an earlier post in this thread. Would you consider .0015 (sometimes less) removed from the block side moving the crank center line? It's all relative, because as YR and others mentioned, the block has to be "close" as far as main saddle alignment to begin with......most of them actually are. That's the whole purpose of removing material from the caps where they meet the block. That way, you remove most of the material from the CAPS, virtually leaving the block alone with only the lightest skim possible. This effectively leaves the crank center line the same.
 
Actually, yes pretty much you can. I outlined the procedure very clearly in an earlier post in this thread. Would you consider .0015 (sometimes less) removed from the block side moving the crank center line? It's all relative, because as YR and others mentioned, the block has to be "close" as far as main saddle alignment to begin with......most of them actually are. That's the whole purpose of removing material from the caps where they meet the block. That way, you remove most of the material from the CAPS, virtually leaving the block alone with only the lightest skim possible. This effectively leaves the crank center line the same.

0.0015" is a significant amount when you work with machinists all day like I do, but as I said, it's nothing in terms of a timing chain set.

I've never seen a block blueprint so I don't know what the production tolerances are, but I can't imagine this being beyond factory tolerance!

Edit: I've also always wondered how close to true centerline the main cap surface actually is. It could be off quite a bit and still work.
 
0.0015" is a significant amount when you work with machinists all day like I do, but as I said, it's nothing in terms of a timing chain set.

I've never seen a block blueprint so I don't know what the production tolerances are, but I can't imagine this being beyond factory tolerance!

Edit: I've also always wondered how close to true centerline the main cap surface actually is. It could be off quite a bit and still work.
 
0.0015" is a significant amount when you work with machinists all day like I do, but as I said, it's nothing in terms of a timing chain set.

I've never seen a block blueprint so I don't know what the production tolerances are, but I can't imagine this being beyond factory tolerance!

Edit: I've also always wondered how close to true centerline the main cap surface actually is. It could be off quite a bit and still work.

Right......PLUS, you don't really know where it WAS from the factory to begin with! Was it in "the right place?" Maybe. Maybe not. I'll go with maybe not judging from Chrysler's specs on things like deck height. lol But I agree, from machinist's standards, .0015 is "moving". The thing is, you MIGHT just be moving it into the correct position. You never know. LOL
 
I disagreed but only cuz I can't agree and disagree to the same post. You can't line hone the mains without moving the crank centerline a little bit (which is kinda what I heard you saying) but I do agree with you that ONLY if it's done right, it won't change it enough to need a special timing chain set.

That said, I don't know how gear drives compensate for this, even in a production-tolerance situation, let alone after machining. I put the tensioner on the timing chain in my small blocks so I never worried much about any of it.

It depends on the gear drive. If it’s a 2 gear type Of (very rare) you need an over sized gear. If it’s a 4 gear type (dual idler) they compensate by allowing the idler gears to float between the cam and crank gears. They can move laterally between the crank and cam gears. If it’s a 3 gear type with a fixed idler gear, you can move the plate that the idler gear is fix to a skosh to adjust your gear clearance.

Milodon says to use newspaper but I slap a dial indicator on the gear and slide it over until I get .002-.003 backlash and send it.

If I have to use a timing chain they all get the tensioner.
 
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