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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / August 2007

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Line Honing Q

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ray - 17 Aug 2007 04:05 GMT
The engine is a small block Chevy, for my dirt track Camaro.
Last season I ran it out of oil (pan damage) and the machine shop had to
line hone the block as part of the rebuild procedure.

Now, the timing chain (stock GM) seems a bit loose - not horribly bad,
I'd probably use it on a street car, but not good enough for a race
application.  Picking up a new double roller set tomorrow, but when you
line hone a block, does that move the crank closer to the cam or does it
keep it the correct distance away?

I'm guessing that distance doesn't change or you'd run into all sorts of
other problems, and the chain just stretched from abuse, but I thought
I'd ask...

Also, how much of a nick is allowed on an intake valve stem before it's
junk?  Probably none, eh?  <sigh>  Good thing I have VISA. ;)

Ray
Steve W. - 17 Aug 2007 04:50 GMT
> The engine is a small block Chevy, for my dirt track Camaro.
> Last season I ran it out of oil (pan damage) and the machine shop had to
[quoted text clipped - 5 lines]
> line hone a block, does that move the crank closer to the cam or does it
> keep it the correct distance away?

Moves them closer by whatever amount they had to remove to get the bore
back to spec. Usually they shave the caps and try to take as much as
possible from the cap to keep the change as small as possible. The
difference isn't usually enough to matter as ANY timing chain will
stretch farther than the line hone difference anyway. Even a new chain
in a new engine has some play.
If your worried get a gear drive set-up unless the are outlawed.

> I'm guessing that distance doesn't change or you'd run into all sorts of
> other problems, and the chain just stretched from abuse, but I thought
> I'd ask...
>
> Also, how much of a nick is allowed on an intake valve stem before it's
> junk?  Probably none, eh?  <sigh>  Good thing I have VISA. ;)

For the price of a valve, toss it. Nasty things happen if a valve breaks
when your on the final lap and sitting out front....

> Ray

Signature

Steve W.
Near Cooperstown, New York

ray - 17 Aug 2007 05:42 GMT
>> The engine is a small block Chevy, for my dirt track Camaro.
>> Last season I ran it out of oil (pan damage) and the machine shop had
[quoted text clipped - 13 lines]
> in a new engine has some play.
> If your worried get a gear drive set-up unless the are outlawed.

Thanks.  It's not that bad of slop, but it kind of reminds me of what
you'd see on a 100,000 mile engine for play, so a $30 replacement timing
chain is going in.

>> Also, how much of a nick is allowed on an intake valve stem before
>> it's junk?  Probably none, eh?  <sigh>  Good thing I have VISA. ;)
>
> For the price of a valve, toss it. Nasty things happen if a valve breaks
> when your on the final lap and sitting out front....

I know... it's actually less of a $ thing than a time thing.  This year
everything car related is taking 3x as long, and with a 2 year old and a
5 month old, I'm getting 1/3 the car time, so things are going really
really slow.  There's only 2 races left for me and the motor is still
torn apart, I need to change a balljoint, and replace my belts.  I got a
trailer this year, only took 10 hours to wire up the truck... it should
have taken about 2 hours because the truck was mostly wired up - one
missing fuse and one bad connection took most of the time to diagnose.

Ray
ray - 17 Aug 2007 06:05 GMT
>> Also, how much of a nick is allowed on an intake valve stem before
>> it's junk?  Probably none, eh?  <sigh>  Good thing I have VISA. ;)
[quoted text clipped - 3 lines]
>
>> Ray

Hey, silly question - do I have to lap a new valve in or can I just swap
it?  The heads are like new, they only have about 300 race miles on
them, so the seats are good, I just noticed one nick in one valve stem
when we pulled one spring off to check, so now I'm going to check ALL
the valves in both heads...

It's been a long time since I did any valve jobs in school...

Ray
Steve W. - 17 Aug 2007 06:26 GMT
>>> Also, how much of a nick is allowed on an intake valve stem before
>>> it's junk?  Probably none, eh?  <sigh>  Good thing I have VISA. ;)
[quoted text clipped - 13 lines]
>
> Ray

Well the current school of thought is that if the seats are cut properly
you don't need to lap. BUT I still would rather lap them to make sure I
have a good seal. It's even relaxing to just hear the click of the
lapping tool...

Signature

Steve W.
Near Cooperstown, New York

Steve - 17 Aug 2007 15:17 GMT
> The engine is a small block Chevy, for my dirt track Camaro.
> Last season I ran it out of oil (pan damage) and the machine shop had to
[quoted text clipped - 5 lines]
> line hone a block, does that move the crank closer to the cam or does it
> keep it the correct distance away?

Line boring moves the crank closer to the cam, there's no other way to
do it. Material has to be removed from both the block and the bearing
caps (the "legs" where the caps bolt to the block are shortened and then
the caps are bolted in place leaving the crank hole "oval" its then
bored back round, removing material all around. The machinist should set
up the machine to remove the MINIMUM amount of material from the block
side, but some will be removed.

IF the timing chain is noticeably sloppy, then the block may be getting
to the point it can't be used much longer (too much upward movement of
the crank required to clean up the block). But another option would be a
gear drive for the cam, which usually has adjustable tensioners.
Mike Romain - 17 Aug 2007 16:15 GMT
> The engine is a small block Chevy, for my dirt track Camaro.
> Last season I ran it out of oil (pan damage) and the machine shop had to
[quoted text clipped - 14 lines]
>
> Ray

I could be 'way' off here, but....

When they rehone the crank journals or even rebore them, the center line
of the crank stays put.  The Main bearing journal size simply changes
and you buy a bearing to fit it.

They don't 'move' the crank.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's - Gone to the rust pile...
Canadian Off Road Trips Photos:  Non members can still view!
Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590
(More Off Road album links at bottom of the view page)
ray - 17 Aug 2007 16:53 GMT
>> The engine is a small block Chevy, for my dirt track Camaro.
>> Last season I ran it out of oil (pan damage) and the machine shop had
[quoted text clipped - 29 lines]
> Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590
> (More Off Road album links at bottom of the view page)

fwiw, I'm going to call the machine shop today to ask them about this -
I figure they'll either be able to set me up with the right size of
timing set, or confirm that my timing chain is just a bit stretched.

In high school (way back when) I was told that if you put the chain flat
on a workbench and the top drooped far enough to touch the bottom, it
was worn.  Now, this may only apply to traditional V8's up to the 70's I
dunno, because we swapped the timing chain on the wife's Beretta V6 back
in 99 and the new one was just as saggy as the old one.  (We were
swapping it for cheap insurance while I had the motor out to do a tranny
swap.)

The motor has not been rebuilt before - it was a new GM Goodwrench 260HP
longblock I bought in 2006 for my race car.  I had a fancy oilpan on it
with baffles and trap doors and stuff, but one of the baffles came off
and left 4 spot weld size holes in the sump, and it's a dirt car, so no
one can see you leaking... and when I lost oil pressure and shut the
motor off, there was probably less than a quart in the pan.  The
bearings were literally melted and the crank and 6 rods were smoked.
You can actually see the blue on them.  We put new higher compression
(legal for the class) pistons in there, and they line honed the block to
clean up the slight warpage that was in there.  Everything else was
good, they didn't have to deck it or anything - the pistons are a
standard bore size - there's not even 300 miles on the motor...

Ray
Steve - 17 Aug 2007 17:03 GMT
>> The engine is a small block Chevy, for my dirt track Camaro.
>> Last season I ran it out of oil (pan damage) and the machine shop had
[quoted text clipped - 22 lines]
>
> They don't 'move' the crank.

You're way off ;-)

Line-boring works this way:

The first step is to "shave" the main bearing caps a prescribed amount,
so that when they're re-attached to the block, the bearing retaining
circles are no longer circular. Viewed end-on, they're all "football"
shaped (sorta) since a thin slice has been removed from the center of
the bearing circle.

After the caps are attached to the block and torqued to spec, the boring
bar is set up so that (ideally) the "new" bearing circle is just exactly
tangential to the old bearing circle at the very top of the circle (the
block side). Of course that wold mean that the only material to be
removed comes off the caps, and the crank wouldn't be moved at all.

But, you only line-bore for a reason, and that reason is frequently
damage to the block casting and caps from a spun bearing. If that is the
case, you HAVE to remove some material from the block in order to remove
the damaged metal, and therefore the crank centerline does move up ever
so slightly. The actual movement is on the order of a couple of
thousandths of an inch, so its pretty negligible. It does affect the
cam-to-crank spacing, and also moves the pistons up in their bores by
cos(45)*the amount of material removed (for a 90-degree V-block engine),
but again that's pretty trivial because numbers like that are generally
less than the variability in the amount the head gasket compresses anyway.
Mike Romain - 17 Aug 2007 17:51 GMT
>>> The engine is a small block Chevy, for my dirt track Camaro.
>>> Last season I ran it out of oil (pan damage) and the machine shop had
[quoted text clipped - 26 lines]
>
> Line-boring works this way:

I understand what you are saying, but when I rebuild engines I have to
buy the correct bearing for the journal 'diameter'.  Even at the factory
they hone the bearings to different sizes in different blocks which
takes material off 'both' the cap and block side of the hole.  The
center line isn't affected.

For instance on one Jeep engine, the main bearing diameters can be
anywhere from 2.4901" up to 2.5001".

These stock bearings are even color coded and the block stamped for
their 'factory' over and undersizes.

The OP only had his honed, not rebored as well.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's - Gone to the rust pile...
Canadian Off Road Trips Photos:  Non members can still view!
Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590
(More Off Road album links at bottom of the view page)
cuhulin@webtv.net - 17 Aug 2007 19:14 GMT
Use some Plastigage and determine what the limits are.Now, if my old
walk behind trustry Briggs & Stratton engine lawn mower had/has a nicked
valve, I would push it till it croaks and then go buy a new Briggs &
Stratton engine lawn mower for about a hundred bucks.I have no idea
though of what condition (my condition is in) the old valves in my 1978
Dodge van are in.sometimes, when I crank it up, they make a racket,
sometimes not, quiet as a church mouse.That's just the nature of those
old Dodge engines though.
cuhulin
Steve W. - 17 Aug 2007 21:56 GMT
>>>> The engine is a small block Chevy, for my dirt track Camaro.
>>>> Last season I ran it out of oil (pan damage) and the machine shop
[quoted text clipped - 47 lines]
> Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590
> (More Off Road album links at bottom of the view page)

Mike there is a BIG difference in grinding the crank and grinding on the
block. The crank is ground on a machine using the original center of the
crankshaft. The new bearings are physically thicker INSIDE the shell to
make up that difference.

However when you line hone a block you CANNOT use the original bore that
the factory machined for the crankshaft. Either damage or wear has made
that bore out of round or tapered or just FUBAR. It is now too large for
the factory bearing shells to fit in. Nobody makes a set of bearings
that have a larger diameter to fit that hole. You need to make the hole
smaller AND round to bring it back to the factory size.

http://www.eddiesvalvegrinding.com/boring-honing.htm

Signature

Steve W.
Near Cooperstown, New York

Mike Romain - 17 Aug 2007 22:36 GMT
>>>>> The engine is a small block Chevy, for my dirt track Camaro.
>>>>> Last season I ran it out of oil (pan damage) and the machine shop
[quoted text clipped - 61 lines]
>
> http://www.eddiesvalvegrinding.com/boring-honing.htm

My Jeep engine's bearing specs clearly have the 'different' journal size
(diameter) measurements I gave above and the bearing insert measurement
for the different crank sizes.

To quote your link even:

If an engine overheats or loses oil pressure, one or more bearings on
the crankshaft or camshaft may seize and spin. The resulting damage to
the bearing bore must then be repaired by either machining the hole to
accept a standard sized bearing or an oversized bearing.

And:

Many engines can handle a few thousandths variation in the position of
the crankshaft centerline but others cannot because of changes it causes
in other critical dimensions

End Quote

I think if they end up having to move the crank more than a hair, the
engine is trash.

Mike
Steve W. - 18 Aug 2007 05:13 GMT
> My Jeep engine's bearing specs clearly have the 'different' journal size
> (diameter) measurements I gave above and the bearing insert measurement
> for the different crank sizes.

For different crank journal sizes YES. If the BLOCKS bearing bores are
oversized your SOL. The oversized bearings you get for Jeeps are ALL the
same external size. They are different on the inside only. You mic. up
the different journals and use undersized bearings to give you the
correct clearances.
For instance a SBC uses a block with the mains bored to 2.6406-2.6415.
The bearings are made so they fit a journal diameter of 2.450. Now if
you grind the crank to .010 under. The bearings STILL have to fit that
2.64 hole, but they will be 2.440 on the inside. You can sometimes find
bearings in .001/.002 undersizes as well. They are still made to fit in
that 2.64 bore.

Same thing with your Jeep bearings. The undersizes are to fit worn
crankshaft journals. The bore in the block still has to be the correct
size or the bearings will be loose and spin.

> To quote your link even:
>
> If an engine overheats or loses oil pressure, one or more bearings on
> the crankshaft or camshaft may seize and spin. The resulting damage to
> the bearing bore must then be repaired by either machining the hole to
> accept a standard sized bearing or an oversized bearing.

True. However the meaning is that you correct the block back to the 2.64
size so you can install new bearings that fit the crank. If you use a
new crank you use standard bearings, if you cut the crank you use an
oversized bearing.

> And:
>
> Many engines can handle a few thousandths variation in the position of
> the crankshaft centerline but others cannot because of changes it causes
> in other critical dimensions

Also true. GM specs allows a centerline difference of +/-.004 from the
factory. However you still try to minimize the loss. On a couple
Chrysler engines the allowance is only .001.

> End Quote
>
> I think if they end up having to move the crank more than a hair, the
> engine is trash.

Not really, on the Jeep straight 6 they allow a difference of +/- .006

> Mike

Signature

Steve W.
Near Cooperstown, New York

Mike Romain - 18 Aug 2007 12:58 GMT
The book for the Jeep engine 'clearly' states the different 'oversizes'
are for the 'main' bearings, 'not' the crank to rod bearings.

It also 'clearly' gives different codes for @1 main and # 2 to # 6 and
then #7 or the rear 'main' bearing.  (engine has 7 mains)

These are 'oversize' codes for the different journal 'diameters' as I
mentioned earlier.

It then gives 'undersize' codes for how much you cut off the turned crank.

If the Jeep engine is allowed .006 for a crank center, how thick is a hair?

Later, off camping.

Mike

>> My Jeep engine's bearing specs clearly have the 'different' journal
>> size (diameter) measurements I gave above and the bearing insert
[quoted text clipped - 46 lines]
>
>> Mike
Nate Nagel - 18 Aug 2007 13:37 GMT
> The book for the Jeep engine 'clearly' states the different 'oversizes'
> are for the 'main' bearings, 'not' the crank to rod bearings.
[quoted text clipped - 12 lines]
>
> Mike

A hair is about .003-.004 inches.  Of course, this depends on race and
individual differences, notably follicular condition :(

nate

Signature

replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel

Steve W. - 18 Aug 2007 14:53 GMT
> The book for the Jeep engine 'clearly' states the different 'oversizes'
> are for the 'main' bearings, 'not' the crank to rod bearings.

That is what I have been talking about the MAINS.

> It also 'clearly' gives different codes for @1 main and # 2 to # 6 and
> then #7 or the rear 'main' bearing.  (engine has 7 mains)

Yep, and using those bearings requires you to grind iron off the crank
(NOT the block) so they fit.

> These are 'oversize' codes for the different journal 'diameters' as I
> mentioned earlier.
>
> It then gives 'undersize' codes for how much you cut off the turned crank.

Notice they tell you to cut the CRANK not the main bores in the block.

> If the Jeep engine is allowed .006 for a crank center, how thick is a hair?

Depends but the supposed "standard" human hair is .004".

> Later, off camping.

Enjoy.

> Mike

Signature

Steve W.
Near Cooperstown, New York
NRA Member
Pacifism - The theory that if they'd fed
Jeffrey Dahmer enough human flesh,
he'd have become a vegan.

Mike Romain - 21 Aug 2007 18:26 GMT
Geese guys.

It 'clearly' states the 'cylinder block' outer main journal diameter can
vary 0.010" and you buy stock bearings to fit.

These bearings come in sizes from 2.4901" up to an outer diameter of
2.5001".

It also states the stock 'crankshaft' main journal diameter is 2.2988".

This gives a whole bunch of 'honing' or reaming room without having to
change or dick with the centerline seeing as even being out a hair is
bad news for most engines.

Mike

>> The book for the Jeep engine 'clearly' states the different
>> 'oversizes' are for the 'main' bearings, 'not' the crank to rod bearings.
[quoted text clipped - 25 lines]
>
>> Mike
Comboverfish - 19 Aug 2007 06:01 GMT
> The book for the Jeep engine 'clearly' states the different 'oversizes'
> are for the 'main' bearings, 'not' the crank to rod bearings.
[quoted text clipped - 12 lines]
>
> Mike

Mike, here's how it is...

Rod and main bearings for normal auto engine overhaul purposes are
sold as either "standard" or "undersized" (not "oversized").  The term
refers to the inside diameter of the bearing or the outside diameter
of the crank journal.  They are sized to the crank pins, and in some
OEM situations, a factor of both the crank pin *and* main or rod
journal, but that is not appropriate to this discussion.

The OP is talking about a normal engine rebuild situation using either
a standard sized new crank or a crank turned to some undersize.  We
don't know what size as it hasn't been disclosed, but it doesn't
matter anyway.  The block main journals were trashed and needed to be
line bored/honed to get them back in alignment and back to the correct
diameter.

This is how the Chevy engine rebuild went for the OP.......  The
diameter of his main journals is supposed to be... well, lets say 2.5"
for a point of reference.  The OP brings in his messed up block to the
machine shop.  The machinst IDs the block and looks up the correct
journal size in his reference book.  He starts by taking some metal
off the mating surfaces of the block and the journal caps, then he
runs the bar through the (assembled) caps/holes until the diameter is
once again exactly 2.5".  This moves the crank centerline a hair
closer to the cam centerline; there is no avoiding this assuming that
some of the block side metal was damaged from spun bearings.  He can't
do this operation properly without cleaning up the damaged surface on
the block side of the journals.  Whether the operation is being done
to correct a misaligned crank or to clean galled metal it *will* bring
the crank closer.

Now that he has his block back he needs to put a crank in it.  If it
is a new crank and machined accurately, standard bearings will do.
They will always be 2.5"-ish outside diameter and about 0.0015" larger
than the crank mains on the inside.  If the crank has been turned
undersize, then the correct fitting undersized bearings will still be
2.5"-ish outside, and about 0.0015" larger than the undersized
journals on the inside.

You mentioned your Jeep straight 6 having different types of main
bearings.  Sure, that is the norm.  The thrust bearing will be
different, and sometimes the rear main and/or the front main will be
different depending on engine.  I have yet to see an engine that has
more than three different types of main bearings, but there's no
reason that all of them couldn't be different.  Unfortunately, if they
have different diameters, line boring becomes more difficult.  The
same concepts as above are still true though.

I mentined some bearing sizing methods that take the block and the
crank into consideration.  On these types, including the 4.0 IIRC
(rebuilt one at a Chryco dealer in the '90s) you take stamped numbers
on the crank and block and reference them to a chart to find the
correct insert.  This does allow you to fit an insert that is sized
both externally and internally (sort of) to a FACTORY UNTOUCHED crank
and block.  Once you machine either part then that is all thrown out
the window and you simply use standard or undersized bearings either
from the dealer or aftermarket.  Since the OP is taking about a
(re)machined engine this type of measurement doesn't apply.

If you are worried that the block mains and the new bearings aren't a
perfect fit together, you can always verify the installed bearing size
with a snap gauge or plastigage.  If that measurement isn't the
correct mate to it's respective crank pin, then either the bearing is
made wrong or the machining is inaccurate.

Toyota MDT in MO

PS I think that Jeep also used color-coding on the back sides of the
bearing inserts to designate size.  IIRC they even allowed two
different color-coded insert halves to be installed in one journal if
the measurements called for it.  As stated above, this system was for
factory finished blocks and cranks only.
news - 19 Aug 2007 06:23 GMT
>> The book for the Jeep engine 'clearly' states the different 'oversizes'
>> are for the 'main' bearings, 'not' the crank to rod bearings.
[quoted text clipped - 28 lines]
> line bored/honed to get them back in alignment and back to the correct
> diameter.

I'm the OP, and I don't know if the replacement crank was turned or not.
 I didn't ask, and don't really care.  They just mentioned that they
had to line hone it to bring the bottom end back to square.  They didn't
tell me if it was .001 or .01 or .1 off - I didn't ask - I trust them to
machine it square for the race car, and that's all I need to worry about. :)

FWIW, I got my replacement timing set tonight, so I'll be doing that
tomorrow.

Ray
Steve W. - 19 Aug 2007 08:11 GMT
>> The book for the Jeep engine 'clearly' states the different 'oversizes'
>> are for the 'main' bearings, 'not' the crank to rod bearings.
[quoted text clipped - 85 lines]
> the measurements called for it.  As stated above, this system was for
> factory finished blocks and cranks only.

Yep there are a few engines that had the matched bearings. Most of them
were imports though. Suzuki, Mazda and Mitsubishi are the ones I can
remember up front. The reasoning went that it was faster and cheaper to
have the different bearings on hand to fit the journals than it was to
check the grind on every crank and regrind if it was out. Instead you
mic'd the journal and selected the correct combination to fit. .001-.005
under were the sizes on the Suzi., in .0005 increments IIRC.

Signature

Steve W.
Near Cooperstown, New York

Mike Romain - 21 Aug 2007 18:28 GMT
>> The book for the Jeep engine 'clearly' states the different 'oversizes'
>> are for the 'main' bearings, 'not' the crank to rod bearings.
[quoted text clipped - 85 lines]
> the measurements called for it.  As stated above, this system was for
> factory finished blocks and cranks only.

Geese guys.

It 'clearly' states the 'cylinder block' outer main journal diameter can
vary 0.010" and you buy stock bearings to fit.

These bearings come in sizes from 2.4901" up to an outer diameter of
2.5001".

It also states the stock 'crankshaft' main journal diameter is 2.2988"

This gives a whole bunch of 'honing' or reaming room without having to
change or dick with the centerline seeing as even being out a hair is
bad news for most engines.

I can see where a bad one might need the centerline changed by cutting
the journal, but...

Mike
ray - 18 Aug 2007 21:43 GMT
> Also true. GM specs allows a centerline difference of +/-.004 from the
> factory. However you still try to minimize the loss. On a couple
> Chrysler engines the allowance is only .001.

fwiw, and this is probably why they had to line hone my block, is when I
ran out of oil, the crank bent .060.  I now have a new crank, still cast
due to $$$, but I don't know if a forged one would have done any better
without any lubrication.  <sigh>

Racing is a good way to accumulate a large collection of blown up parts.
Blocks with air conditioning holes, tires that consist of one sidewall,
wheels that look like pretzels, hubless axles, 4 piece camshafts...

Ray
Steve W. - 19 Aug 2007 07:58 GMT
>> Also true. GM specs allows a centerline difference of +/-.004 from the
>> factory. However you still try to minimize the loss. On a couple
[quoted text clipped - 10 lines]
>
> Ray

Want some more? I went round-N-round for 8 years at various dirt tracks
before I decided I had enough..
Still have my picture of my entrance into the "river club" at Fonda...

Forged would likely have done the same. I ran a 358 one year that
decided to drop the oil pump drive in turn one, made it through 2 and
went to turn onto pit lane and she locked up TIGHT. Pulled the pan and
found the crank had snapped and took #2 main with it, snapped the
webbing. OOPS!

Signature

Steve W.
Near Cooperstown, New York

Steve - 20 Aug 2007 17:04 GMT
>>>> The engine is a small block Chevy, for my dirt track Camaro.
>>>> Last season I ran it out of oil (pan damage) and the machine shop
[quoted text clipped - 32 lines]
> takes material off 'both' the cap and block side of the hole.  The
> center line isn't affected.

You're talking about turning a JOURNAL on a crank, which affects the
inside diameter of the bearing that rides on that journal (and accounts
for the need for undersize bearings). Line boring affects the block
which determines the OUTSIDE diameter of the bearing shells, and there
are NO over/under sizes for that. You come back to the exact same
diameter, no other options exist.
Mike Romain - 21 Aug 2007 18:47 GMT
>>>>> The engine is a small block Chevy, for my dirt track Camaro.
>>>>> Last season I ran it out of oil (pan damage) and the machine shop
[quoted text clipped - 39 lines]
> are NO over/under sizes for that. You come back to the exact same
> diameter, no other options exist.

Not on a Jeep engine.

It 'clearly' states the 'cylinder block' outer main journal diameter can
vary 0.010" and you buy stock bearings to fit.

These bearings come in sizes from 2.4901" up to an outer diameter of
2.5001".

It also states the stock 'crankshaft' main journal diameter is 2.2988".

I can see where a shoddy shop might get the center off or there might be
too much damage, but that isn't what I was going on about.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's - Gone to the rust pile...
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Steve - 21 Aug 2007 20:34 GMT
> Not on a Jeep engine.

OK, then on virtually every other mass-produced engine out there....

> It 'clearly' states the 'cylinder block' outer main journal diameter can
> vary 0.010" and you buy stock bearings to fit.

Granted I've never built a Jeep inline 6, but I've NEVER heard of
bearing shells with different outside diameters. Ever. Doesn't mean that
they don't exist, but it means they're not the norm.

> These bearings come in sizes from 2.4901" up to an outer diameter of
> 2.5001".
>
> It also states the stock 'crankshaft' main journal diameter is 2.2988".

Screw the crankshaft journal, that's irrelevant to this discussion. The
journal passes through the middle of the bearing, we're talking about
the backside of the bearing shells. Talking about the journal just
confuses the issue.

> I can see where a shoddy shop might get the center off or there might be
> too much damage, but that isn't what I was going on about.

No, its the ONLY way to line-bore most engines. And it doesn't hurt a
thing! You gotta remember:

a) its ONLY done in a way that removes block material when absolutely
necessary (eg, bearing saddle damage due to a spun bearing, block
warpage due to overheating, etc.). It is also done whenever you
areinstalling new main caps, but in that case the boring bar just
"kisses" the block material and doesn't remove any material from the
block at all, it JUST cuts the caps to match the half-circle formed by
the block.

b) If you have to move the crank more than a few thousandths, the block
is junk. Line boring NEVER moves the crank enough to affect anything but
the timing chain tightness.
ray - 22 Aug 2007 08:26 GMT
> b) If you have to move the crank more than a few thousandths, the block
> is junk. Line boring NEVER moves the crank enough to affect anything but
> the timing chain tightness.

fwiw, my replacement chain is nice and tight, I only got an align hone,
so I don't know how much they took off, but it couldn't have been much.

Comp Cams sells timing sets for align bored blocks.

Ray
Thomas Tornblom - 20 Aug 2007 20:53 GMT
I have a really nice Australian Rollmaster timing chain in my 351
Cleveland, and on the box it came in they state "line bored sets
available", which I assume is for this precise reason.

This link also state that:
http://www.holleycarbs.com.au/productRollmaster.htm
aarcuda69062 - 21 Aug 2007 01:38 GMT
> I have a really nice Australian Rollmaster timing chain in my 351
> Cleveland, and on the box it came in they state "line bored sets
> available", which I assume is for this precise reason.
>
> This link also state that:
> http://www.holleycarbs.com.au/productRollmaster.htm

Yup, I have a Rollmaster in my 340.  When I ordered it, I had to
give them the center to center distance between the cam and the
crankshaft.  Nice tight fit!
news - 21 Aug 2007 06:28 GMT
>> I have a really nice Australian Rollmaster timing chain in my 351
>> Cleveland, and on the box it came in they state "line bored sets
[quoted text clipped - 6 lines]
> give them the center to center distance between the cam and the
> crankshaft.  Nice tight fit!

fwiw, my timing set was just stretched - I replaced it and it's nice and
tight.  Now, about the bent rocker stud... <sigh>  Race Cars... It's
like crack, only more expensive.

Ray
Steve W. - 21 Aug 2007 17:42 GMT
>>> I have a really nice Australian Rollmaster timing chain in my 351
>>> Cleveland, and on the box it came in they state "line bored sets
[quoted text clipped - 12 lines]
>
> Ray

Fun ain't it.
What track do you run at?

Signature

Steve W.

ray - 21 Aug 2007 19:08 GMT
>>>> I have a really nice Australian Rollmaster timing chain in my 351
>>>> Cleveland, and on the box it came in they state "line bored sets
[quoted text clipped - 15 lines]
> Fun ain't it.
> What track do you run at?

Red River Co-Op Speedway up in Winnipeg, Manitoba.
The Camaro is what used to be called Enduros, but now is the "Stock Car
Challenge" - 200 laps around a 4/10 mile oval.
In 4 years, I think I've managed to bust everything on the car at least
once.
When I'm not crying over my Visa statement, it's fun.  My buddy was over
last night and we replaced a smushed in control arm and a lower balljoint...

Ray
 
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