Interesting question for one of you technicians

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Old 18 Mar 2005, 01:37 am   #1 (permalink)
Ken Day
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Default Interesting question for one of you technicians

I'm rebuilding my 4 cylinder 5 SFE. Before I tore it down I marked the
top of the pistons ....while the engine was still in the car just
after removing the head.
I was putting the short block back together earlier tonight and
noticed on the bottom of the rod caps there is a number. However ,
these numbers go in reverse order as if numbering from the rear of the
engine forward.
I wouldn't think these numbers should be in reverse order but maybe
they are there for some reason I'm not aware of.
These numbers are CAST into the bearing cap so no one put them
there.
I'm wondering if someone else had it down before me and put the
pistons in reverse order. Since there is no noticable wear in the
cylinders....about 100,000 miles on it , and I did mic the bores , I
don't suppose it would hurt to put the pistions in the wrong hole. I'm
a;ways very careful about marking and putting back together the same
way the parts came out. Did I possibly have my head up my rear and
numbered the tops of the pistons wrong. DOn't think so , but I suppose
it is possible. But , it is kinda hard to mark them backwards with the
engine in the car.

I suppose the bottom line is, does it really matter if they are put in
reverse order ?

Thanks in advance

kd
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Old 18 Mar 2005, 08:42 am   #2 (permalink)
Daniel
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Default Re: Interesting question for one of you technicians

Consulting the Factory service manual, the _main_ bearing caps are
numbered for order, and both main and rod bearing caps are numbered 1,
2 or 3 for bearing size, but the instruction for pistons, rods and rod
caps are only "keep in the same order" as removed.
Unless there is some compelling evidence - such as the reason for the
rebuild - immediately after a botched prior attempt, the general advice
is to always put the pistons back in the same order. Obviously you know
this since you marked them.
My guess is you would be creating more problems by changing the order.
There is no factory guidance as to cast in numbers on the rod caps, but
there are numbers on the main bearing caps shown.

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Old 18 Mar 2005, 02:35 pm   #3 (permalink)
Jason James
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Default Re: Interesting question for one of you technicians


"Ken Day" <kd1942@aol.com> wrote in message
news:rf0l31lv5b4bg9nshbnsl8rmk1mntg87j1@4ax.com...
> I'm rebuilding my 4 cylinder 5 SFE. Before I tore it down I marked the
> top of the pistons ....while the engine was still in the car just
> after removing the head.
> I was putting the short block back together earlier tonight and
> noticed on the bottom of the rod caps there is a number. However ,
> these numbers go in reverse order as if numbering from the rear of the
> engine forward.
> I wouldn't think these numbers should be in reverse order but maybe
> they are there for some reason I'm not aware of.
> These numbers are CAST into the bearing cap so no one put them
> there.
> I'm wondering if someone else had it down before me and put the
> pistons in reverse order. Since there is no noticable wear in the
> cylinders....about 100,000 miles on it , and I did mic the bores , I
> don't suppose it would hurt to put the pistions in the wrong hole. I'm
> a;ways very careful about marking and putting back together the same
> way the parts came out. Did I possibly have my head up my rear and
> numbered the tops of the pistons wrong. DOn't think so , but I suppose
> it is possible. But , it is kinda hard to mark them backwards with the
> engine in the car.
>
> I suppose the bottom line is, does it really matter if they are put in
> reverse order ?
>
> Thanks in advance


Daniel is right,..those numbers do not indicate which piston goes in which
hole,..they are grading numbers (1,2,3) to give the best clearance fit for
each rod-bearing (installed) to its respective crank journal. The reason
they do this is, is to allow for slight machining differences (diameter)
between each crank bigend journal. The difference between the 3 numbers is
probably in the area of 0.5 thou/inch or so.
You need to install the pistons with their correct rod-bearing caps in the
order you removed them.


Jason


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Old 19 Mar 2005, 03:06 am   #4 (permalink)
Ken Day
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Default Re: Interesting question for one of you technicians

On Sat, 19 Mar 2005 07:35:49 +1100, "Jason James"
<vellicet@bigpond.com> wrote:

>
>"Ken Day" <kd1942@aol.com> wrote in message
>news:rf0l31lv5b4bg9nshbnsl8rmk1mntg87j1@4ax.com.. .
>> I'm rebuilding my 4 cylinder 5 SFE. Before I tore it down I marked the
>> top of the pistons ....while the engine was still in the car just
>> after removing the head.
>> I was putting the short block back together earlier tonight and
>> noticed on the bottom of the rod caps there is a number. However ,
>> these numbers go in reverse order as if numbering from the rear of the
>> engine forward.
>> I wouldn't think these numbers should be in reverse order but maybe
>> they are there for some reason I'm not aware of.
>> These numbers are CAST into the bearing cap so no one put them
>> there.
>> I'm wondering if someone else had it down before me and put the
>> pistons in reverse order. Since there is no noticable wear in the
>> cylinders....about 100,000 miles on it , and I did mic the bores , I
>> don't suppose it would hurt to put the pistions in the wrong hole. I'm
>> a;ways very careful about marking and putting back together the same
>> way the parts came out. Did I possibly have my head up my rear and
>> numbered the tops of the pistons wrong. DOn't think so , but I suppose
>> it is possible. But , it is kinda hard to mark them backwards with the
>> engine in the car.
>>
>> I suppose the bottom line is, does it really matter if they are put in
>> reverse order ?
>>
>> Thanks in advance

>
>Daniel is right,..those numbers do not indicate which piston goes in which
>hole,..they are grading numbers (1,2,3) to give the best clearance fit for
>each rod-bearing (installed) to its respective crank journal. The reason
>they do this is, is to allow for slight machining differences (diameter)
>between each crank bigend journal. The difference between the 3 numbers is
>probably in the area of 0.5 thou/inch or so.
>You need to install the pistons with their correct rod-bearing caps in the
>order you removed them.
>
>
>Jason
>

I'm aware of the numbering for both the rod and main bearings. Honda
also uses a numbering/color mark to indicate the bearing to get the
best oil clearance. I've rebuilt a number of Honda engines but not
many Toyotas. I don't know if they still use the same system , but
older Hondas used a color for the rod bore clearance and a number for
the crank clearance.
I have run into so many numbers on this engine and I'm wondering what
they are all for.

There is a number and a letter on the con rod and cap on one side ,
this number refers to the bearing size .Don't know what the letter
stands for.
The other side has a number that crosses the gap between the rod and
cap....(half the number on the cap , half on the rod).All the numbers
and letters have been stamped with a hand held die.
Again , the numbers I'm in question about are cast into place on the
bottom of the rod caps. These are numbered 1-4 .
The local Toyota dealer couldn't tell me what they mean ???

Incidentally , I had checked for proper oil clearance and that was OK.

Thanks a bunch for your help guys.
Much appreciated.

Ken Day
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Old 19 Mar 2005, 08:19 am   #5 (permalink)
Daniel
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Default Re: Interesting question for one of you technicians

http://autos.groups.yahoo.com/group/Toyotas_Only/

This question should be posted at the Yahoo group.
You need to join, but there is no charge.
Peopled by a couple of master technicians with many years of
experience.
Learned some invaluable tips there for replacing the timing belt
(remove crank pulley before engine support brace to improve access to
bolts), and tips on installing the oil pan sealer around the rear main
bearing (go very close to the edge of the pan to avoid leaks).
That's the kind of advice you're looking for.

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Old 19 Mar 2005, 01:22 pm   #6 (permalink)
Jason James
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Default Re: Interesting question for one of you technicians


"Ken Day" <kd1942@aol.com> wrote in message
news:1epn311hrd7ie78re2c1m544kulqtrlf2r@4ax.com...
> On Sat, 19 Mar 2005 07:35:49 +1100, "Jason James"
> <vellicet@bigpond.com> wrote:
> >

> I'm aware of the numbering for both the rod and main bearings. Honda
> also uses a numbering/color mark to indicate the bearing to get the
> best oil clearance. I've rebuilt a number of Honda engines but not
> many Toyotas. I don't know if they still use the same system , but
> older Hondas used a color for the rod bore clearance and a number for
> the crank clearance.
> I have run into so many numbers on this engine and I'm wondering what
> they are all for.
>
> There is a number and a letter on the con rod and cap on one side ,
> this number refers to the bearing size .Don't know what the letter
> stands for.
> The other side has a number that crosses the gap between the rod and
> cap....(half the number on the cap , half on the rod).All the numbers
> and letters have been stamped with a hand held die.
> Again , the numbers I'm in question about are cast into place on the
> bottom of the rod caps. These are numbered 1-4 .
> The local Toyota dealer couldn't tell me what they mean ???
>
> Incidentally , I had checked for proper oil clearance and that was OK.
>
> Thanks a bunch for your help guys.
> Much appreciated.
>
> Ken Day


Have you lost the order you pulled the pistons out? If not and the engine
had good oil-pressure prior, you dont have a problem.

Compared to older generation engines, modern engines are built to more
exacting standards,..but things like keeping the beasring caps mated to its
conrod has always been needed.

As modern engines are assembled, each parameter eg bore size and piston
grade (another term for piston diameter) are individually matched. The same
probably applies to conrod length (as measured between the gudgeon and
bearing centre) and piston height ( as measured between the crown and
gudgeon centre) to achieve as even a compression ratio for all cylinders.
Then we have the issue of individual weight of each piston vs conrod,...and
so it goes on... that is what all those codes are for,..to allow the final
assembly to be near as perfect as possible. As backyard rebuilders, all we
can do is not mix anything up and try to not install and remove things like
main bearing caps too often, as they are line-bore checked at the factory
and unecessary removal only serves to lose that perfect bore. .There are
also other considerations, over time and use, like block distortion, which
will cause a loss of line-bore anyway


In other words, there is no such thing as a machine which will, at a
reasonable cost, turn-out identical machined parmeters at the end of a run
compared to the start,..hence all those codes.

When it comes to bearing shells however, they would all be one size from the
bearing manufacturer. Other wise, when it came to buying new sets from your
local auto-shop, thered be too many fractional sizes. eg std, std + 1 thou
and so on. Instead they usually just have the std oversizes of 10 thou
increments.

There's an old saying: there's nothing quite as quiet as a new
engine",.....(unless you are prepared to blue-print the old one.)

Jason








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Old 19 Mar 2005, 02:57 pm   #7 (permalink)
Ken Day
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Default Re: Interesting question for one of you technicians

On Sun, 20 Mar 2005 06:22:28 +1100, "Jason James"
<vellicet@bigpond.com> wrote:

>Have you lost the order you pulled the pistons out? If not and the engine
>had good oil-pressure prior, you dont have a problem.


No. I marked the pistons before I pulled them out. Maybe I didn't
clearly explain what I was wondering about , the numbers that are cast
into the bottom of the rod caps. Since they are numbered in reverse
order and IF these numbers do represent which cylinder they belong in
, then someone has had the engine down before and put it back together
in reverse order. But , these type numbers are always ( at least on
engines I have torn down) been stamped by hand. I'm really curious as
to what these numbers mean. The engine is going back the same way it
was when I tore it down. I'm just curious .

>Compared to older generation engines, modern engines are built to more
>exacting standards,..but things like keeping the beasring caps mated to its
>conrod has always been needed.
>In other words, there is no such thing as a machine which will, at a
>reasonable cost, turn-out identical machined parmeters at the end of a run
>compared to the start,..hence all those codes.


I agree.

>When it comes to bearing shells however, they would all be one size from the
>bearing manufacturer. Other wise, when it came to buying new sets from your
>local auto-shop, thered be too many fractional sizes. eg std, std + 1 thou
>and so on. Instead they usually just have the std oversizes of 10 thou
>increments.


But the bearings are not all one size. Thats the reason for the codes.
There is approx .006 mm or .00025 inch difference in thickness from
one size (number) to the next to assure best possible fit . Both rod
and main bearings are numbered.
You can , however , buy aftermarket bearings that are all one size.
They more or less strike a happy medium , but you will in most all
cases have varying oil clearances , though usually within acceptable
limits.

>There's an old saying: there's nothing quite as quiet as a new
>engine",.....(unless you are prepared to blue-print the old one.)

I agree.

>Jason


Thanks for your input. I appreciate it.

Ken Day
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Old 20 Mar 2005, 11:46 am   #8 (permalink)
Jason James
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Default Re: Interesting question for one of you technicians


"Ken Day" <kd1942@aol.com> wrote in message
news:v33p31tqkc4c14lj54hn7mp3h5b1v0802c@4ax.com...
> On Sun, 20 Mar 2005 06:22:28 +1100, "Jason James"
> <vellicet@bigpond.com> wrote:
>
> >Have you lost the order you pulled the pistons out? If not and the engine
> >had good oil-pressure prior, you dont have a problem.

>
> No. I marked the pistons before I pulled them out. Maybe I didn't
> clearly explain what I was wondering about , the numbers that are cast
> into the bottom of the rod caps. Since they are numbered in reverse
> order and IF these numbers do represent which cylinder they belong in
> , then someone has had the engine down before and put it back together
> in reverse order. But , these type numbers are always ( at least on
> engines I have torn down) been stamped by hand. I'm really curious as
> to what these numbers mean. The engine is going back the same way it
> was when I tore it down. I'm just curious .
>
> >Compared to older generation engines, modern engines are built to more
> >exacting standards,..but things like keeping the beasring caps mated to

its
> >conrod has always been needed.
> >In other words, there is no such thing as a machine which will, at a
> >reasonable cost, turn-out identical machined parmeters at the end of a

run
> >compared to the start,..hence all those codes.

>
> I agree.
>
> >When it comes to bearing shells however, they would all be one size from

the
> >bearing manufacturer. Other wise, when it came to buying new sets from

your
> >local auto-shop, thered be too many fractional sizes. eg std, std + 1

thou
> >and so on. Instead they usually just have the std oversizes of 10 thou
> >increments.

>
> But the bearings are not all one size. Thats the reason for the codes.


I meant the crank-journals are not all the same size hence the selection of
conrod with the knowledge of how much the installed bearing shell will yield
in terms of rodbearing size.

If they have a crank-journal which is std + 0.5 thou", it is by far the
cheapest solution to select a piston-rod assemble which will provide the
calculated clearance for that journal. The variation-parameter in the rods
which provide this range of selection, would be the rod's bearing
circle,..which in this example, would be - 0.5thou". The shells would be a
constant in that they are all the same and these *required* slight
differences in size would be accomodated by their crush.

In other words: if you have 2 rods, one is std +0.5 thou, the other std -
0.5 thou,..you can still maintain that difference (for fitting to an
individual c/shafts which needs them) even tho you are using the same size
sets of bearing shells. The thing which will be different tho, is the
bearing crush, but not so different to create a problem for the *installed*
bearing.

That is my knowledge on the subject which I haven't really read
anywhere,..it's an amalgamation of mechanic talk mostly....can anyone
confirm or deny this?



> There is approx .006 mm or .00025 inch difference in thickness from
> one size (number) to the next to assure best possible fit . Both rod
> and main bearings are numbered.


Do you mean the bearing shells are numbered so, or the caps?


> You can , however , buy aftermarket bearings that are all one size.
> They more or less strike a happy medium , but you will in most all
> cases have varying oil clearances , though usually within acceptable
> limits.


Only if your rod has gone oval, which can happen in severe service, and or
over-rev situations.

Jason






> >There's an old saying: there's nothing quite as quiet as a new
> >engine",.....(unless you are prepared to blue-print the old one.)

> I agree.
>
> >Jason

>
> Thanks for your input. I appreciate it.
>
> Ken Day



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Old 20 Mar 2005, 12:54 pm   #9 (permalink)
Philip
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Default Re: Interesting question for one of you technicians

Jason James wrote:
> I meant the crank-journals are not all the same size hence the
> selection of conrod with the knowledge of how much the installed
> bearing shell will yield in terms of rodbearing size.
>
> If they have a crank-journal which is std + 0.5 thou", it is by far
> the cheapest solution to select a piston-rod assemble which will
> provide the calculated clearance for that journal. The
> variation-parameter in the rods which provide this range of
> selection, would be the rod's bearing circle,..which in this example,
> would be - 0.5thou". The shells would be a constant in that they are
> all the same and these *required* slight differences in size would be
> accomodated by their crush.
>
> In other words: if you have 2 rods, one is std +0.5 thou, the other
> std -0.5 thou,..you can still maintain that difference (for fitting to an
> individual c/shafts which needs them) even tho you are using the same
> size sets of bearing shells. The thing which will be different tho,
> is the bearing crush, but not so different to create a problem for
> the *installed* bearing.
>


FIRST. NEVER in technical discussion use such lame shorthand as "0.5thou."
The correct expression is 0.005" . Now, for the two journals you listed
above, you could use the same bearing shell for your journal IF the journals
were five TEN thousandths difference (0.0005"). Bearing shells typically
come in STD, 0.002", 0.003, 0.005, 0.010, 0.020, and 0.030" undersize.
Remember, as a journal wears or is turned-down, it gets smaller. Typical oil
clearance on a journal can be 0.00075 to 0.00175".

What did I miss? ;-)
--

- Philip



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Old 20 Mar 2005, 01:58 pm   #10 (permalink)
Jason James
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Default Re: Interesting question for one of you technicians


"Philip" <1chip-state1@earthlink.n0t> wrote in message
news:lFj%d.16288$qf2.318@newsread2.news.atl.earthl ink.net...
> Jason James wrote:
> > I meant the crank-journals are not all the same size hence the
> > selection of conrod with the knowledge of how much the installed
> > bearing shell will yield in terms of rodbearing size.
> >
> > If they have a crank-journal which is std + 0.5 thou", it is by far
> > the cheapest solution to select a piston-rod assemble which will
> > provide the calculated clearance for that journal. The
> > variation-parameter in the rods which provide this range of
> > selection, would be the rod's bearing circle,..which in this example,
> > would be - 0.5thou". The shells would be a constant in that they are
> > all the same and these *required* slight differences in size would be
> > accomodated by their crush.
> >
> > In other words: if you have 2 rods, one is std +0.5 thou, the other
> > std -0.5 thou,..you can still maintain that difference (for fitting to

an
> > individual c/shafts which needs them) even tho you are using the same
> > size sets of bearing shells. The thing which will be different tho,
> > is the bearing crush, but not so different to create a problem for
> > the *installed* bearing.
> >

>
> FIRST. NEVER in technical discussion use such lame shorthand as

"0.5thou."
> The correct expression is 0.005" .


"0.005" is 5 thousandths of an inch. I was using my 'lame' notation to
indicate 0.0005" (1/2 of one thou" or 0.5 thou)

I assume you meant to write 0.0005"?


Now, for the two journals you listed
> above, you could use the same bearing shell for your journal IF the

journals
> were five TEN thousandths difference (0.0005").


I was asking, is it the case that hand-selected conrods which had
bearing-circles (correct name here plse Phil?) matched to the differing
crank-journals could use the same shells with the result the correct
oil-clearance ( eg 0.00075") was maintained for those two journals?


Bearing shells typically
> come in STD, 0.002", 0.003, 0.005, 0.010, 0.020, and 0.030" undersize.


Is that the case from a retailer? I thought the std range was in 0.010"
increments.



> Remember, as a journal wears or is turned-down, it gets smaller. Typical

oil
> clearance on a journal can be 0.00075 to 0.00175".


OK,..tho that upper limit seems large for a modern engine.

Jason


> What did I miss? ;-)
> --
>
> - Philip



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