Parent bores are not round

[chhanes]

I am at the engine rebuilding stage of rescuing the Farmall M on which I grew up. Had the engine put thru a hot tank but it has sat for months while I tended to other things. I ran a light hone thru each cylinder to remove the hot tank residue as well as some surface rust. My (thin wall) replacement sleeves are pretty close to 4.125 plus a few tenths. I ran the bore gage thru each cylinder and found the parent bores to be egg shaped. Specifically, cylinder-to-cylinder direction they are ~ 4.125.
However, in the direction across the engine they are all .002 over size. I assume the sleeves, when installed, will take this same shape. Is this acceptable for a tractor that will see light tillage at most?

 

[fastfarmall]

Not sure what to say, but i did have a 327 Chevy truck engine,4 bolt main, that was out of round cylinders, it used oil all the time,i just lived with it, but it had good power!

 

[the tractor vet]

would i stuff those new sleeves in , NOPE Fist off they have to fit correctly . What i would do is have the block bored and a thin wall repair sleeve pressed in and bored for proper fit . The new sleeves are thin to start with and forcing them down a egg shaped hole just may crack them .
Do it right the first time and be done with it .

 

[Fritz Maurer]

If you do some research you might find a source for
specific engine dimensions... lot of engines have a
spec for ,, maximum cylinder out-of round,, and
then you would know for sure if it is ok to assemble
it as-is.

 

[rustred]

I would have at least oiled them sleeve bores and not left
them sitting for months rusting away. But ya as vet said if
they are out of round no sense installing sleeves till the
bore is correct. How much out of round ??

 

[Smarten_up]

Metal does have elasticity, 2 thousands at the very bottom end where the piston doesn't even travel seems fairly insignificant considering the proposed light duty application and the length of the sleeves. But then I'm not a high performance engine specialist. Wouldn't the 'O' ring at the base also compensate to some extent assuming the sleeves are round?

 

[rustred]

No o rings. Dry sleeves

 

[Janicholson]

The Tractor Vet is correct. even straight honing the native bores will only make them loose. Jim

 

[rustred]

well yes thats a for sure. you cant hone parent bores, i know that also.

 

[chhanes]

Blue Ribbon Service Training manual notes that rings can be replaced with satisfactory results if the out of round does not excede .0037. So there is the rub. I did not want to suffer the wait to get the engine bored and repair sleeves installed. Just wanted you guys to weigh in. I would be inclined to get them round again but they were obviously out of round from the factory and this tractor ran like a top for the 18 years we had it.

 

[Fritz Maurer]

Unofficially, without looking anything up, .002
doesnt sound like very much... thats only .001 per
side.

 

[caterpillar guy]

Vet is right you want the bores to be round. So pony up the piggy bank and bore them round and push a thin sleeve in to fit the sleeves. IF you do this take the sleeves in with the block as they will want them so they can fit them to the insert they will make for them. In the long run you will thank us for doing it this way.

 

[Smarten_up]

Yeah, I shouldn't have commented on an engine I don't know. I thought they were wet sleeve.

 

[used red MN]

Here is my opinion and I will probably be called hack.
You asked ..Is this acceptable for a tractor that will see
light tillage at most?.. You say they are out of round by
0.002. You say the book gives a max spec of 0.0037.
The book was written per engineers that provided
tolerances to be acceptable for fully loading the
engine. So by that you should be able to put it together
with no worries. I suspect 1000s of those engines were
re-sleeved over the years by individuals that did not
even have a micrometer let alone a snap gauge. I also
bet a bunch of those parent bores were out of round
and the sleeves just got shoved in. I would also bet the
majority of them lasted just fine. Just do not expect it
to pull like those the TV did because he did it ..right.. ;
> ) This is a 1850 rpm engine, it comes nowhere close
to producing 1 hp per cubic inch. That is almost what a
GM 5.3L LS engine makes at 3-4000 rpm. Being more
..critical.. of how well the combustion gases are being
sealed into the cylinder to make power in that engine is
far more important than it is to this old tractor engine.
On the other side of the coin there is also the fact that
there is only one way to do it and say you did it right.

 

[chhanes]

Used RED: Thanks for that thoughtful and thorough reply. You capture my feelings exactly. I don't really think .001 per side should wreck a tractor engine, but I know it is better to have it as round as possible. Taking this detour really wrecks my schedule as I am 2600 miles away from the tractor and managing another outsource operation from here is not that easy or efficient. I probably will try to get the engine bored and fitted with repair sleeves but i just wondered if all of you guys were going to say I was worried about nothing. Thanks again.

 

[560Dennis]

Understand your not there ,but need to measure
You spent extra for higher compression pistons for some reason ,light tillage , why not measure and correct if necessary for maximum output
Did you measure the sleeves. Are they round ? Measurements at three depth , wall thickness also three depth
Also outside diameter of pistons the stack of assembled tolerances of maximum and minimum material conditions could exceed the 0037 ,
how will you know unless you measure .
Or ignore your choice

 

[BarnyardEngineering]

(quoted from post at 22:57:13 06/06/23) Just do not expect it
to pull like those the TV did because he did it ..right..

I pretty much agree with everything you said except to note that in this statement I believe you are splitting hairs. If being .002 out of round on this level of technology makes more than a fraction of a HP difference and shortens the life of the engine by more than a few minutes, I would be surprised.

As you said, 1000's, probably 100's of 1000's, of these engines have had sleeves shoved in without even measuring the parent bore.

Some days I wonder if some of these guys are colluding to make business for the machine shops. Yes machine shops need to stay in business but sheesh, most of us aren't made of money, and sometimes good enough is good enough.

 

[the tractor vet]

Well you do what you want . When i do one it has to be right as i am working on your dime and if something i do does not work and it comes back now it is on my dime . When you going for a play engine or and all out performance engine it really does not matter . Ya want it right the first time . Me i want to know the hole dia. of each hole down to the tenths and out of roundness . I want to write that down each hole Then check each sleeve and write that down and same goes for each new piston . Find the big one and the small one and mark the size on each same with the block ya mark the size of the hole at each hole and ya find the sleeve that will fit the best in that hole . Ya can't fill a hole that is to big with a sleeve that is to small. Yes there are factory tolerances . it's nice to find a half way point to work with . Factory boring of the blocks was not that great and on some I H engines they were really bad an they had to make two sizes of sleeves to over come this and stamped the block at each hole with a A -B or a C-D bore class and before you bought and engine kit ya had to know what sleeves ya needed . on yours depending on the SLEEVE and how the org Bore mic's out if you go to FITTING the sleeves then mic'ing each piston and finding the The big one and the small one then fit each to the hole ya may be able to take out that .002 out of roundness with a ridgid hone to get your skirt to wall clearance . Then if ya want to make it BETTER one can get into making the connection rods all weight the same and also the pistons by making the heavy one weigh the same as the lightest . and we can go even down the rabbit hole even deeper with the C Cing of the head then have the cam freshed up to factory spec's on all lobes . reface the rocker arms add .020 shims to the valve springs . Yea i can get carried away on and engine build something i have been doing now for over 60 years . So why not make it better then factory when you have them down , as there had to be a reason for this rebuild . What you learn with each is that Blocks and head do not stay perfect , crank shafts ware , cams ware lifters ware . I'll bet your main bearing saddles are NOT perfect nor is the deck of your block and the counter bores are not dead on just one more tiny tid bit that needs checked so that the sleeves set as they should . There use to be three of us on here that made our living on fixen I H STUFF now i have not seen Pete or Owen on for a good while and have no idea if they are still kicking or not . I came real close four years ago of checking out . Yes i am vary OCD on my work .

 

[chhanes]

Did you measure the sleeves. Are they round ? Measurements at three depth , wall thickness also three depth
Also outside diameter of pistons the stack of assembled tolerances of maximum and minimum material conditions could exceed the 0037 ,
how will you know unless you measure .
Or ignore your choice

If you check out the pictures, it might indicate that I Know full well how to measure. I can include the charting, if that woulld make you feel better. I spent half of my career measuring down to millionths, so relax.[/quote]Sorry, but this one just rubbed me the wrong way.

This post was edited by chhanes on 06/07/2023 at 03:08 pm.

 

[rustred]

when i saw this picture i was wondering if you just went out and bought these precision measuring tools, cause it looks like they were never
used yet. and now you say you spent half your career measuring to the millionth. i have never saw tools look like that by any machinest. even
the tools in mechanic's classes are not that clean that the instructors use.