8n connecting rod side clearance

I started putting together the bottom end of my 8n engine today. I got the crankshaft and piston, rods installed and torqued to spec. Then I noticed it had a lot of rod side play. It had 0.018 on one rod, 0.011 on 2 rods and about 0.007 on the fourth. I had the crank turned 0.040 for the rod journals. new liners put in and the rods sized at the local machine shop. My question is is 0.018 too much movement on the rods. I know the spec is 0.004 to 0.011 movement, but sometimes other things still work. I may call the machine shop tomorrow to see if something can be done to correct it or should I just let it run. Any one else run into excessive side play? And what was done to fix it if anything?
 

When I did my rebuild on my 51 I had excessive side to side play on the rods. So I personally would be concerned. I had the machine shop recondition the rods and install new bushings. Of course my engine had never had a rebuild and the crank was turned 0.010 on either the mains or rods and .020 on the other...I forget which one was which.. I think the rod journals was .020. We platiguaged and checked every clearance possible and everything was well within specs. Me personally would fix it before running it after spending a grand on machine work and the kit.
 
I can't help thinking that such a discrepancy in rod journal side play may be attributable to faulty setting up of the crankshaft grinder.

I remember the old machinist friends of mine telling me how much they were going to miss their old crankshaft grinder when the shop finally closed. They thought it was the best which made me think that they are far from being all the same.
 
(quoted from post at 02:42:44 10/03/14) I can't help thinking that such a discrepancy in rod journal side play may be attributable to faulty setting up of the crankshaft grinder.

I remember the old machinist friends of mine telling me how much they were going to miss their old crankshaft grinder when the shop finally closed. They thought it was the best which made me think that they are far from being all the same.

I'd have to say this is the first time I've used a machine shop and I was impressed. The owner can't be over his 40's and absolutely as tight as my engine fit together I almost can't wait to rebuild another. I'd like to know where he ordered the kit cause it was perfect. He checked line bore, new Welch plugs, new sleeves, ground the valves, decked the block and head..... I had to spend hrs grinding the head for the pistons to clear with a dremmel...new valve searts, new ring gear installed on the fly wheel, reconditioned the connecting rods, ground the crankshaft, rebuilt the oil pump. Well worth the 1000 and 120 mile round trio twice.... I just had to mess up the rope seals so the leak :) and the front of the engine leaks between the oil pan and engine...oops
 
I will call the machine shop tomorrow and see what they say about it. I would really like to have it fixed, at least be in the specs of the manual. They turned the crank and resized the rods, I thought they would have checked for the amount of clearance of the rods. I will post back what they say. I just hope I dont have to buy different rods or a new crank to fix it, I've spent a plenty on this engine already.
 

If its because of something they machined wrong I would insist they fix it...and if it was a reputable machine shop they would correct their wrong no ?'s asked. I know when we did mine all were the same specs...there was no difference between cylinders or connecting rods.... Almost seems like they did one or 2 and not the other 2. I hope that your platiguaging the bearings on assembly...its a pita but absolutely if theres a problem with the rods better check all you can...did you check the ring gap? Its my opinion to have that much of a clearance difference between 4 cylinders...you need a new machine shop
 

Right and any good machine shop would build it up and turn it back so it meets specs...whatever it had to be ground...that being said I think .040 is the max they recommend and correct me if im wrong they recommend on grinding. That being said..if all else fails and its a front mount I have a front mount I can pull apart for the crankshaft and rods...no guarantee they wont need work either. id have to mic the journals....
 
I agree with needing new machine shop. I did plasti gauge
bearings and all were ok, and I did check ring gap and it was also
good. So far the only thing wrong appears to be the rod side play,
but they had my engine for 3 months doing what they did to it,
basically turn crank, install new liners and valve job, rebuild oil
pump, resize rods and put pistons on rods. One thing that they did
surprised me, and I didnt know if it was a bad thing or not. When
they did the valve job, everything was replaced with new adjustable
tappets. The machine shop didnt have the correct tool to adjust
the valves, so they drilled a hole in each "boss" for the valve to go
through. The part I'm calling the "boss" is part of the block that
you see when you remove the 2 valve covers and see the valves in
the block. They drilled this hole so that the person adjusting the
valves could stick a small allen wrench through the hole in the
block into the new adjustable tappet so that the valve could be
adjusted. Is this normal practice? Ive never seen it done, but I am
also new to tractor engines.
 
Crank grinder in action.
https://www.youtube.com/watch?v=y0NjkT0mqg0

Hear the part where he says that it is now hitting the side of the crank journal? That's obviously the part relative to side clearance. The age and condition of the lathe and of the stone and of the operator . . . all important.

A machinist who kind of retired here on the island set up a machine shop at his place. His name was alex Carlisle and he was one of the machinists who worked on the Canada arm of the space vehicle. anyway, he told me one day to beware of old brake disk and drum grinders because often times a disk would be .007 out of plane because of the condition of the grinders' bearings.

So from then on I took rotors to him and he turned them on his big lathe.
 
Thanks, that was nice video of turning a crankshaft, whoever
turned mine, may have not payed attention and took off too much.
I dont think that it had any excess movement when i took it apart.
But it does now.
 

And I wouldn't waste any money doing a machine shop number on the rods because that won't make your "big ends" any wider.

It's good that you know your initial clearances . . . makes it harder for them to assert that the excessive clearance existed when they received the shaft.
 
Then what should I do? Should I continue putting it together and
run it with the extra movement? Would it hurt anything or shorten
the life of the engine?
 
Not sure what to suggest and don't want to worry you to death needlessly.
The other N flathead rebuilders on this forum will no doubt have some sagely advice for you tomorrow.

All I can say is that when allowable factory tolerances are exceeded, the wear factor becomes increasingly more rapid . . . and you say you have .018 where .011 is the allowable max.
for me, I'd want to ensure that money already spent wasn't "good money after bad" as they say and so I'd do whatever necessary
for a rebuild you can be totally confident about -- that you know will last many hard working years.

It would be interesting to know the extent to which excessive side play will affect oil pressure.

New thrust bearing on your main journal will stabilize crankshaft end play and with perfect tolerances on the rod bearings, perhaps the rod travel will stick to the plane of rotation determined by the break in mating of the parts. (?)

That being the case, one could put a new thrust bearing on that main journal some years later to ensure minimum end play.
 
Thanks for the reply, I think I will talk to the machine shop
tomorrow, but I doubt that they will be much help. I bet I end up
having to get new rods or crankshaft. I've spent so much already
that I would hate to run it as is and it self destruct early. If I end
up getting different crank or rods its back to the machine shop
and spend even more money with them and waiting a couple
months to get it back again. But I would like it to be within spec or
at least within a few thousandths.
 

Is the width of each rod exactly the same?
Is each rod on exactly the same journal it came off of?
 
Each rod is on the exact journal it came off of. I checked and
rechecked that many times. However I haven't measured the width
of each rod, that is something I probably need to do tomorrow.
Would be nice if I could just replace one rod. I know its hard to see
a few thousandths wear on a rod end, but I did examine them
closely when putting them in and none looked like it had any wear
on the sides. But i do need to remove at least the loosest two and
measure them tomorrow.
 
Not basing this on any official "specs" but on experience... you will be FINE.

Oil clearance between the rod inserts and the journal is CRITICAL, but the rod end play, not so much.
 
(quoted from post at 07:31:40 10/03/14) When Bob post stand up and pay attention... Move on with your build...
greed! You just got up earlier than me, Hobo!
 
Thanks for the information. I just called the machine shop and they said the same thing. They said they put them together all the time and see this very often. They said it will not cause any problem ay all.
 
Keep it below 5,000 rpm and it will be OK ;)

This site sells .040 mains and .060 rod bearings . Ebay has a set of .060 mains for sale now .

Technically the weak spot on a crank shaft is where the journal meets the counter weight , a ground crank can be stronger than stock if the radius is built up by not machined as tight as the original radius .

On these tractors you would not have to worry about running a 60/60 crank .
 
(quoted from post at 06:08:00 10/03/14)
(quoted from post at 07:31:40 10/03/14) When Bob post stand up and pay attention... Move on with your build...
greed! You just got up earlier than me, Hobo!

LOL, That's why this site is the best. Been quietly following the thread, not considering myself qualified enough to answer. Run into the same quite a bit, routinely putting rod bearings in old junk.
Waiting patiently for Bob and Hobo to respond.
ok, good to go. back to work with no worries!
 

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