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View Full Version : Tight Crankshaft (engine reassembly)



Falkon
05-20-2011, 11:50 PM
After a few hours of reading directions, searching for lost parts that are right behind me and triple checking everything i could think of, I finally got the basics of the lower half of the engine put together. This includes; pistons, rods, crank and cam shaft, all new bearings etc.

As soon as all of this was done i tried to turn the crankshaft and noticed that it was not the easiest thing to do. You can barley turn it by hand. I did manage to turn it over a few times just to make sure nothing was grinding but even after re-lubricating the bearings its still very stiff. The Pistons fit nicely so i don't think its those. But obviously I don't know the really reason why it is doing this so that why iv come to ask the experts.


All other engine reassembly questions i have i will also post here.

smaceng
05-21-2011, 12:47 AM
I'm sure the experts will chime in here, but it is a matter of elimination. Did you check any of the rotating items prior to connecting them up? One should always take baby steps in assembling an engine. Crank first, then check if it rotates OK, then one piston and rod at a time. Then assemble the cam, check it for rotation. Then add the timing chain/gears. So, to find out what is tight, do all the steps, but in the reverse order. If you find out that one item is too tight, and it was not an assembly problem, then it is best to take it to the machine shop and let them fix it.
Good luck,
Scott in CA

racingenglishcars
05-21-2011, 12:50 AM
The largest source of friction by far is new tight rings sliding in newly honed cylinders.

Now is the time to degree your camshaft!

Gerard
05-21-2011, 01:12 AM
For this reason, it's a good idea to check your tolerances with Plasti-gauge first to make sure the crank bearing were finished to the right tolerance. I always check both rods and mains. You don't say if your bearing are STD or oversize. If you think it's unreasonably stiff, bolt up just the mains and see how it feels. You should be able to turn it by hand and it should feel smooth throughout the rotation.

How does it feel if you put in the pulley nut and turn it with a moderate length breaker bar?

jlaird
05-21-2011, 09:12 AM
I would bet that it is just fine. New rings against newly refinished cylinder walls creates a bit of friction. Being able to turn it over by hand sounds just about right to me.

Falkon
05-21-2011, 11:01 AM
I did put new bearings in and they are all standard. The cylinders have been honed to .02 and i have put in new pistons and rings that are .02. As i disconnected each rod and piston one by one the crankshaft did become easier to turn. And if you put a 1 ft breaker bar on it you can turn it with just your pinky finger.

Roger
05-21-2011, 12:43 PM
Just a thought - did you gap the rigs correctly?

Gerard
05-21-2011, 01:22 PM
I did put new bearings in and they are all standard. The cylinders have been honed to .02 and i have put in new pistons and rings that are .02. As i disconnected each rod and piston one by one the crankshaft did become easier to turn. And if you put a 1 ft breaker bar on it you can turn it with just your pinky finger.

Sounds like you're good... :cheers:

recordsj
05-21-2011, 01:24 PM
did you match all the bearing caps to its mate?

Falkon
05-21-2011, 01:31 PM
Just a thought - did you gap the rigs correctly?

No we did not. I didn't know that you had to gap rings. I pulled one piston out and it definitely needs the rings gaped. They are practically touching.

Now knowing that I have to gap the rings. What would be the proper way to gap them without the professional ring gaping tool.

https://oi56.tinypic.com/1570wlz.jpg

Trevor Jessie
05-21-2011, 01:44 PM
Just out of curiosity, what brand rings are those?

Falkon
05-21-2011, 02:20 PM
I ordered them from NorthWest Import Parts. The Box that the piston and ring set came in was from Sakura Pistons.

jlaird
05-21-2011, 02:26 PM
I must say those rings are too large and need cut down a bit.

take em to your friendly engine builder for cutting. Bigger gap is better than smaller.

Trevor Jessie
05-21-2011, 06:50 PM
You can get a reasonable ring filer for $30. I wouldn't try to do them free hand.

regularman
05-21-2011, 08:13 PM
How much gap have you got? I usually give the pistons and rings to the guy that bores the holes and let him do all that checking. I don't know how everyone else does it.

TOC
05-21-2011, 08:24 PM
In the old days, nobody gapped rings.....and often you had to tow the car with a rope to get it lit the first time.
The ring ends look like they're touching.
Too Tight!

regularman
05-21-2011, 08:35 PM
In the old days, nobody gapped rings.....and often you had to tow the car with a rope to get it lit the first time.
The ring ends look like they're touching.
Too Tight! Yeah, that is what I was thinking. As long as he has some gap it might be ok. Its a water cooled car engine. I have played with a lot of air cooled motorcycle engines and they are not so forgiving. Everything swells quite a bit on them and so the guy that bores the jugs gets everything so there is ample gap when the aluminum pistons swell and everything. They usually mark it each piston for each hole so that they can figure for any differences from spec on anything.

Falkon
05-21-2011, 08:52 PM
I found a video tutorial on how to gap the rings by Moss. I'm thinking that's how I'm going to do it. All i need is the feeler gauge which i cant seem to find any where.

Also, there seems to be a bit of surface rust showing up on the cylinder walls. I can still wipe it off with my fingers but knowing that it was rust that originally caused the engine to seize, how exactly can i stop it from continuing until i have the head completed and done.


https://www.youtube.com/v/1ZiqnychIcUnychIcU" type="application/x-shockwave-flash" wmode="transparent" width="425" height="350"> </embed></object>

TOC
05-21-2011, 09:22 PM
Oil. You squirt oil on the walls (I just use 30WT, but probably use what you're gonna use in the engine), wipe it down......and soak the ring grooves behind the rings.
Make a mess.
Rust means unprotected metal,,,,,it won't be as susceptible once it's burnished by running, but right now, maike it oily.

TOC
05-21-2011, 09:24 PM
Hang on....is this your first engine rebuild? You DO know to "stagger" the ring gaps? You know for sure which side is "up"?
Just checking.
Dave

Falkon
05-21-2011, 09:40 PM
No this is not my first engine rebuild and yes i do know to space the ring gapes by at least 40 degrees and yes i just watched a moss video telling me which side is up for the one ring that is not marked "TOP"

JPSmit
05-21-2011, 09:43 PM
you can buy fogging oil at the usual places - puts a thin coat of oil (aerosol)

TOC
05-22-2011, 03:41 PM
Not flipping you anything that should be considered a hard time.
I read your lead-in to this thread:
"After a few hours of reading directions, searching for lost parts that are right behind me and triple checking everything i could think of, I finally got the basics of the lower half of the engine put together. This includes; pistons, rods, crank and cam shaft, all new bearings etc. "

and just thought I'd ask to make sure.

If this WAS your first (and nothing wrong with that....we all have to start somewhere), step-by-step instructions would have ben in order.

As far as lubricating rings, ring grooves, wrist pins and such...I miss the old days when oil came in round cardboard cans with metal ends.
We'd fill our oil cans, then cut the top off, and dip the fully assembled piston and rod in until the wrist pin was covered for pre-lube.

Come to think of it, I think I still have one or two of those unopened cans on my shelf....

Falkon
05-22-2011, 04:34 PM
This is my second engine im rebuilding, the first was our 97 BMW 318ti. So I know the basics to watch for but there are still a lot of difference between the two engines. And i mean A LOT. So even thou this isn't my first time, there are still a lot of things i can learn and other things i might still not now. So keep the advice and tips coming, they are still helpful.

Guest
05-22-2011, 06:03 PM
Where'd the lost instruction post go?

Falkon
05-22-2011, 06:21 PM
I found the instructions and figured i might delete the post so i didn't cause any unnecessary problems.

The one marked TOP goes second and the TOP means the direction it faces. And i already had the oil rings in first. I'm just gaping the rings right now.

Guest
05-22-2011, 06:25 PM
What's your gap at? IIRC, .003 for every inch of bore for stock N/A stuff.

Falkon
05-22-2011, 06:32 PM
Top rings are at .014 Books says .011-.016
2nd ring is at .010 Books says .008-.013

the cylinders are bored out to .02

Hap Waldrop
05-22-2011, 08:15 PM
Ring gap formula

bore size x .0045" for top compression ring
bore size x .0035" for second compression ring
Oil control ring minimum .015"

Falkon
05-29-2011, 07:10 PM
I new this would happen at some point and it will happen again, but im missing 2 bolts screws that go into the engine. I have bolt that fit but they are flat so they don't fit correctly.
Now would it be ok to use some bolts that will fit the thread and are the correct length, or do i have to find the exact correct type of bolt for the empty holes?

The bolt holes im talking about are the 2 bottom ones in the picture.
https://oi51.tinypic.com/talm3l.jpg



Also after im done timing the engine and have most things together. How do i know the correct way to place the Distributor Spindle back into the engine? What direction should the slash on the end be facing? If you don't know the part im talking about its number 49 in this image.

https://www.mossmotors.com/Graphics/Products/Schematics/SPM-003A.gif

Gerard
05-29-2011, 09:04 PM
I new this would happen at some point and it will happen again, but im missing 2 bolts screws that go into the engine. I have bolt that fit but they are flat so they don't fit correctly.
Now would it be ok to use some bolts that will fit the thread and are the correct length, or do i have to find the exact correct type of bolt for the empty holes?

The bolt holes im talking about are the 2 bottom ones in the picture.
https://oi51.tinypic.com/talm3l.jpg



Also after im done timing the engine and have most things together. How do i know the correct way to place the Distributor Spindle back into the engine? What direction should the slash on the end be facing? If you don't know the part im talking about its number 49 in this image.

https://www.mossmotors.com/Graphics/Products/Schematics/SPM-003A.gif


The screws you need are 1/4"-28x1/4" or 1/2" socket head.

Drive spindle is approximately 2 and 8 O'clock, with the large offset uppermost.

I gather you're doing your build without a Bentley manual? You really should invest in one.

Falkon
05-29-2011, 09:21 PM
This is at TDC correct? I do have a Haynes Manuel, but its very vague on the spindle position subject.

Gerard
05-29-2011, 09:36 PM
This is at TDC correct? I do have a Haynes Manuel, but its very vague on the spindle position subject.

Yes, #1 TDC on it's compression stroke. Line up the dimples in the sprockets or timing mark on pulley to pointer if you have your timing cover on already.

I don't care for most of the others. The Bentley is the #1 manual to have; others are OK to have, but as supplemental, in my opinion.

Falkon
06-10-2011, 09:46 PM
I cant seem to find the correct type of bolt ANYWHERE I looked at Ace, Big R, Fastenal, Wrench and Hammer, Lowe's, Home-depot, and a few more. No one has it. I do have ones that fit but they don't have the counter sunk head. Also the ones shown on Moss do not look like the correct ones. They look like the one that i have in the picture. Any idea where to get two of these bolts.
https://oi55.tinypic.com/1iicgl.jpg

Gerard
06-10-2011, 10:03 PM
I cant seem to find the correct type of bolt ANYWHERE I looked at Ace, Big R, Fastenal, Wrench and Hammer, Lowe's, Home-depot, and a few more.

You usually have to look in the special assortment they usually hide behind the counter, I'd be very surprised if you can't find this in a local hardware store like an Ace.

Anyway, this is the one. Look at McMaster-Car under Socket Cap Screws or search the product # below.


Black-Oxide Alloy Steel
1/4"-28
3/8"

qty 50 91253A301* $7.50

https://www.mcmaster.com/param/images/scs/alloyflatfull.gif

https://www.mcmaster.com/

TulsaFred
06-11-2011, 12:33 PM
I'm rebuilding a 1275 and ran into the exact same problem. After putting the new bearings and rings in place the engine was extremely hard to turn by hand and seemed to hang up at a particular portion of the rotation.
Turned out, IIRC, that I had installed the center main cap backwards. It looks symmetrical and will bolt up either way. When I turned the cap 180 degrees and rebolted it, the problem was fixed.

Fred

Falkon
06-13-2011, 11:14 AM
Sometimes its the simplest stuff. Turns out i put the thrust washers in backwards. After i flipped them around it was a bit easier to turn but its still not easy to turn by hand. I know that all the rods and bearings are facing the correct direction and the center main bearing cannot be placed in the other direction because of the Collars that are on it. The collars are shown in the picture below.

https://oi51.tinypic.com/r73ddg.jpg
This pic was taken before i turned all four thrust washers around.

Gerard
06-13-2011, 04:46 PM
I hate to be the one to tell you this, but if you torqued down the caps while they were on backwards, you might have tweaked them. Did you have the block line bored and the rods reconditioned in the first place?

Falkon
06-13-2011, 06:29 PM
I had not torqued the down yet, and since I dont know exactly what u mean by having the block line bored I would have to say no on that one, but I do believe I had them recondition the rods. I have to check the reciept cause I don't know for sure.

BugeyeNJ58
06-13-2011, 07:09 PM
Might be a good time to have some liquid refreshments while you're going through the receipts. Many times I have to take a break and then get back to it.

Gerard
06-13-2011, 07:22 PM
I had not torqued the down yet, and since I dont know exactly what u mean by having the block line bored I would have to say no on that one, but I do believe I had them recondition the rods. I have to check the reciept cause I don't know for sure.

Line boring is a similar process to reconditioning rods. It is the process of making sure that the journals that hold the crank are truly round and properly in line with each other, and also within tolerance to fit the bearings and crank. This should include the or half moon seal (some call it an "eyebrow") at and above the rear main cap. It should be SOP for rebuilding an engine.

Falkon
06-13-2011, 07:41 PM
Yes the rods were checked and reconditioned. And I did have an ice cold cup of my special mix sweet tea in the process.

Gerard
06-13-2011, 07:55 PM
Yes the rods were checked and reconditioned. And I did have an ice cold cup of my special mix sweet tea in the process.

But not the block?

Falkon
06-13-2011, 08:05 PM
No

Scott_Hower
06-14-2011, 01:36 PM
No

I'm surprised the shop didn't recommend this. Was the crank ground or just polished?

Falkon
06-14-2011, 05:26 PM
They polished it