How difficult is it to turn an engine by hand?

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DartVadar

DartVadar

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How hard should it be to turn my LA360 by hand with the valve train and everything put together, so essentially the entire motor together. I know when the crank is in and mains torqued down it should spin easily, and with the shortblock together it should be more difficult but still spin freely.

I was just taking a look at my completed motor on the stand and was curious if I could turn the motor over by turning the harmonic balancer with my hands (spark plugs out of course!) it was fairly difficult (not much room to position hands around water pump) but I could get it to turn, I remember it was pretty easy to turn with a small wrench as well.

Should it be really easy to turn by hand? Or does it typically take some effort to turn the motor by hand? It was a freshly rebuilt 360 with the springs that come with the eddy alum heads. The bearings had all the correct clearances so I would really only be worried about the possibility of a bearing being misaligned or something. But if this would be the case would it be obvious that something was up with the bearings?
 
I used to be able to turn an engine by hand like that when younger, but not very far. Depends if the plugs are out.
 
67Dart273 said:
I used to be able to turn an engine by hand like that when younger, but not very far. Depends if the plugs are out.
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There is no way I could turn it by hand with the in, the compression is too high, I guess that means my rings and valves are sealing well. I'm probably just overthinking this, if I could only turn it with a breaker bar I would think there would be a problem.
 
Did you measure your bearing clearances? What are they?

As you install each piston, there is more drag. Usually by #5 or #6, it becomes difficult.


Or your pretty strong....
 
krazykuda said:
Did you measure your bearing clearances? What are they?

As you install each piston, there is more drag. Usually by #5 or #6, it becomes difficult.


Or your pretty strong....
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I personally didn't measure the bearing clearance but my grandpa did and said they were all good, the machinist that worked on the engine has worked on many of my uncles and grandpas engines, and everytime they checked over his work it was perfect, expensive as hell but does very good work. So I'm not worried about incorrect bearing clearances, I'm more worried about something not being lined when the bearings were installed. How hard is it for a bearing to no seat properly?

And yeah that sounds about right, after about 5 pistons I had to try a bit harder to turn the motor over.
 
my 360 with a stock bottom end , short block with plugs out took 25 lbs on the torque wrench to turn it, you can grab the balancer and turn it by hand
 
I have most of my 340 together, no room to get a good grip on balancer to turn it, but when i get home in a couple days I'll post what my torque wrench takes to turn it over. It turns over pretty easily, no pushrods in yet. Clearances were checked.
It would be hard for you to properly torque down caps and have a bearing cockeyed, if not impossible. Really cant see that happening.
 
Depends on the rings and the rear main seal used but normally I want something around 20-25lbs of torque to turn a fresh engine without plugs. Rope seals will add a little more resistance than lip seals, and lower tension or narrower rings will be a little less than factory ring widths and std tension oil rings.
 
totally assembled with the plugs in. It depends on what compression it has. The more compression the harder to spin it. Its shouldnt spin super easy.
 
I'll check to see how much torque it takes tonight. The engine has just under 11:1 compression so it's pretty high, that would make it harder I would assume. I will see the torque with and without plugs to see the difference.

All the caps torqued down nicely and were put on the right way so there shouldn't be an issue there.
 
DartVadar said:
I'll check to see how much torque it takes tonight. The engine has just under 11:1 compression so it's pretty high, that would make it harder I would assume.

All the caps torqued down nicely and were put on the right way so there shouldn't be an issue there.
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Without spark plugs the compression shouldn't matter. Compression comes into play with the spark plugs installed.

It's the drag/resistance due to the rings and bearing clearances/lubrication that you feel when trying to spin the crank.

If the clearances are right, there it should be tight to turn. If it feels too loose, then you may have too much clearance in the bearings (rod & crank) or maybe the piston to the cylinder walls.

If those check out ok, then good for you. You have a nice free spinning engine and it should put out more power as it is not using up as much to overcome the friction of the parts moving against each other (lower friction horsepower). If all of your clearances are right, then the easier it turns, the better....
 
krazykuda said:
Without spark plugs the compression shouldn't matter. Compression comes into play with the spark plugs installed.

It's the drag/resistance due to the rings and bearing clearances/lubrication that you feel when trying to spin the crank.

If the clearances are right, there it should be tight to turn. If it feels too loose, then you may have too much clearance in the bearings (rod & crank) or maybe the piston to the cylinder walls.

If those check out ok, then good for you. You have a nice free spinning engine and it should put out more power as it is not using up as much to overcome the friction of the parts moving against each other (lower friction horsepower). If all of your clearances are right, then the easier it turns, the better....
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The engine doesn't feel loose, it's pretty tight, but seems to turn without issues. All the clearances were good so I should be fine then. I'm probably just overthinking it.

If something was too tight would the force to turn it be excessive?
 
DartVadar said:
The engine doesn't feel loose, it's pretty tight, but seems to turn without issues. All the clearances were good so I should be fine then. I'm probably just overthinking it.

If something was too tight would the force to turn it be excessive?
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Yes. Try mixing a rod cap or two and torquing them. If there is any misalignment with the bores, I've seen cases where one wrong rod cap can lock up the crank from turning.

If you do try mixing the rod caps, make sure you mark them so you can put them back on the correct rod. I would do that on an old engine, not the one you are going to run. Try not to keep tightening the rod caps, as they stretch slightly every time you torque them. Eventually they can stretch too much and break....
 
krazykuda said:
Yes. Try mixing a rod cap or two and torquing them. If there is any misalignment with the bores, I've seen cases where one wrong rod cap can lock up the crank from turning.

If you do try mixing the rod caps, make sure you mark them so you can put them back on the correct rod. I would do that on an old engine, not the one you are going to run. Try not to keep tightening the rod caps, as they stretch slightly every time you torque them. Eventually they can stretch too much and break....
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All my rod caps were numbered, half the number on the rod and the other half on the rod cap, so when put together correctly the number is easy to see. And I don't really have an engine lying around to try that.

But I just used a torque wrench, I know it's not really that accurate, just good to get a general idea I guess. With the spark plugs in it took about 78 food pounds once moving and with the plugs out it took about 33 foot pounds once moving. But that was using a torque wrench that is about 5 pounds lower than the setting at lower numbers, so the 33 is more like high twenties, the 78 should be pretty accurate though. I couldn't find an adapter to use a smaller torque wrench so I had to use the big one. Those numbers seem pretty good to me. Nothing crazy.
 
Rodzilla said:
I went out and spun the short block and 26ft/lb to get it going. No pushrods installed yet.
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That seems about right, adding all the valve train would definitely increase that. So my numbers are pretty close to that. Im sure there is no need for concern in my case than.
 
DartVadar said:
That seems about right, adding all the valve train would definitely increase that. So my numbers are pretty close to that. Im sure there is no need for concern in my case than.
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Ya, I'd say you're ok there. As long as your still sure about clearances, on a stand I doubt you will see a difference on a torque wrench between .001" and .0025" but at 6000rpm your bearings will. Cheers
 
I checked mine yesterday since I was working on it most of the day..with a craftsman bar type TW it was 35 lbs with no plugs and valve gear installed...j
 
highflyer said:
I checked mine yesterday since I was working on it most of the day..with a craftsman bar type TW it was 35 lbs with no plugs and valve gear installed...j
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I found an adapter so I could use a more accurate torque wrench and it was 33 pounds with valve-train and no plugs, very close to what yours was. Glad to know its similar to other motors. I know my bearing clearance is right so I have nothing to worry about.
 
Then get-r in there and rev-r up. The way the weather has been you'll be out cruising in no time. A bud saw 4 Harleys in Red Deer the last two days, I think that's a bit crazy. I still have 2 feet of snow in my yard, and most residential streets are still packed snow and ice :shock:
 
Rodzilla said:
Then get-r in there and rev-r up. The way the weather has been you'll be out cruising in no time. A bud saw 4 Harleys in Red Deer the last two days, I think that's a bit crazy. I still have 2 feet of snow in my yard, and most residential streets are still packed snow and ice :shock:
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That's the plan! It'll be in the car in a few weeks! Just have to get my rear end swapped in there. And the weather has been really nice, the snow is melting pretty quick now. Time to bring out the toys!
 
I could have used the snapon [name dropper]lol,but I thot bar style would be good enuff...2 pnds diff, geez they give that on tolerance... I checked my snapon when I was working,it was one pound light at 100..id say close nuf tween us..j
 
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