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How hard should it be to manually turn engine?

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KenlyNC Cub
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Zip Code: 27542
Tractors Owned: 1947 Farmall Cub
Location: Kenly, NC

How hard should it be to manually turn engine?

Postby KenlyNC Cub » Sun Feb 26, 2017 6:41 am

I'm back to rebuilding my 47 Cub after several years off. I had to replace my crankshaft and it was measured properly and new main and rod bearings ordered. Now when I tighten it all to torque specifications I can not turn the crank at all manually. If I loosen the nuts a bit then I can. Is this normal? I don't want to continue until I know for sure. All the piston are in the correct cylinders with matching letters on the rods which are on the can side. I have only gotten this far by the help from this forum so thank you all so much!

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tst
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Re: How hard should it be to manually turn engine?

Postby tst » Sun Feb 26, 2017 7:41 am

did you plastic gauge the bearings after you installed the crank to check for correct clearance ? did you end gap the piston rings to specs?

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artc
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Tractors Owned: Restored: 1950 Cub, 1950 Cub Demo, 1948 super AI, 1935 Silver King, 1946 Oliver 60 RC, John Deere M, 1950 C demo.

In working clothes:
1950 cub, 1948 cub, 1941 A, 1948 H, 1963 B414, 1958 240U, 1947 Oliver 60 industrial, Oliver 70 industrial. IH 450, 1963, another 1948 cub, 1946 I6 with Trogan front blade.
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Re: How hard should it be to manually turn engine?

Postby artc » Sun Feb 26, 2017 7:59 am

since you replaced the crankshaft, i suspect that the crankshaft is a later crank, and you are installing the wide rod bearings that are used with the early connecting rods. these wide bearings interfere with a larger radius left on the rod journals meant to be used with the narrow rod bearings.

in this case, you can either replace the connecting rods and bearings, or (and i haven't tried this, but it ought to work) file the edge of each rod bearing to relieve it.

We had this exact issue at a Cubfest northeast on a motor i was building out of parts for Cecil.

also, did you look at every bearing to see if it was correctly marked, and was your crank polished? leftover babbit on the crank can cause the problem as well.
'If they're tappin', they're not burnin'
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KenlyNC Cub
10+ Years
10+ Years
Posts: 55
Joined: Sun Oct 17, 2010 1:56 pm
Zip Code: 27542
Tractors Owned: 1947 Farmall Cub
Location: Kenly, NC

Re: How hard should it be to manually turn engine?

Postby KenlyNC Cub » Sun Feb 26, 2017 8:36 am

Tst thanks. Didn't plastic gauge. Piston rings good.
Artc thanks too. Yep no idea year of crank. Maybe the guy I bought it from can tell me. I may have to try the filing down before new rods and bearings.
Thanks again to both of you.

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ricky racer
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Re: How hard should it be to manually turn engine?

Postby ricky racer » Sun Feb 26, 2017 9:01 am

I suggest you always plasti-gage your crank and rod bearings. You put too much time and money into your engine rebuild to guess or hope your bearing clearance is correct.
1929 Farmall Regular
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artc
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Posts: 1871
Joined: Sun Mar 30, 2003 10:25 am
Zip Code: 06457
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Tractors Owned: Restored: 1950 Cub, 1950 Cub Demo, 1948 super AI, 1935 Silver King, 1946 Oliver 60 RC, John Deere M, 1950 C demo.

In working clothes:
1950 cub, 1948 cub, 1941 A, 1948 H, 1963 B414, 1958 240U, 1947 Oliver 60 industrial, Oliver 70 industrial. IH 450, 1963, another 1948 cub, 1946 I6 with Trogan front blade.
Location: CT, Middletown
Contact:

Re: How hard should it be to manually turn engine?

Postby artc » Sun Feb 26, 2017 5:20 pm

if its dragging on the edges of the rod bearings you will see the scuff marks when you pop the rod caps off. i'm assuming you used an assembly lube or at least oiled the bearings when you installed them.
'If they're tappin', they're not burnin'
http://www.ZagrayFarmMuseum.org

KenlyNC Cub
10+ Years
10+ Years
Posts: 55
Joined: Sun Oct 17, 2010 1:56 pm
Zip Code: 27542
Tractors Owned: 1947 Farmall Cub
Location: Kenly, NC

Re: How hard should it be to manually turn engine?

Postby KenlyNC Cub » Tue Feb 28, 2017 4:47 am

I got plastigage on Sunday and will perform that check some time this week and the other recommendations. I really do appreciate the insight and recommendations. I get on my phone very little during week so I'll see how this goes and perhaps start a new question if I'm still stuck. Thanks again.


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