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Cant spin crank

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Old May 15th, 2018, 10:54 PM
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Cant spin crank

I got my engine parts back from the machine shop and with the main caps tightened I cannot turn the engine over with the balancer bolt in. I installed #1 and when I installed #2 it became tough to turn. I put a plastigauge in there and it was tighter than .002. I think that's accurate, I tried not to rock the main cap when I took it out to check it. The mains and rods were turned 30 under, as the crank had been turned some time back in the 70's from some date coded bearings.

Rear main saddle at 120 ft lbs and all others at 80.
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Old May 16th, 2018, 02:01 AM
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Ask the machine shop to measure the block with the main bearings installed using a dial bore gauge, then mic the crank to verify clearances. There may be +.001" bearings available if it's too tight. Good luck with your build.
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Old May 16th, 2018, 04:53 AM
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What rear main seal are you using ? The rope seals can make the crank very hard to turn. Also, make sure you have the correct bearings in each position. If I remember correctly it is easy to mix a couple of them up on Olds engines.

What engine ? What part number main bearings ?
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Old May 16th, 2018, 04:58 AM
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Originally Posted by BillK View Post
Also, make sure you have the correct bearings in each position. If I remember correctly it is easy to mix a couple of them up on Olds engines.
What engine ? What part number main bearings ?
All the bearing halves are the same thickness except the rear, which can obviously only go at the position. #1 half has a different tang, but again can only go in one place.
Just because everything is in size doesn't mean it's IN LINE. Big difference.
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Old May 16th, 2018, 05:07 AM
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Originally Posted by cutlassefi View Post
Just because everything is in size doesn't mean it's IN LINE. Big difference.
Absolutely correct but if the engine was running before tear down and the crankshaft did not need to be reground again, the main bores are more than likely ok.

Originally Posted by cutlassefi View Post
All the bearing halves are the same thickness except the rear, which can obviously only go at the position. #1 half has a different tang, but again can only go in one place.
Why am I thinking there is one set of mains you can mix up and will cause the crank to tighten up ? I am thinking one of my customers had the same problem and that is what they had done. I don't have any Olds blocks in the shop right now to look at. I dont see enough of them to remember so you are probably right
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Old May 16th, 2018, 05:15 AM
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As Bill mentioned above, if you used the rope seal at the rear main it will make the crank more difficult to turn. The crank should spin free prior to installing any pistons. Also, did you check the ring end gap; did you remember to lube the cylinder walls? The rings will add a lot of drag, especially the stock type 5/64" rings.
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Old May 16th, 2018, 06:45 AM
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.030 main bearings were on national backorder. I found some oldies NOS on eBay. Federal mogul. This bastard won’t turn WITHOUT the rods in it let alone with.
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Old May 16th, 2018, 07:40 AM
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Might be a stupid question but are you absolutely sure the crank is .030 ? And are you sure the bearings are .030 ? What part number are the bearings ? The crank should measure pretty close to 2.970" if it is .030
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Old May 16th, 2018, 08:14 AM
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Just a KISS question.
You have put the mains caps back the right way round and in the right order?.
That is the tangs facing and the caps in the order they came off?.

Roger.
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Old May 16th, 2018, 08:55 AM
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Originally Posted by rustyroger View Post
Just a KISS question.
You have put the mains caps back the right way round and in the right order?.
That is the tangs facing and the caps in the order they came off?.

Roger.
Little dots in order 1-5 cast numbers all on one side. I'm sure the machine shop fucked this up.
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Old May 16th, 2018, 09:35 AM
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Originally Posted by NotDads442 View Post
Little dots in order 1-5 cast numbers all on one side. I'm sure the machine shop fucked this up.
What could they have done to mess it up unless they measured the crankshaft wrong. Was the engine running ok before with no major bearing issues ?
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Old May 16th, 2018, 09:37 AM
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Just thought of one thing. Are you sure you are putting the caps on correctly ? The little tangs that align the bearings should be on the same side on the block and the cap.
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Old May 16th, 2018, 10:37 AM
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Agree on getting the journals and bores mic'd, and/or you may have the wrong bearings. Take all the caps off and see how easy the crank spins. Then put one cap on at a time until it binds. If it binds right away, you have your answer on the bearings......
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Old May 16th, 2018, 03:13 PM
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It was the damn rope seal. Moving on to neoprene
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