Engine turns by hand, with effort...

Henry's Lady's Man

Henry's Lady's Man

Senior Member
I removed one shim from my front main, and one from my rear main. They were foil-thin, and measured .001 each. All three mains are now .0015; I used assembly lube.
The engine turns by hand, but with about 20 lbs of arm pressure. The rods are not connected yet. Is this too tight to start? I'd hate to get the engine back in the car and find that the starter can't handle it.I would suspect that the ring gear will gear it down enough, but I just don't know. This is my first rebuild.
 
For whatever reason, it takes about 40 or 50 lbs of my pull to turn the engine now. does anyone have any advice on this? I can put shims back in the main bearings (babbitt) to make it turn easier, but only if it is advised. I've got them all torqued and cotter-pinned.
 
Try pushing the crank fwd in the block and turning it, then push it back and try it again and see if there is any difference.
Personally i would put the shims back in....
 
Oh, my engine is still on stand without the connecting rods on yet. no rope seals yet. This is just the mains that are tight. I was wondering JUST HOW TIGHT they should be.
 
Sounds too tight to me. Are all the bearing caps facing the right direction? Try loosening the nuts one at a time until it spins free
 
When you first tried it and it took 20 lbs. it had some lubrication on the bearings. When you turned it some of the lubrication came off. Then it sits and a little more is pushed out.
When you try to turn it again it takes more to turn it. That's why it might have taken 50lbs.
If you lubed it up again you might go thru the same thing. It sounds like the clearanses could be a touch tight.
 
I agree, with just the crankshaft mounted, this is too tight. It should take very little effort to spin just the crank.
 
The bearing caps are properly faced with marks to the front as originally. When I took the engine apart, the bearings, front to back had these clearances: #1 - .0002, #2 - .0015, and #3 - .0020. The babbitt was good, so I tried to get all the same clearance (and did). They are presently all .0015 ; It looks like I should have left the shims as they were.
 
I wonder if the crank journals are oval, and you are measuring the narrow part?

It should spin quite easily at .0015" clearance.
 
tbirdtbird said:
"This is my first rebuild."
What does this mean?
Is this a brand new overhaul? Fresh babbitt and all?
Or did you just adjust the bearings by removing shims
If just adjusting pre-existing babbitt, the rule of thumb is to never remove more shims from the center than you did from the rear. The reason for this is that the center wears the most. Which means the center may end up with .002 or even .0025, but so be it. I am guessing this is your problem. The crank should spin very freely at .0015 clearance on a fresh babbitt job
And of course the front seldom needs any shims removed.
Click to expand...

Here's a quick recap of my "first rebuild": Teardown showed loose valves and valve guides, and vertical scores in cyl #3. The crankshaft and babbitt looked good, with said clearances (.002, .0015, .002).
I put in new valves, guides and springs. Got new pistons, wrist pins, and rebabbitted connecting rods (they were all way off on weights (30g difference between them!)). I left the mains alone, except I removed .0005 shim from the front and the rear. I was surprised to find the center main to be the best tolerance of all.
This is where I am at... the main caps are on and torqued, and it's hard to turn. Pistons and rods are not in yet.
 
Tom Wesenberg said:
I agree, with just the crankshaft mounted, this is too tight. It should take very little effort to spin just the crank.
Click to expand...

Thanks Tom. This is the conclusion I am coming to. I am getting the same advice from all, which is a good thing. Better to take care of it now, before proceeding.
Thanx to all for the help. Chuck
 
I didn't know you could get main shims in .0005" thickness. I wonder if it wasn't thicker than that?
At any rate, I'd reinstall it.
 
Tom Wesenberg said:
I didn't know you could get main shims in .0005" thickness. I wonder if it wasn't thicker than that?
At any rate, I'd reinstall it.
Click to expand...

I just took ONE .001 shim from one side. That is .0005 from the whole thing, right? I believe it I took a .001 shim from both sides, It would make the whole clearance .001 difference. Correct me if I'm wrong.
 
you can get away with measuring the shims and OD of things with a caliper, but they really botch things up when measuring the ID.
You really should invest in some better measuring tools like T gauges and micrometers before going further. Or at least some plastigauge....
 
aonemarine said:
you can get away with measuring the shims and OD of things with a caliper, but they really botch things up when measuring the ID.
You really should invest in some better measuring tools like T gauges and micrometers before going further. Or at least some plastigauge....
Click to expand...

I used plastigage.
 
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