Question Concerning New Pistons Installed in '46 JD B

Yesterday I installed new pistons in the bored out block of a '46 B. The business that bored out the block also provided the piston set with rings and fit the new wrist pins to the connecting rods. I was expecting the fit to be somewhat tight due to the new rings, but before buttoning it up I want to ask if there is an accepted way to judge tightness and "how tight is too tight." I can turn the flywheel with what I call a medium amount of effort, but my only frame of reference is how easy it was to turn the flywheel on that well-worn engine before I dismantled it.

A little additional information is the RTP pistons (with Hastings rings) are stamped .090". I checked the diameter of the bores and both appear to be in spec (4.5 + .090). The crankshaft turns freely in the main bearings, and the fit of the connecting rods to the journals and the wrist pins to the connecting rods is smooth and not bound up, so I don't see any issues there. Looking through the archives today, I saw where there have been different thoughts on using assembly lube versus motor oil when installing pistons. I used assembly lube. We have had a rapid warm up and the air temperature was in the 60's, but the heavier cast components were still cold from recent cold weather and the assembly lube was a lot more viscous than motor oil.

Any comments would be appreciated.

I'm working on a 50, bored .090, new everything, reground crank, and it's hard to spin over by hand, especially when it's coming up on the compression stroke. I used the assembly lube in a tube. I'm not ready to start it yet. Time will tell if it's right.

Yes, with new rings they are actually hard to turn over by hand. As long as the machine shop fitted the pistons and rings right it should be alright. With tighter rings the engine will run hotter, so I suggest taking it easy for the first hour or two until the rings loosen up. Then start putting it to moderate work.

I think you are OK. After the rings set it will be considerably harder to turn over by hand. I thought the same thing on my B's after rebuilt.

Thanks everyone,
I appreciate the responses.

Normally the machine shop will check and set the ring gap. Then mark which set of rings go into which cylinder. Same with cylinder bore; fit bore with proper clearance to piston and then mark number on face of piston as to which cylinder it goes into. Ring gap and piston to cylinder clearance are very important. Assembly lube on bearings and engine oil all over rings and piston and cylinder walls before sliding pistons in.

There is an accepted way but it's too late in the process for that now. Uses 18 inch feeler gauges and they are laid upon the bare piston and together as one, slid into the hole and then just the ribbon is withdrawn to 'feel' the clearance between cylinder and piston. It's the typical fitment manner in which cylinders are honed to proper size too, so the shop that did the work has already been there done that and given it the thumbs up way ahead of you. You can trust that they have double checked to protect their investment in your project too. They wouldn't be in business long if they didn't know how to do it stand straight up right.

Assembly lube can mean anything from STP motor oil honey to white lithium grease and the only thing we can really know from your use of assembly lube term is that you are so new to the game that you didn't know you were talking kindergarten speak to us - not that it matters one bit either. Overused word with so many categories, it just can't be used by itself to mean anything concrete to another human. No matter what it is, it always washes out with oil once running and seems to work just as good as any other. I prefer just motor oil for piston and rings, lithium grease for babbit bearings, camshaft lifters, and priming the oil pump gears. My mentor used STP in a squirt can but it didn't squirt that stuff, just drooled it out. And that would then drip and drip and drip and drip... Only got to try Lubriplate, a white lithium grease, after I had left my mentoring shop and liked it a lot more than the STP. It don't drip away and make a mess of everything.

When he said "before buttoning it up" I assumed he meant
the head is not on yet. I'm sure it will be harder to turn
then.

Everyone talked like the machine shops are always
right. I'm not saying yours has done anything wrong
but I will share some experiences.
Years ago I sent a 620 block 50 miles to have it bored.
It came back 0.125 over. There were no pistons available
that size. (M&W used to have them) The machine shop
didn't care. They should have known what was available.
I bought a used block and hauled it to a machine shop
70 miles away. It was to be bored 0.045. They did it
while I waited. I bought the kit from them. When I went
to install the pistons, they just laid in the bottom of
the bore. That clown bored it 0.095. When I called they
would sleeve it for no charge.... their mistake.
I offered to take the 0.125 block to save a step.
"Wait a minute" they checked and sent me 0.090 pistons.
Both the shops were well established, big-time shops.
They all mess up.

You're right - I missed that.

Yes, that is correct. Haven't put the head on yet. Wanted to run my question by the group before doing that.