Torque required to turn over new engine...

[Dan Truax]

So I rebuilt my 51 8N engine, new sleeves, reground crank and everything.

As I installed each piston I made sure to turn over the engine by hand.

With all 4 pistons installed it took 40ft/lbs to crank which isn't bad.

But with the new rope seals in and the oil pan installed it took 80ft/lbs.

Is that normal?

I installed the old 6V starter and tried to crank it over today and the starter solenoid welded itself closed and the starter made itself into a heater before I could disconnect the battery cable.

Was the solenoid and/or starter weak or was the 80ft/lbs too much for any starter?

New starter ordered and on the way in the mail, old started was tested with 12volts disconnected from anything and it is definitely fried...

Thanks for the help again... -Dan.

 

[grizz02]

should be able to turn that motor just buy holding tension on the fan belt and moving the fan blade , something does not seem right , with the plugs out it should roll over easy , did you check ring end gap?

 

[Hobo,NC]

I checked one, one time after I had the pan on head off it took 70/ 90 you are good to go as far as the engine is considered...

 

[Dan Truax]

I can't move the motor with the fan blade, I tightened the generator pulley with a crowbar and cranked down on all the nuts.
But the fan pulley slips.

But she rolls over with 80ft/lbs on the crank bolt WITH the old plugs in. I was using them to keep dirt and paint out.

Checked the gap on the rings and it was wide but in tolerance. Seems the factory rebuild kit rings all come with a too big gap. So that doesn't seem to be the problem...

Maybe the old solenoid and/or starter was weak. The brushes were sure beat when I took it apart to look at the damage. I'll make sure to have a way to disconnect the battery quicker if that was not the problem when I get the new one... with a new solenoid...

 

[Royse]

I never measured the actual torque it took to roll mine over after
I rebuilt it, but it wasn't something you were going to turn over
with a ratchet, even on the stand. It took a breaker bar.
I used a one piece seal in front and the rope seal in the rear.
It rolled fine with every cylinder assembly, as you said yours
did, but it was tight once everything was assembled.
My 6V starter turns it over fine though. Every time. Fires right up!

 

[Royse]

"I can't move the motor with the fan blade"

I can't move mine that way now either, but I could before I rebuilt it.
I was able to do the same fan trick on many other N's I owned too.
I would guess it is normal once everything was worn in well.

Don't tighten your generator that tight. The bearings won't like it.
Leave a 1/2 inch of slack in the long side of the belt.

 

[showcrop]

Dan, that is not unusual with rope seals. I have done a few. I think I turned my Oliver 70 100 rotations with my 3/4 drive to loosen it up. I used the two piece neoprene in my 961. I recently did the motor on my 1967 Datsun. Before doing the seal I looked at Utube videos. I found one on installing the rope seal on a Holden V-8. The guy raps his mandrel with a hammer a couple times and squishes the seal. I did that and I have around 40 lbs. I recommend watching that vid.

 

[Jim L WA]

I agree with most of the others, 80 ft/lbs is not too tight for a just put together engine. But what the heck happened to the start circuit? There had to be a direct short to ground through the starter it sounds like. Was it wired correctly? Did you have the starter apart maybe, and the battery post got shorted to the case?

 

[Dan Truax]

(quoted from post at 09:50:21 04/28/19) Did you have the starter apart maybe, and the battery post got shorted to the case?

Maybe, the part that melted and re-soildifed was the copper bar btwn the two windings on the outside case field coils. The insulation on the field coils was toast.

I don't know, I would have stored the starter with a nut on the long bolt had I'd known.

Mechanically inclined but mechanically inexperienced... (shrug)

 

[Dan Truax]

Thanks for the feedback, new starter in and turned over fine.

I either dead shorted it putting it back together or it was ready to give up the ghost, either way its got a new starter. Already rebuilt the generator.