Rear Rope Seal - Crank too tight - 8N

mcewan79

Member
Couldn't quite find this answer anywhere...

When installing the rear rope seals (heck maybe
even the front ones too), how flush should the
rope be with the body of the oil seal retainer?
I'm not asking about how much excess to leave
sticking up at the ends, but in body of the 'U'
should the rope be flush with the metal, or should
it stick up some?

I tried installing the rope seals (first time,
might not be a shocker) and ended up with the rope
sticking up 1/16" of an inch all around the body.
Probably about the same or less at the tips of the
rope too. It made the crank too tight. I had
thought that was normal and it would loosen up,
but the starter wouldn't turn the flywheel once
attached.

I used the dry method, per John Korschot's helpful
paper. After going back and opening up, I pulled
the crank up slightly, squirted some oil on the
rope, then let it sit overnight. It may have
gotten a little better but was still pretty tough
to turn. I then pulled out the rope retainer from
the block and crank spun relatively easily (still
somewhat tight, but I attribute that to new
pistons/sleeves/etc). I don't have a torque
reading, because of course the deep well 1-5/16"
socket I ordered ended up being too small (doh).
But, have another on order and hope to be able to
get a specific torque value at some point. To
that point, other than John's paper, I haven't
seen any info on what the torque required would be
to spin the crank once connected to all new
pistons &/or all new pistons+rope seals installed.
Ideally I can test and be confident prior to
resealing the block. I've seen things posted that
state anything from so tight you need to pull it
with another tractor to break in to so loose you
can spin it with two fingers.

I did plastigauge all main caps & all rod bearings
and everything looked good.

Long story I know, recap - should rope stick up
past side body of rope seal retainer (upper rear,
or all for that matter) & any info on torque
required to spin the crank.

Oh yeah, 1951 Ford 8N.
 
I just typed in, installing crankshaft rope seals in ford 8n, and up came some archived material on this site. Says you are supposed to soak the rope in oil for several hours and then install, leaving about a sixteenth inch sticking out. Never done it so don't really know how.
 

I have seen this come up here before, and it happened to me with an oliver 70 and a friend had it with a Ford 901. A rope seal is going to be tight so you need to turn it over about 40 times by hand with a big wrench to get it to loosen up.
 
I assembled my "dry" also (not soaking seal) but I had applied oil to seal part that contacted the crank keeping it off the ends. It was fairly tight but after all mains and pistons were attached it only took about 40 lbs of torque to turn it over. I have not got it all back together to try it with the starter yet.

As Showcrop said the more I turned it over the easier it got.
I don't remember how much if any mine stuck up out of the "U" shaped groove but I used a large socket to "seat" it into the U shaped groove on both the block and the pan.
I used the lip seal on the front Mine was a 1950 8n side mount distributor.
 
Pulling a new engine to start it gives me the creeps. I've done it, though. Once you are sure there isn't anything amiss then do it gently. I would probably pack the oil pump, keep the fuel turned off, and keep the plugs out. Pull it in about third so that the engine is spinning fast enough to pump oil but not racing engine speed. Pull it down the road a ways. If it has oil pressure that will be like driving it without that added compression. Then put in the plugs and see if she will start.

I know of a car that had to be pulled for the first year every time the weather was the least bit cold. It finally loosened up and made a good running car.
 
TJ (or anyone replying with torque guidelines)
I assume that 40lbs is with either head off or
spark plugs removed? I think this is a dumb
question, but...
 
Been a while since I've put a rope seal in, but I don't recall having one offer that much turning resistance.

They do mash out pretty wide, maybe 1/2 inch or so. That is normal. Now if it is really packing in hard between the flange and the crank, I guess it would be possible the rope is too big for the groove. The rope should be thin enough to seat to the bottom of the groove with only hand pressure. If the wrong thickness rope is used, as in too big, I would be more afraid of breaking something than having it too tight to turn.

One thing I always did, after leaving the ends standing up about 1/16 inch, put the lower half of the bearing cap or seal retainer on and tighten it. Then take it back off and trim the frayed ends away that squeezed out and got between the 2 mating surfaces, not so much trimming but scrape them back toward the end of the rope so they don't hold the mating surfaces apart on final assembly.

Just a tiny bit of gasket sealer, like Permatex, keeps oil from coming out under the bearing cap or seal flange, just don't get it on the crank.

If everything looks good, but it's still hard to turn, might try turning as you slowly torque the seal down, turn a little, tighten a little... See how it feels as it goes together.
 
Well, re-reading John's article for the 17th time, it might be sinking in. Sounds like his torque readings are -

Crank mains down & rear top rope - 10lbs
Above but with two pistons - 20lbs
Above but with four pistons - 40lbs

I'd assume this sounds right, based on other things that I'm starting to find online.

Using the little reasoning skill I have (and prolly still wrong), the torque of four pistons only (no main caps or rope) should be 30lbs). Sound logical?

Guess end of day, I can tinker around with all this stuff, just would like to have a good idea of what is too tight before sealing the engine back up...


Thx!
 
(quoted from post at 21:21:25 04/21/14) Well, re-reading John's article for the 17th time, it might be sinking in. Sounds like his torque readings are -

Crank mains down & rear top rope - 10lbs
Above but with two pistons - 20lbs
Above but with four pistons - 40lbs

I'd assume this sounds right, based on other things that I'm starting to find online.

Using the little reasoning skill I have (and prolly still wrong), the torque of four pistons only (no main caps or rope) should be 30lbs). Sound logical?

Guess end of day, I can tinker around with all this stuff, just would like to have a good idea of what is too tight before sealing the engine back up...


Thx!

I don't think that anyone is going to recommend that you really get this technical about it. The generally recommended procedure is to just quickly test rotation after each assembly step in order to easily ID a problem spot.
 
I worked for a car dealer for 40 plus years and in the special tools there were tools for flattening the rope seal, they were like a 2 or 3 inch cylinder cut in half with a handle on the flat side, you install the seal and rock the tool back and forth in the cap and block. Torque the cap, remove and trim any of the seal smashed out on the cap and block with a razor blade or exacto knife. I have used a socket or a hammer handle to flatten the seals too. Oil it.
 
GOOD post, GAB!

I was going to post about the tool last night, and didn't take the time to do all the typing to describe it. You did a GOOD job!

Here's a photo of a modern tool for old Chevies. I wonder if there was a similar tool for Ford "flatties"?

<img src = "http://i.ebayimg.com/18/!C!!ssow!2k~$(KGrHqR,!hgEzepylYIrBNB,F78O2g~~_12.JPG">



Here's another way to jam the seal in place:

<img src = "http://image.highperformancepontiac.com/f/tech/1306_engine_assembly_part_2_16_more_dos_and_donts/43410763/engine-assembly-install-rope-seal.jpg">
 

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