Here’s the actual size I didn’t find right away:
So you’re right, a small but noticeable difference is definitely there.
So perhaps the tool should not be used when the crank has been ground???
Dennis 69 OTS
The rope seals on the crank scroll, not the journal, so I don’t see how grinding the journal should have any effect on the rope seal. What am I missing?
Oops.
Yes you are right.
Dennis
Of that, Bill, I have no doubt!
What I did when using the crank, was I would use a dead blow or soft hammer to hammer home the last bits of the rope seal on the block and in the main, after using the crank as intial setting “tool.”
When I was done with that, I would then gently roll the rope seal with a large round socket all around its circumference and then I would put the crank back , in with graphite grease on the rope seal and turn it by hand a few dozen revolutions, I never had a single rope burn-out problem, on any rope-sealed engine I worked on.
I have to admit that until I joined this forum way back in 2003, I wasn’t even aware that there was a special tool just to size the rope seal!
I’m impressed you guys can measure rope to the thousandths! 
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Hello Paul,
I have a colleague that uses nothing else than the wooden handle of a hammer and seems to have success, but at the end of the day, the crank would do the sizing. The seal does relax in the areas where its Not Tight on the crank and the areas that Are Tight will be displaced to some extent. Being involved in a world of precision for a great deal of my working life, this is too hit and miss for me.
I also have and use all the gadgets because I can. I have the facility to manufacture the special tools and in most instances, better than those conjured up by Jaguar, simply because I have the advantage of examining the function of their working tools.
I have a myriad of special tools for use when refurbishing Gearboxes and Differentials. I use a CNC machining Centre as a Coordinate Measuring Machine, for example, when setting the relationship between the Pinion and Crown-wheel. And a fixture that facilitates the measurement of the Lay Gear Cluster End Float with a Dial Indicator, rather than with a Feeler Gauge.
I’m not looking for a size, but a feel of resistance. You could size the bore created for the seal, remove the crank or whatever is being used, reassemble the cap and measure the bore immediately and then again five minutes later and the size will be different; there is quite some resilience in the seal material.
My final test for size is 25lb/ft torque to start the crank turning and keep it going. The many varying sized sleeves I have for my sizing tool allows me to hit this number consistently. I’ve never had a rear seal leak, but my colleague that sizes with a hammer handle makes the same claim. However, he’s not sure of the result until the engine is running. I’m confident of the result when I’m assembling the engine.
Regards,
Bill
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Bill, this 25lb/ft value, is without pistons or with pistons? Hopefully next two weeks I‘ll assemble my 4.2 engine. I had the sizing tool made so I have that.
Hello Martin,
Yes, just the bare crank.
Regards,
Bill
So that’s breakaway torque, but what range would be okay for you?
It has been many years, but that sounds lije the number I observed on a torque wrench, when doing the initial turnover.
I totally get, appreciate, and understand your methods, and were I still into this game, would likely adopt similar methods.
All I can say, in my defense, is the many hundreds of rope-sealed engines I built, from old Fords and Chevys, to a multitude of A-Series Austins, Rovers (up to the P6: they grew a brain then and used a neoprene seal), Triumphs, and MGSs, I too never had a leak.