Getting a Clean Cut on a Rope Seal

[mummyjohn]

The Fel-Pro full gasket/seal set for 472/500 motors has rope seals for the crankshaft rear main seal.

I used a large-size socket to pound the thing in, and when I was finally ready to cut off the excess rope I used a brand new single-use razor blade.  It was about as difficult to cut through this rope as it is to cut through glass with a stick of butter.  I couldn't believe it.  After a while I tried my X-Acto knives instead, which was only a tiny bit more effective.

Still, it was an absolute chore to cut these things, and the result is obnoxiously frayed and messy, not at all like the "clean, flush cut" I keep hearing on every 'how to install rope seals' page.

So I'm asking you guys...what's your advice on installing rope seals, particularly the cutting step?  Is the tool simply not sharp enough (it's the sharpest damn thing I own!)?  Is this an easy job to botch and is it worth using a neoprene split seal instead?  Help me outta the woods gents...

[fishnjim]

One of those look before you leap kind of things.   They should have instructions in the gasket set or contact the seller or manufacturer or in the Cad shop manual.   There's online resources, if you search.   It's a bit of an art/lost art but not that difficult.   It's still common in industry for gland seals.  Generally, packing is cut/trimmed to size before installation.   It should be pushed in smoothly/squarely not hammered in. 
There's a special cutting tool for packing.   But a standard pair of guillotine cutters, with a sharp blade like Sears handi-cut should work.   A clean cut is needed so it compresses properly.   If multiple wraps, like a gland, ring cuts are clocked so the splices don't line up. 
Face seals didn't come until around til the late 50s.   If the surfaces are machined them it's probable to change.   But better to have the machinists fit during rebuild.

[Caddy Wizard]

The only way to cut the rope seal to ensure a drip-free cut...is to cut the damned thing in half and install a neoprene seal instead!  Every time that I have used a rope seal, being as careful as possible, the darned thing still leaked a little after a short time in service.  By contrast, when I use a neoprene seal, I get a drip-free installation every time...

[The Tassie Devil(le)]

I find that the only way to cut the excess from a rope seal in to use a very sharp blade, as in those break-away bladed knives, and if there is any "roughage" poking up, carefully manipulate this into a point, so that when the two halves are put together, they compress themselves as they go together.

Before the days of these "box cutters", I simply used a sharp knife and in a sawing action, cut in towards the mandrel I was using to set the seal into place.

Yes, you have to roll the seals in, and the mandrel is helpful, but a large socket or pipe will work just as well.

Bruce.

[squirrel]

I recently did a sort of overhaul on a 346 flathead...and I decided I'd never be able to get the seal cut right, so I just left the old seal in place, and re used it. The engine does not leak any oil I think I made the right decision.

[gary griffin]

I use a "Sneaky Pete" to pull the seals through the groove. I think they are still available on eBay for less than $10.  Small cable with a handle on one end and a clamp on the other end. Push the clamp through the channel and clamp on the rope seal and push one end while gently pull the handle.

[The Tassie Devil(le)]

Yes, but you still have to cut the end, or both ends once you have pulled it into place.

Plus, with these "Sneaky Pete" installations, how does one compress the internal parts of the seal, after it is stretched whilst installing?

Bruce.