The Stovebolt Site Forums The Shop Area Engine Shop rope main seal question

Should the ends of the rope butt together/touch each other? I'm putting in a new seal and found that the shims didn't have a cutout for the seal, therefore the rope ends weren't butted together--the shim was between them. Thinking that may have contributed to my oil leak.

If it makes you feel better, go ahead and trim the shims so the ropes can touch, but I've never noticed a problem with a thin piece of shim stock between the upper and lower seals. It's much more likely that the bearings have worn enough to let the crankshaft bounce around on the seal and make it leak. Be sure to check and adjust the oil clearance while you've got the main cap off.
Jerry

Oil leak could also be from the rope itself. The new replacement rope is nothing like the rope from when the engine was built. Somewhere in the early 90's the rope material changed, it's pretty hard to make it last.

Best Gasket Company is now selling material similar to what the original was. I have had really good luck with it selling and lasting.
Joe

I have tried the old trick with rope seals that you use with the rubber seals by rotating the upper and lower sections so the end are 10° to 15° past the parting line of the main caps. I had never had any leaks with rope seals before this anyway, but I just wanted to see if this added an extra measure of leak prevention. It worked great as well. I've also used that trick on other engines that use rope seals also, like several Pontiac V8's with no problems either. This may add an extra measure of prevention if you want to try it too.

I wish I would have trimmed my shims as suggested by HRL. Oil will find a way through those shims by capillary action if nothing else. I have a leak, but it is very slight.
Carl

I would not recommend trimming the shim. Unless the shims are touching the seal, any void between the shim and the seal will leave a path for the oil to migrate.
Although the shims do not fit tight against the crank, the ends of the seal will fill that small area.
If this is not clear I can take some pictures, there worth a thousand words.

Pics would be awesome. I don't have a clear picture of it in my head, as it was over 20 minutes ago (3 years actually) since I looked at one.
Carl

To answer your original question, yes, the ends of the seals in both the upper and lower halves should protrude slightly as to allow the seal halves to form closure between each, or they can leak at these points of contact, or for better terms, a lack of contact.

These look to be cutout for the seal, are yours?

http://www.jalopyjournal.com/forum/attachments/wp_20131018_010-jpg.2055650/

The rope ends must touch, and each side should be slightly higher then the cap and block so when they are bolted together, the seal is pressed together forming one continuous seam.

You want to get a Best Gasket rope seal kit. It includes the best rope seal you can get now a days as well as a cutoff tool and gauge. also has instructions.
Rope Seal Kit

I exaggerated the cutout in this shim for effect, but any clearance between the seal and the shim is a path for oil. link to picture.
I used a neoprene seal for the picture because I had it handy, but the effect is the same with a rope seal.
It is true that if the ends are cut a little high they will likely smash out and fill any gap.

A small dab of brush-on Permatex between the cap and the block makes all the discussion about tiny leak channels a moot point.
Jerry

Went ahead and made a cutout in the shims and added a dab of sealant to the rope ends which I'd read somewhere (shop manual probably) not to do. Only a short drive so far and no leaks yet. Time will tell. Thanks for all the input.

If it doesn't leak, how will you know when to check the oil level?