Reply to "Leaking rear main seal - sometimes!"

With one h---uvalota work, a 351-W (also marked 'for 351C') teflon one-piece rear seal from Rock Auto can be adapted to a 351-C. It takes careful machining to cut away the std seal holding grooves in the block and rear main cap, but then the one-piece supposedly-lower-friction 'racing' seal will fit. I did this for a friend a few years ago but as it wasn't my engine I can't say how it lasted.

I'd consider this a 'last resort' type of mod since it alters a rare Cleveland block. Dunno- looking at the result, it may be possible to fabricate a filler piece that once again accepts the std two-piece main seal.

And although this post was about a leaky rear main, remember that many parts houses will try to sell you a Windsor FRONT main as '351C equivalent' as rear Cleveland front seals are getting scarce. Sure, it fits but the identically sized Windsor front seal has no locating lip so you have to be very careful in seating the Windsor seal to the right depth in a Cleveland front cover. And R&R-ing such a seal requires pulling the Cleveland front cover off the block to drive the lip-less seal out.