348 rear main

[models916]

I lost track of this topic. Did we ever figure out if the early 58 348 blocks could ONLY use the rope seal? I have a later 58 block and used the NEW style seal without problems. Somebody was having a provlem with the rope. Fill me in on this.

[Ronnie Russell]

models, I believe it was Dunhamfield that had that problem. The way he described it, the early 58 had to have rope seal. Havent ever run into it myself, so I must say, ' I dont know".

[dunhamfield]

Yes there was a casting change. I thought that the change was made at the same time that the 60 block started putting water jackets around spark plugs.
Mine is a early 58 and the casting groove is different than 60 blocks.
I have seen mine and its a v shaped groove that will only take a rope seal.
I saw a 60 block and the casting groove was more squared off for the neopreme seal.
So I guess that the casting change happened in late 58, if yours takes a neopreme seal.
We did finally get mine to quit leaking. The machine shop knurled the crank at the sealing surface to pump oil away from the seal.