1 pc rear seals vs. 2 pc
Thread Starter
NCM Grand Opening Veteran
Joined: Sep 2005
Posts: 20,979
Likes: 384
From: South of giving a damn
St. Jude Donor '11, '17
1 pc rear seals vs. 2 pc
Anyone see any reason not to go with a 1 pc seal block? Blocks are the same price & the 1 pc block accepts hyd roller cams w/o modification or link bars. Going in my 79 with a TH400 behind it.
Team Owner
Joined: Jun 2001
Posts: 23,375
Likes: 1,067
From: Virginia USA
GM didn't change the rear main seal design after 50+ years because they though it would "look cool". Think about it, a split seal that has TWO more places to leak or one seal that doesn't have these splits. I'll leave the decision up to you but have you ever replace a rear main seal while the engine is in the car? I have and it's not that fun. Go with the one piece. 
Drifting
Joined: Aug 2004
Posts: 1,883
Likes: 124
From: Lubbock TX
Earlier 2-piece blocks tend to be thicker and cast with better material, particularly the 010/020 blocks. They would be the hot ticket for anything over about 450 - 500 hp that you plan to beat on regularly. For a good, hot street build 350 or 383, go with the 1-piece for less seal problems and ability to use inexpensive factory hydraulic rollers. If you're going to stroke it to a 383, cranks are about the same price.
Safety Car
Joined: Jul 2001
Posts: 3,921
Likes: 2
From: York PA
Originally Posted by jimmygmartin
You will need a different flywheel/flexplate.
I was looking at a one piece rear seal block because of the factory roller lifters. I think this is definately a good way to go. I ended up buying a 400 block, 
so I got a 2 piece rear seal.
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Le Mans Master
Joined: Aug 2003
Posts: 7,720
Likes: 12
From: Chattanooga TN
Originally Posted by L88Plus
Earlier 2-piece blocks tend to be thicker and cast with better material, particularly the 010/020 blocks. They would be the hot ticket for anything over about 450 - 500 hp that you plan to beat on regularly. For a good, hot street build 350 or 383, go with the 1-piece for less seal problems and ability to use inexpensive factory hydraulic rollers. If you're going to stroke it to a 383, cranks are about the same price.