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| | | | Joined: Dec 2011 Posts: 36 Wrench Fetcher | | Wrench Fetcher Joined: Dec 2011 Posts: 36 | So I recently picked up 261 block with rotating assembly and I'm not sure what rocker assembly I need to match it to. The casting number is 3769925 (inliners says 59-62 block) and the date code is Con 2 F 27 8 (June 27th 1958?). This block also has a clock like looking mark cast into it with the teardrop looking thing pointing at the one o'clock position. I would assume this motor needs the 58 rocker assembly, but under the side cover it has the oil line that goes from the rear cam bearing to the center of the block like the pre 58s did. This block is a full flow as far as I can tell based on the large tapped holes on the drivers side. Anybody familiar with a 261 that has the pre 58 rocker oil line and is full flow? I'd just like to know what parts I need to track down for its rebuild. | | | | | Joined: Sep 2001 Posts: 29,269 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,269 | 1958 rocker lubrication is different from earlier and later years. Here is some information. Yes, 1958 would have a full-flow oil filter set up (1/2 NPT oil line holes). | | | | | Joined: Jan 2001 Posts: 5,337 'Bolter | | 'Bolter Joined: Jan 2001 Posts: 5,337 | 261's do not seen to follow the same time line for changes as 235's.
A 1958 235 would not have the oil line behind the side cover.
If your 261 has the oil line it should have 1950-58 style rockers.
Those rockers will have the groove inside each rocker in the center and the rocker connecter tube will not be pinched off.
See the USA in your vintage Chevrolet! My Blog | | | | | Joined: Dec 2011 Posts: 36 Wrench Fetcher | | Wrench Fetcher Joined: Dec 2011 Posts: 36 | Thanks, that link really helped clear up the differences in the rockers. Luckily I happened to have picked up 235 rocker assembly before I got the block that looks like the pre 58 235 ones posted in the link and has the groove inside the rocker arms. I assume this means I also need the lifters without the notches in them? Are there any any changes they made other than the rocker oiling? And does anyone know what the small oil hole next to the lower 1/2 NPT oil hole in the block is for? | | | | | Joined: Jan 2001 Posts: 5,337 'Bolter | | 'Bolter Joined: Jan 2001 Posts: 5,337 | There is no problem using lifters with the reduced diameter in the center in any engine. You just do not want to use lifters without the reduced diameter in an engine that does not have the supply tube behind the side cover(1958-62 for 235's).
I believe the 1/8" pipe port is for the oil pressure gauge.
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