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| | | | Joined: Jul 2010 Posts: 592 Shop Shark | | Shop Shark Joined: Jul 2010 Posts: 592 | When I pulled the rear casting plug yesterday on a 261 that I am rebuilding, I discovered something strange...two plugs in the same hole!
The rear plug is the one behind the bellhousing that fits in the 2" hole with the lip that takes a concave plug that gets tapped flat. The inner plug was steel and the outer plug was brass. I thought it looked a little odd that the brass plug was almost flush with the edge of the block, but didn't think much of it until I took off the brass one to find a steel one underneath it. The two plugs fit fine.
Could be that there was a leak and someone took an easy (or brilliant) approach to fixing it by adding a second plug? Or was this done as a belt and suspenders approach intentionally when the engine was put together to keep the plug from ever leaking because it is not easy to get to when the bellhousing is in place? Even with the forethought of using two different metals in case one gave out?
Thoughts? I've never seen it done before, but now I'm thinking that I should do the same thing when I put it back together since two plugs fit just fine.
Also, anyone know where to find 2" brass concave plugs? The 1 5/8" brass cup style plugs for the sides of the block are easy to find, but I have only been able to find steel 2" concave plugs. I'd prefer to use brass if I can find one...or two!
Opinions welcome...thanks,
Matt
| | | | | Joined: Feb 2000 Posts: 5,208 'Bolter | | 'Bolter Joined: Feb 2000 Posts: 5,208 | Easy way out, I don't believe GM ever used brass plugs. | | | | | Joined: Feb 2004 Posts: 29,780 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,780 | If you're really determined to have a shallow brass plug, make your own. Start out with a piece of flat brass stock about 3/32" thick, cut out a round disc slightly larger than the hole you want to fill, and use something like a 2" trailer hitch ball and a big socket to put some dish in it. Then file it to be a snug fit into the counterbore and tap it firmly into place.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
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| | | | | Joined: Jan 2015 Posts: 914 'Bolter | | 'Bolter Joined: Jan 2015 Posts: 914 | This thread is one of the many examples how this forum spreads knowledge. Jeffrey | | | | | Joined: Jul 2010 Posts: 592 Shop Shark | | Shop Shark Joined: Jul 2010 Posts: 592 | With a little more research, I discovered that Melling makes a 2" brass concave expansion plug. Part number MEP-26B. Summit Racing carries them, but only in bags of 10. $2.97 plus $5.95 shipping.
Matt | | |
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