I think that I saw a thread somewhere about installing a freeze plug in this hole instead of drilling and tapping it. Since the block already has the cam bearings installed, the only way I could drill and tap hole would be to turn the engine upside down on the stand and drill up to prevent shavings from entering the engine. Or should I just let the head gasket seal the hole? Jeff
That's how it should have been done before the cam bearings were installed. This is another operation that the engine builder overlooked. I don't want to risk getting metal shavings in the engine behind the front cam bearing.
I took an aluminum rod, made a 1/2" long dowel out of it, tapered one end enough to start in the hole and tapped it in with a punch and hammer to fill the hole. The slivers peeled off in big slices and were easily cleaned up. Seems to be working so far.
Jim has a post about it in the oil mods thread. Post #8, he taps it though. http://www.v8buick.com/index.php?threads/400-430-455-block-id-prep-and-oiling-mods.214613/
Thanks, I read that but I would have to do all of this laying on my back with the engine upside down to prevent shavings from falling down behind the #1 cam bearing.
The 350 has the hole also and is not needed. Read post #8 in 455 street/strip oil mods. Actually, the v6's must have it too. Back in the early 80's while working as a Buick technician, I did many head gaskets on the 3.0 liters in the Century's. I never understood how a head gasket could leak unpressurized return oil. Now I know!
Actually it's not a drainback hole. On the '70 & up big blocks at least, it's a leftover pain in the neck from the previous through-the-rocker shaft oiling strategy. Once they started oiling through the pushrods, the hole in the right bank was eliminated, but they were forced to keep it on the left because that drill spot was the only way to make things work in the front cam bearing. Devon
I know that now, but back then I didn't realize that it was there. I assumed that only return oil went through the head.
