`Buick 455 Oiling Modifications`

By Gary Fanning and Dave Knutsen

Photos by Gary Fanning

*** Please wear safety glasses for all these procedures. It's always a good idea to have a second pair of hands and eyes for guidance (and safety). Please feel free to check with Buick experts on the e-mail list for their particular methods on modifications and other tips.

These photos are of a '73 block on a stand upside down.. main bearing saddles up. Keep in mind that the '73 block has larger passages than earlier blocks so the pre-drilled measurements here are slightly larger. I used cobalt drill bits. They're quite expensive so titanium would be sufficient, but at least be sure to use new, sharp bits... and go SLOW, pull the bit back to clean shavings frequently. Use a shop vac to keep the journals clean and a gun bore light to view progress and results.

This one is #2 Main bearing to cam bearing. I was told all but the #1 journal were 1/4" and #1 was 3/8" but on the '73 block here the #1 was 7/16" and the rest were 5/16". All this means is that I took out 1/16" instead of 1/8". The same size drill bits can be used for all blocks. You can see the #3 on the left side and the 5/16" hole. #1 main bearing journal I did nothing. #2 - #5 I drilled from 5/16" to 23/64". The 23/64" saves a little more metal in the cam bearing saddle than a 3/8" bit would but still allows increased oil flow. Drill this all the way through to the cam bearing saddle and into the main lifter galley. After this modification, you definately need to use the fully grooved cam bearings, not because of the full groove, but rather because they are wider than the stock #2,3,4,5 bearings and will seal up the oil passage from the now larger slot going through the cam journal.

The #5 main bearing saddle to cam bearing seat I took out to 3/8". There is lots more meat in this saddle so it seems less stressful. Notice the journal hump below the drill bit. This is the path the bit must follow. Be especially careful on your left/right alignment so you don't go through this area.

I drilled the main oil passage from the send unit to the #1 cam bearing seat, being especially careful to stop short of the cam bearing seat. I drilled to 7/16" first and followed with 1/2" bit ($25 EACH). I used a 'bore light' that I picked up at a gun shop.. works great. I could easily see the progress of the drill bit. The white tape is extra precaution.. measured to max depth I wanted to go before reaching the cam seat. Also, placed a shop vacuum on the hole to this journal to keep shavings out of the drill and journal. This is another area where left/right allignment is critical. I've heard of cases where the drill bit has gone astray and punched through the block. It can be fixed but extra caution will help you avoid that sick feeling. Use a 3/8" NPT tap to re-thread for your send unit. Then simply buy a 3/8" NPT fitting to adapt to your particular send unit thread size, usually 1/4".

The journal from the #1 Main saddle also intersects with these and can be drilled to 3/8" on some of the older blocks but the '73 was already 7/16".. no action required.

That is a 12" Titanium or Cobalt drill bit and required a 1/2" drive electric drill. Be careful here; the bit really can take off through the block. Go SLOW to avoid binding of the bit.. especially with the 1/2" drill.. it will take your arm off if it binds.

The timing cover main passage can be enlarged to either 1/2" or 9/16". The Dove book recommends 9/16". This is a 1/2" bit. I might move to the 9/16" after further inspection. Depending on who you talk to it may or not be recommended to drill the passenger side lifter galley through to enlarge it. It tapers about halfway back. I decided not to do it even though I have no plans for a roller cam. According to TA Performance, "One of the big problems with drilling it all the way is that when running a roller cam, the roller on the lifter becomes exposed into that oil gallery. Then there will be a loss of oil pressure. On flat tappet cams it's not that big a deal."