Oil Suction Hole enlargement
Most 1971 and later 455's have a 5/8 oil suction hole in the block from the factory. Early 400/430's and some '70 455's have a 1/2 hole, which needs to be enlarged to 5/8, and a 5/8 pickup tube should be used. The big pickup is available from TA Performance, Part number TA 1520A, and can be used on all 400/430/455 engines.
Hand in hand with this modification, goes the need to replace your "small" timing cover with a later vintage or a new TA timing cover. The bigger cover is easily identified, by the 12* timing tab, the earlier cover has an 8* timing tab on it.
We will cover the timing cover in depth on it's own page.
Using your short 5/8 drill bit, start the hole carefully.. you need to keep the hole centered with the original hole. Use the cutting oil here also. I don't recommend you start with the 12" bit, as it is much harder to keep it nice and straight.
This is as good a time as any to discuss the drill. You need to have a powerful, corded 1/2 drill, like this Milwaukee Magnum. This drill comes with a handle that screws in the side, and it's not on the drill for a reason. In drilling cast iron, when you start the holes, and intersect other holes that exist in the block, the drill will catch and want to snap out of you hands. You want it to do this. Using the handle will let you keep the drill in your hands, but will also increase the chance of breaking the drill bit in the block.. and that will ruin your day.. We will also discuss a tip on drilling and intersecting existing holes as we go along here.
All set up with the short 5/8 drill bit. Time to start drilling!.. Use oil, and start the hole straight!
Continue to drill, until your out of room with the 6" bit. Drill slowly and carefully, making sure to keep the hole centered. Then finish with the 12" bit.. it will take nearly all the bit to drill it all the way. Look down the pickup oil hole with a flashlight, and make sure your all the way thru.
It's going to go this far with the 12" bit.
Now you have to drill out the hole to the pickup tube.
Do this with your 6" 5/8 bit, and point it at the hole in the block, cheating a little to the outside of the block.
You cheat to the outside of the block, because the hole you just drilled intersects this hole low, so cheating the pickup hole to the outside ensures your going to break into the main part of the suction hole.
Now your going to come into your first experience with intersecting an existing hole. And yes, the drill did just get jerked out of your hands! This happens when the drill bit breaks a portion of the hole open, but leaves and "edge" which the flute of the bit grabs, and stops the bit dead. Look down the hole with your flashlight, and you will see what I mean.. instead of drilling this out, and fighting not to break my wrists or the bit, I simply chuck up my 1/2 round carbide burr in the die grinder, and then grind out the rest of the hole, making a nice radius where the holes intersects while I am at it.
Drill it this far..
And then work it with your die grinder and carbide bur, till it looks like this. chamfer the hole slightly where the pickup bolts on, and your all done.
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