455 Block oil system modifications and prep work
Background information
Should I modify my block?
In a word, Yes.
As we look into the oil system modification on the 455 block, it's important to remember that this engine was originally designed to move Grandma around in the Electra, with the engine operating in the idle-3000 rpm range. And for what it was designed for, it worked very well, it's not uncommon to get well over 100K on a stock motor. But, when we start asking more from the motor, we need to "help it out" with a little more oil to the bearings. That's the basis for modifying the block oil passages. The typical performance motor runs from idle to 6000 rpm and even if your building a "warmed up" stocker, the following mods can prove beneficial to your engine.
Our example motor is one from a frame off restoration that is in the shop here at TSP, and it's going to be far from a Drag strip screamer. It will be a very basic restoration type 455, right down to the NOS Stg 1 camshaft. But even this motor benefits from these mods.
When to modify?
This work should be done at the onset of a complete rebuild, as the first process after disassembly. If you eventually find that you have to replace the block, consider it good practice.
The piece in question
Here it is, in all it's 34 year old Glory. This is an original SS coded and vin number matching 1970 STG 1 engine. I picked this particular motor to use as our example for a very specific reason. Now, ask any 10 "in the know" Buick guys, and they will tell you that the STG 1 motor for 1970 was the only 455 of that year that had the 5/8 oil suction passage, the standard 455 had just a 1/2 suction passage. Unfortunately, this bit of trivia does not always hold true. I have in fact seen several 1970 STG 1 motors with that larger suction passage from the factory. But this is the second true STG 1 motor, of this vintage, that I have seen with a 1/2 suction passage, with the 5/8 pickup tube. I also chose this motor because this particular vintage needs the most modification.
And that small oil hole.. be very careful guys, when you start talking "absolutes" with anything that was built in a factory.
Ok, let's talk tools now.
Your going to need the following items to do everything we will discuss here.
5/8 Drill bits- 6" and 12"
1/2 Drill bits- 6" and 12"
11/32 Drill bits- 6" and 12"
12" Shank ball end carbide burs, 1/4" and 1/8"
3/8 and 1/8 NPT taps- and tap holders or sockets that fit the square drive shank of the tap.
1/2, 5/8, 3/4 counter bore bits
Good 1/2 inch corded drill
Air powered Die grinder
Compressed air and blow gun.
And the following parts:
TA Performance is the supplier for all the specialty parts we use at TSP. Their phone number is 480-922-6808.
TA 1519 Oil galley plugs
The TA 2060 drill bit kit will get you the 12" 1/2 and 5/8 drill bits. They supply a 17/32 for the main oil feed hole, but I prefer to use a 1/2 for this. I have broken thru a block casting drilling that hole any bigger than 1/2". Blocks do vary quite a bit, and I consider 1/2 to be 'safer' for that particular mod. More on that later.
The other bits and supplies can be found at a multitude of suppliers, from industrial supply hoses, machine tool supply houses, to Home improvement and hardware stores.
In addition to these tools and supplies, it's important that you get your hands on a good tapping/cutting oil. Available at most industrial supply stores, this will insure that you keep the drill bits sharp, will aid in tapping.
The modifications
Oil Pressure Feed Hole Modification
Main Bearing oil hole modification