Buick Oiling Improvements
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Stuff you can do to improve oiling on your Buick 400, 430, or 455. These concepts apply to other Buick V8 engines as well - 300, 340, 350 - though the exact details may differ.

There is some info about these types of modifications on the Buick Performance site, as well as a good bit of detail in the book Guide to Buick High Performance Engines by Steven L. Dove. I bought my copy of the book through either Poston or TA Performance a long, long time ago. You can also try Amazon.

Note that unless called out otherwise in the text, these picture were taken with the engine upside down on the stand. This means that top/bottom and left/right are reversed from the "in car" mounting, so don't get confused by that. The first pictures I saw of this were very close up and labeled from the "in car" perspective even though the photos were taken with the engine upside down on a stand. It was all very confusing to me until I got in the garage with the engine and the drill bits, so I thought I'd mention it here for folks contemplating doing this sort of things for the first time. Old timers may snicker at this little reminder, but we were all new to this stuff once. When this is new to you it is very mysterious, confusing, and quite scary to contemplate taking power tools and carving up parts of your very expensive - and likely the only one you have around - engine block. One of my goals in posting this page is to do a better job explaining it than I've seen done elsewhere, and in doing that to help others feel comfortable making these changes to their own engines.

 

Drill Bits and Drilling

You need a longer-than-normal drill bit to do some of this work. TA Performance sells a number of long-shank drill bits that can be used for this task, but not a 7/16" bit. I ended up buying 12" long 7/16", 1/2", and 9/16" drill bits along with a rebuild kit from PAE Enterprises, and they were very reasonably priced. What I spoke to Jim at PAE about my rebuild kit, I mentioned the need for a 7/16" drill bit that was 12" long, and he said he has a source for these drill bits locally and would be happy to sell them to me for a small markup over his cost. I would assume they need to use them in their in-house machine shop work on customer's engines, so they already know where to find them. I'm just happy to have gotten the right drill bits. Shown below in the first picture are the 7/16" and 1/2" bits I received from PAE Enterprises. I also later got a 9/16" bit to use on the oil suction passage - that's the second picture.

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For the drilling operations noted here, a 1/2" chuck drill is pretty much mandatory - both to be able to put the bits in the chuck and to have enough power to do the job. As you do this work, you will be drilling into the engine block with a fairly large drill bit using a pretty powerful drill. This sort of work requires some care - if the bit jams, the drill will suddenly rotate and can injure you and break things in the process. Use some kind of cutting oil when drilling, get the bit up to speed before you enter the material, go slow, and frequently back up to clear any metal chips. Once the drill starts going, it can drill deeper very quickly in some cases - especially if you are only drilling out a mere 1/16" of metal such as when enlarging the main oil feed from 3/8" to 7/16". This means you can't just lean on the drill willy-nilly - keep the drill steady and do the drilling as a smooth, well-controlled operation.

 

Cam Bearings/Journals and Drivers Side Valvetrain Oiling

This is a big topic for the Buick 400/430/455 engines - all oil pressure for the drivers side lifters, pushrods, and rockers flows through the front cam bearing. If that cam bearing starts to "melt out" and plugs the oil feed hole to the drivers side of the motor (the first thing to plug up, typically), you start to lose oil pressure on the drivers side of the motor with predictably expensive results. There are three basic solutions that are presently known:

  •  Install heavy-duty grooved cam bearings. PAE Enterprises, Poston, and TA Performance all sell these and they are strongly recommended for any rebuild.
  •  Groove the cam journals in the block. There is no kit for this - this is strictly a "do it yourself" machining operation.
  •  Install a "bypass line" between the two plugs for these oil passages at the back of the engine. Poston sells a kit for this and it can be installed with the engine in the car if needed, though you do have to remove the transmission.

The heavy-duty grooved cam bearings are the easiest and best solution if you are already doing a rebuild. Just install the new heavy-duty grooved cam bearings in the "preferred" positions as noted in the next section, and you're good to go. This improves both cam bearing oiling and the drivers side valvetrain oiling - and it requires no extra machine work.

Grooving the cam journals in the block used to be the recommended approach before the grooved cam bearings were readily available. As the heavy-duty grooved cam bearings are readily available now for a very reasonable cost, this is no longer the recommended procedure. It does work, but it is a pain to do and hand-machining something as important as the cam journals in your block is, IMHO, a bit of a risky proposition for most folks. If you choose to do this, the procedure is to create a groove in each of the cam journals that is approx 1/8" wide by approx 1/16"-1/8" deep. For the front cam journal, you need to groove it from the 9 o'clock passengers side oil hole, counterclockwise (across the bottom of the cam journal), and up past the drivers side oil hole at the 3 o'clock position to around the 1 o'clock position. (You can also simply groove the front came journal a full 360 degrees - the minimum work gets you about 3/4 of the way there already and more oil flow is a good thing here.) The remaining cam journals need to be grooved from the 9 o'clock passengers side oil feed hole counterclockwise (across the bottom of the cam journals) to about the 4 o'clock position. This is to allow the groove to meet up with the oil holes when the cam bearings are installed in the "preferred" positions noted in the next section.

The bypass line is a "quick fix" you can apply to the engine with it still in the car to improve the driver side valvetrain oiling. You have to drop the transmission and remove the flywheel/flexplate to get at the rear oil passage plugs to do this, but it's cheap (about $15 for the kit) and it helps stave off a rebuild for a while longer on a stock engine. Note that this does not help with cam bearing oiling and should not be considered for any engine that is being rebuilt.

 

Cam Bearing Installation

If you are using the heavy-duty grooved cam bearings or you have grooved the cam journals in the block, it is highly recommended that you install the #1 (front) cam bearing so that the holes are at the 6 o'clock and 1 o'clock positions, and install the remaining bearings so that the hole are at the 4 o'clock position. The front cam bearing is the only one with two holes in it - don't mix them up! Keep in mind that if you are opting to groove the cam journals, the only reason to groove anything other than the front cam journal in the block is to install the bearings this way.

The original Buick-specified orientation is to match the cam bearing holes to the oil feed holes in the block. This puts the #1 (front) cam bearing with the holes at the 9 o'clock (oil in from the passengers side main oil gallery) and 3 o'clock (oil out to the drivers side valvetrain oil gallery) positions, and puts the remaining cam bearings with the hole at the 9 o'clock position. These are not optimal positions for oiling a clockwise rotating camshaft - the main pressure point is on the bottom of the camshaft (the 4 o'clock to 7 o'clock area) as the lifters push down on it (via forces transmitted down through the rockers and pushrod from the valve springs). If you oil the bearings from the 9 o'clock position, the oil pressure bleeds off as it travels around the nearly 3/4 of the rotation is takes to get the oil around to the main load area at the bottom of the cam bearing. This is particularly true of the #1 (front) cam journal which sees the highest loads from the timing chain and the distributor gear pushing on it - and it has the added burden of being designed to bleed off pressure at the 3 o'clock position to pressurize the drivers side valvetrain. That leaves very little oil pressure left at the 4 o'clock position to actually oil the bearing.

All clock positions are observed from the front of the engine with the engine in an upright position. If you are working on an engine stand with the engine upside down, your clock positions will be 180 degrees off from "up", so pay attention to what you are doing here! The diagram below should help make it clearer.

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Main Bearing Oil Feed Holes

I opened up the oil passages leading to the main bearings to ensure full-flow to the mains. It's common for Buick 400/430/455 engines to have slightly mis-aligned passages. Sitting the old bearings in the block revealed which ones needed to be opened up, and in what directions

Keep in mind that the idea here is just to ensure full flow to the bearings, not open up the entire oil passage - thus the limited depth of the drilling. Personally, I didn't want to risk going sideways and punching a hole in the main webbing and ruining the block for a questionable addition in flow for a street motor. If you are running fully grooved main bearings and your motor is going to see more "heavy duty" use, then you can go ahead and open up the main oil passages all the way through to the cam journals. If you want to do this, beware of going through the side of the block and be aware that you are removing "meat" from the main bearing supports. If you do drill all the way through, you also need to make sure that the cam bearings adequately cover the enlarged holes. I've read (but not verified) that the stock cam bearings do not adequately cover the enlarged holes, and that the grooved/heavy duty bearings are wider and thus do cover them adequately.

For final cleanup, the drill bit left a small raised ridge of metal in the main bearing saddles that would have caused the bearings to not seat right, so a few minutes with a round file ensured all was well there. I used the file to both flatten the riser and to file a very tiny chamfer around the edges of the drilled holes. Basically, I wanted to ensure there were no remaining sharp edges that could cause the main bearings to "pinch" the crankshaft.

These pictures show the slight mis-alignment that is common in the main bearing oil feed passages.

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To fix this, I just drilled in about 1/2" with a 3/8" drill bit to get most of it right, and hogged the drill bit sideways on a few of them to get it the rest of the way. The oil passage on the #1 bearing is bigger than 3/8" from the factory - 7/16" on the 1969 430 block I took these pictures on, so that one was purely a matter of pushing the bit sideways just enough to get the needed clearance. In this overall picture of the bottom end, you can clearly see the oblong shape I created on the #1, #2, and #5 bearing oil holes.

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This picture is a close-up of the #1 bearing oil hole.

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These pictures are close ups of the #3 and #4 main bearing oil feed holes that clearly show the "step" in the oil passage where I stopped drilling.

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Main Oil Feed Passage

The main oil feed passage that runs from the oil pressure sender hole all the way up to the passenger's side main oil gallery is usually only a 3/8" passage. The passenger's side main oil gallery is very important as it feeds the main bearings, cam bearings, and the passenger's side lifters, pushrods, and rocker arms. If you drill it out to 7/16" you will vastly improve the volume of oil that it can flow to the entire engine - and you will not need to re-tap the oil pressure sender threads to a larger size. This size should be adequate for street use. If you have "heavier duty" usage in mine, you may wish to go to 1/2" or even 9/16". If you go any larger than 7/16", just remember to tap the oil pressure sending hole for larger size threads and then get the right adaptor to install the oil pressure sender.

When enlarging this passage, you want to be sure that stop your drilling before you intersect the front cam bearing journal so that you don't end up with a gaping hole in the cam bearing journal that the cam bearing may not cover. You only want to enlarge the oil feed to the main oil gallery in the passenger's side of the motor. The feed for main bearing #1 intersects the passenger's side main oil gallery at the same place as the feed from the oil pressure sender hole, so use the main bearing #1 feed as your sight hole if you need to check depth. You can follow the path of each passage to understand where they intersect inside the motor.

Check the feed hole from the front of the block to the oil pressure sender as well while you're here. It should already be at least as big as the main oil feed to the camshaft, but verify and make sure, especially if you are drilling the feed hole from the oil pressure sender larger than 7/16". It is a very short passage and easy to enlarge if needed.

You need a longer-than-normal drill bit to do this - most drill bits come up a very frustrating ~1/4" too short. TA Performance sells long-shank 12" drill bits that can be used for this task. PAE Enterprises can also get the required drill bits if you ask them about it. See above for pictures of the drill bits themselves.

This picture showing the two intersecting oil passages that matter here. The drill bit sticking out of the top is sitting in the front camshaft bearing to #1 main bearing oil feed passage. The drill bit sticking out to the right is bit is sitting in the oil pressure sender to front camshaft bearing feed hole. Connect the dots to follow the oil passages.

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These pictures show a close-up of the front cam bearing oil feed hole. In the first picture, you can clearly see the end of the drill bit in the opening. This shows how the oil passage was originally drilled down from the #1 main bearing to slightly intersect with the front cam bearing surface and create an oval-shaped opening for the oil to flow through. The factory was pretty darned clever about not machining any more than they had to, and precision drilling operations cost time and money, so they did as few as possible.

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Here's the 7/16" bit in my 1/2" chuck drill with a piece of tape to tell me when to stop drilling and start paying real close attention to how deep I was drilling. As noted above, the idea is to intersect with the oil passage that comes down from the #1 main bearing without drilling the surface of the cam bearing out. I just held the bit up next to the engine along the intended path and got a good guess on the length, being somewhat conservative so I did not drill too deeply. Note that if you only go to a 7/16" bit, drilling too deeply is not a huge deal, but if you go to 1/2" or even 9/16" hole, going to deep could be a very costly mistake if your cam bearings do not cover the wider opening once they are installed.

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Here's the drill and bit at full depth in the main oil passage. Note the location of the tape on the drill bit in relation to the block. You can also see the drill bit in the main oil feed hole in the front of the block. This is where oil enters from the front cover and heads into the engine.

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These show the end of the drill bit where I stopped drilling. Close observers will note that yes, I did slip and drill a bit too deeply. The front cam bearing should cover the slightly widened hole since I only used a 7/16" drill bit.

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Oil Suction Passage in Block

The stock passage on 1967-1970 400/430/455 engines is only 1/2" in diameter. Starting in 1971, Buick enlarged this to 9/16". If you have a 1967-1970 block, you may want to drill this passage out to 9/16" to provide more oil flow to the system. At the very least you want to run a 1/2" drill bit down the length of the passage to ensure there are no restrictions in it.

You need a longer-than-normal drill bit to do this. TA Performance sells long-shank 12" drill bits that can be used for this task. PAE Enterprises can also get the required drill bits if you ask them about it. See above for pictures of the drill bits themselves. In my case I only had a 1/2" bit when the pictures were first taken, but the details are clear enough. The last set of pictures are the only ones taken after the 9/16" drill bit came in and I did the actual drilling.

These pictures show the drill bit laying along the side of the block right over where the oil suction passage is. They show approximately how deep you have to drill on this passage and why a 12" long drill bit is required to do this work.

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These pictures show the drill bit in the oil passage to the final depth.

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These pictures show the drill bit in the short connector passage that goes from the oil pump pickup mounting to the main oil suction passage. It is angled and intersects the passage in the block offset and at an angle. Be careful when starting the drill here and don't go too deep and punch a hole in the block.

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Here's the actual drilling results with the 9/16" drill bit. If you look closely in the second picture you can see where I intersected the short passage into "top" of the long passage.

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Oil Pickup Tube

Similar to the oil suction passage in the block, 1967-1970 400/430/455 engines used a 1/2" diameter oil pickup tube. Starting in 1971, Buick enlarged this to 5/8". You should use the later-style 5/8" pickup tube on any rebuild you do. TA Performance sells these new if you do not have any extra 1971-1976 455 pieces laying around to use.

Remember that the pickup tube must match your oil pan, so if swapping pans and pickups around, double check that everything is in the right place before you bolt the pan onto the block. It must be down close to the bottom of the oil pan to pick up oil and stay submerged at all times.

 

Oil Pump Idler Gear

Make sure that your oil pump idler gear (the one that is not driven directly by the distributor) has a small (~1/8") hole in the bottom of one of the gear valleys. You want to make sure the post that this gear spins around receives good oil pressure to prevent the gear from galling the shaft or worse, seizing on the shaft at an inopportune time. Some may already have it, some may not. Check yours and be sure, and add it if needed.

Here are the gears I removed from my 1969 430 when tearing it down for a rebuild. If you look carefully, you will see that the idler gear (on top in the photo) has the 1/8" oiling hole in it.

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Here are the new gears from the rebuild kit I purchased. The idler gear does not have the 1/8" oiling hole in it.

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Here is the new oiling hole. The first picture shows it being started, and the last two show it completed.

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Oil Pump Booster Plate

These are a simple addition to your oil pump that is carried by PAE Enterprises, Poston, and TA Performance. It is a steel plate that fits between the oil pump and the oil pump housing. It provides a much more solid thrust surface for the oil pump gears to ride against - the steel gears normally ride against the aluminum housing and can easily cause scoring if anything less than perfectly clean oil is circulating through the engine. Adding this provides longevity improvements, plus a small (but important) boost in oil pressure.

NOTE: If you have enlarged the oil passages in the oil pump and booster plate, make sure you enlarge the oil passages in the booster plate and the gaskets to match. A chain is only as strong as it's weakest link, and an oil passage is restricted by it's narrowest point - even if it's only a section as long as a gasket is thick.

These pictures show the booster plate sitting on top of the oil pump cover so you can get an idea of how it's supposed to sit there.

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These pictures show the slot and how I enlarged it to align with the original opening in the oil pump cover. The first two pictures are before my modification and the last one is after my modification. Look carefully at the upper left and lower right corners to see the how I enlarged the slot to make it slightly larger than the hole in the oil pump cover.

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These pictures show the round hole at the top and how I enlarged it to align with the original opening in the oil pump cover. The first three pictures are before my modification and the last one is after my modification. Look carefully at the lower left area of the round hole to see how I enlarged it to make it slightly larger than the hole in the oil pump cover.

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Oil Passages in Front Cover

The stock oil passages in the front cover are only 3/8" in diameter in some places. Drilling them out to 1/2" or even 9/16" diameter allows for improved oil flow into and out of the oil pump, and thus improved oil flow to the rest of the engine.

NOTE: If you have enlarged the oil passages in the front cover, make sure you enlarge the oil passages in the booster plate and the gaskets to match. A chain is only as strong as it's weakest link, and an oil passage is restricted by it's narrowest point - even if it's only a section as long as a gasket is thick.

 

Oil Passages in Oil Pump Cover/Oil Filter Mounting Pad

It's unclear to me if the oil pump cover/oil filter mounting pad should also be modified with larger passages. Some folks say it helps, others say it's not worth much so don't bother. Clearances seem tight with not much meat in the cover to grind away at, and some of the holes are rather odd shaped - like the square slot - and hard to open up evenly. At the time this was written and I was working on rebuilding a 1969 430, I opted to open up the passages in the front cover and the booster plate, and stop without touching the oil pump cover/oil filter mounting pad.

NOTE: If you have enlarged the oil passages in the oil pump cover/oil filter mounting pad, make sure you enlarge the oil passages in the booster plate and the gaskets to match. A chain is only as strong as it's weakest link, and an oil passage is restricted by it's narrowest point - even if it's only a section as long as a gasket is thick.

 

Adjustable Oil Pressure Bypass Spring

TA Performance sells a kit to make the oil pressure bypass spring pressure externally adjustable - it's TA1502. It's highly recommended to allow you to adjust the maximum oil pressure without disassembling the oil pump. It's much less messy than swapping springs, and much faster too.

 

High Volume Oil Pump

These use longer than stock gears and a oil pump extension housing for more oil volume. They are not needed for most street/strip use and are only recommended for some extreme-duty situations. They often cause other issues; if you are considering using one, you should consult an experienced Buick rebuilder to determine if this is right for you. Folks usually recommend against these nowadays, and in most cases, even for some pretty serious track use, they are not needed or desired.

If you do decide to do this, make sure you add the distributor gear oiler.

 

Distributor Gear Oiler

This adds a small stream of oil directed at the distributor gear and is only really needed if you use a high volume oil pump. PAE Enterprises sells a kit for this. It can't hurt to add it to any installation, but it is not required unless you use the high volume oil pump.

 


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Page last updated 01/02/2009 01:51:39 PM