High-performance Oiling Systems
Do you have a high-performance oiling system. You will if you follow these tips from our Tech Insider.
Words: Larry Shepard
If asked to consider an engine’s oiling system, most performance enthusiasts would probably point to the oil pan or oil pump, both of which reside on the bottom part of the engine. At the very best, engine oiling tends to be one of the last items considered during an engine build-up, perhaps because it is on the bottom, and one of the last systems to be installed. However, the engine’s oiling is much more complicated than we might think and very important.
Because of this overall complexity, I’ll limit the discussion to our older V8 engines, the A-engine, the B/RB-engine and the 426 HEMI.® Additionally, the typical cylinder block like P5007552AB (340 replacement) has many oiling passages machined into it. A crank like P5007257 (3.58" stroke for 318/340 mains) also has oiling passages and cylinder heads like P4529993 (Stage V B/RB cast iron) has oiling passages that come up from the block and oil return considerations for the oil to get back to the pan. These block, crank and head concerns are beyond the scope of this article but are covered in detail in performance books like the A-engine (318-340-360) book P5155062. Note: The Magnum V8 (5.2L & 5.9L) engines are discussed in their own performance book P5153770.
The number one job of the engine’s oiling system is to keep oil in all the bearings. A bearing surface is actually any location in the engine that has relative motion between two parts, like rods, rings, rocker arms, crank, pushrods, pistons and pins. Another aspect of the oiling system is windage and its affect on engine performance. For the oiling system to do its jobs, it must circulate oil in a continuous cycle. This cycle creates an engine oil path which is discussed in the technical books mentioned above. The oil path touches virtually every part in an engine. In general, there are two styles of oiling systems, one that collects/stores the oil on the engine (wet sump) and one that collects/stores the oil remotely (dry sump). I will limit this discussion to wet sumps because production engines use wet sumps.
So let’s start our discussion with the engine’s oil pan. Typically each engine family has a unique oil pan, but it is more complicated than that. For example, on the 360 A-engine there is a rear-sump pan P5249060 and a center sump pan P5249059. The 318 and 340 versions use pans with large front/rear radius. The rear sump pans work best in trucks and the center-sump pans are used in passenger cars (large vans use a front sump pan but these are not popular in high-performance applications).
Custom applications typically use the rear sump versions, with the center-sump versions as the back-up option. The big blocks which include 383s, 440s and 426 HEMIs use a pan with a flat attaching rail such as P5007807AB, which is a 5-quart, center-sump design. It is common in performance applications to increase the sump’s capacity. This is commonly done by dropping the bottom of the sump one or two inches, which increases the capacity by one or two quarts. The trade-off and caution is ground clearance. As the sump’s bottom is dropped, ground clearance is decreased and can become a problem. Drag race only cars have more flexibility on the ground clearance issue, but on true street cars this can be a major concern. A performance trick is to add a baffle across the rear of the sump, if the pan that you have does not have a rear baffle.
The heart of the oiling system is the oil pump. The A-engine pump is located at the rear, on the #5 main cap and inside the pan. The high-performance A-engine pump is P4286589. The similar B/RB/HEMI pump is P4286590 and is located on the left-front of the block on the outside. To connect the oil pump or block to the oil collected in the pan’s sump, you need a pickup like P4529563 for the center-sump A-engine pans. The B/RB/HEMI blocks can have a 3/8" pipe or 1/2" pipe pickup plus the added complexity of sump location and depth. Added together you have quite a selection. The pickup should be selected based on the pan being used. On the wedge (383 and 440) production blocks, I would recommend upgrading the standard 3/8" pipe attaching hole to the 1/2" pipe hole and changing the pickup to match the new hole size and your pan.
While the observed oil pressure tends to be a function of the engine’s bearing clearances and the oil’s viscosity, there is an oil pressure relief spring located inside the oil pump itself that can be changed to increase the pump output or pressure. On the big-block pumps, this spring is P4286571, while the A-engine high-pressure spring is P3690944. The oil pressure guideline is 10 psi per 1,000 rpm for minimum pressure. I no longer recommend rebuilding used oil pumps. The quality parts are hard to find, and new pumps are readily available. There are many oil filters available like the red, white and blue resto filter P4529187 or the black race filter P4529190. Use caution with cold engines and thick oil (high viscosity): If the start-up oil pressure is near 100 psi, hold the engine rpm down as low as possible until the oil has warmed up or you may burst the can on the filter.
The oil pump pumps the oil into passages in the block and from there to the crank, cam, tappets and up to the heads. The rocker arms, valve stems, pushrod ends and valve tips must all be oiled. After its initial journey, the oil runs down the head to return to the pan and complete its trip. The V8 heads sit on the block at a 45-degree angle so this gravity return isn’t as easy as you may think. Production heads cause no concerns because this feature was designed in, but race heads with big ports can be a challenge. Remember that the production 426 HEMI head is so wide, that the oil returns are on the outside edge of the head at the front and rear of the head. To make this work there is a matching hole on each end of the HEMI block to allow the oil to return to the pan/crankcase. It is always a good idea to make sure these holes are open, in the head and the block. On the wedge engines the oil returning from the valve train ends up in the tappet chamber and drops through the holes in the center between the two rows of tappets. These holes must be open, not sealed, or no oil will return to the pan. The exception is on a dry sump system when a pickup is added to the tappet chamber. As the oil drops down from the tappet area and past the cam, it falls onto the spinning crank/rod assembly and will be thrown against the crankcase wall or the pan. Once on the crankcase wall, gravity will lead it to the pan and the pan will collect it into the sump for the next round trip.
There are many special oil considerations like the right-angle oil filter adapter P5249624AB for A-engines that allows the filter to be moved for header clearance. The B/RB/HEMI fully-skirted blocks use a special rear main seal retainer P4529732, which has two unique side seals. The production part was made of cast aluminum and the new part is billet aluminum for added strength and accuracy. The actual rear main seal was originally a rope seal, but the newer version P4271961 is made of rubber (neoprene). Be sure to point the lip at the #3 main. Typically the intake manifold seals the tappet chamber. On 383 and 440 engines, the intake gasket, called a breast plate, is made of stamped-steel and keeps hot oil off the bottom of the manifold. The 426 HEMI uses a heat shield (P4529431) that attaches to the bottom of the manifold to keep the oil off the manifold. If you are building a street engine, you must use valve seals. The key to that is to use the high-performance single-valve spring, which allows you to use umbrella seals like P4120492 (3/8" stem and Viton material). If you are forced into dual spring use, then you will have to install the special PC-seals P3690963 (3/8" stem). Once assembled, you will need a dipstick and tube (P4349628 A-engine or P4349629 big block); both are chrome. Remember that if you drop the pan’s sump or use a custom pan, you should re-calibrate the dipstick.
The oil’s viscosity (such as SAE 10W-30) and the oil’s basic make-up (such as synthetic) are important aspects, but beyond the scope of this article. One important issue is camshaft break-in and scuffing issues, especially relating to mechanical or flat-tappet cams. This relates to the zinc components in the basic oil and the use of diesel oil to solve them.
Another tricky topic is the intermediate shaft or oil pump/distributor drive. The hex-end of the shaft fits into the oil pump and the upper end is driven by the cam through a gear on the top end of the shaft. If you use a roller cam, either mechanical roller or hydraulic roller design, then you must use a new intermediate shaft that has an aluminum-bronze gear like P3690875 (all big block). The aluminum-bronze gear is a gold or yellow color while the standard ones are black or dark grey.
That leaves the windage tray. With all the oil that drains back over the rotating crank and rods and the oil that normally seeps out of the main and rod bearings, cam bearings and 16 tappet bores, the crank drags through this returning oil and creates windage. Windage affects the engine performance as a loss, so you want to try to decrease these losses as much as possible. A windage tray helps to do this. The A-engine tray P4529790 mounts to the main cap screws (kit P3690939). The same tray can be used on the 318, 340 and 360 versions. It is best used in road racing or street applications. The B/RB/426 HEMI windage tray installs between the bottom of the block and the pan using two pan gaskets P4452099 (set of 2). On the standard 440 engine, the 3.75" or shorter stroke cranks, the tray P4120998 is worth about 15 horsepower. No other changes are required. This tray does not work with the longer strokes. For the 4.15" stroke cranks, use tray P5007345. The horsepower gain is over 25. The extra gain is caused by the increased windage on the longer stroke so don’t install this tray on the 3.75" engines (it fits but doesn’t offer the big horsepower gain).
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