The oiling system isn’t as high profile or glamorous as heads, cams, and other parts. But as we all know, it plays a vital role in the performance and longevity of an engine. The oiling system touches all of those parts. Clearance is an issue for street cars and street/strip vehicles, so you have to make sure that the oil pan can’t hit the ground. Also, make sure that the pan fits in the engine compartment, clearing the headers and steering linkage.
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Although it may not be one of the leading topics at a bench-racing session, if the oiling system fails, you will have a catastrophic engine failure, which is very expensive. You need to bring the oiling system along as you develop power: improve the head, improve the oiling. When building a max-performance engine, you should upgrade the oiling system. Your first priority is to install a higher-capacity oil pan and a wet-sump oil pump for higher pressure and/or volume. The next priority is to add baffles to the pan (sump area) to control the oil.
A-engines and Magnum engines use very similar oiling systems, especially in the short block. Valvetrain oiling, however, is different. The A-engine oils through drilled passages in the block and heads to the valvetrain; the Magnum oils the valvetrain through the pushrods.
The oiling system is actually involved with every part in the engine assembly. Many of the paths that the oil takes from one part to another are in the block and the crank. The oil also lubricates the cam, tappets, valves, rocker arms, pistons, rods. Rocker arms and valve tips are the most difficult parts to properly lubricate. Oil galleys drilled into the block move the oil from the pump to the bearings and other parts needing lubrication. These drilled passages must be plugged to direct the oil where it is needed.
The camshaft propels the oil pump drive, and that drives the oil pump. The oil pump puts out oil pressure and flow volume based on engine speed, low at idle and high at higher RPM. As a general guideline for oiling systems, you want the oil pump to deliver 10 psi per 1,000 rpm. Any internal oil leak(s) drops this number or makes it more difficult to obtain. Therefore, trying to control internal oil leaks is one of the key aspects of the oiling system but has little to do directly with the oiling system parts.
One of the first items to address is bearing clearances. Try to use new parts to get the bearing clearances back to the original numbers, which is especially true of the thrust bearing (number-3). Stock clearances are fine, but you don’t want ones with .002 or .003 extra because you can’t get any oil pressure with them. The next internal oil leak is the rod side clearance. There are four of them. The specification is .006 to .014 inch. In used engines, it could be as high as .020 inch. On a new engine, you want it on the close side (.006 to .010 inch), not on the high side (.012 to .014 inch or higher). On the A-engine, do not restrict the oil to the heads or valvetrain. On the Magnum, the hydraulic tappet is installed with the oil hole away from the block wall (toward the center). (See Chapter 4.)
The small-block oil pump sits inside the oil pan at the rear on the number-5 main cap. The oil pick-up threads directly into the oil pump housing. Both high-volume and high-pressure oil pumps are readily available for the Mopar small-block (Melling). I recommend upgrading to a high-volume pump if you are replacing the heads and cam.
To increase the volume of the stock-style oil pump, the rotors inside the pump are increased in thickness, which means that the pump pushes out more oil at the same engine speed. To accomplish this thick-rotor pump, both pump rotors and the cover are replaced. Kits for this conversion are no longer available. When building a high-performance street engine, always install a new oil pump.
Production small-block oil pumps are Gerotor designs (also spelled Ge-rotor) with four inner lobes and fi ve outer lobes. Gerotor-style pumps are very effi cient. Small-block pumps use a wide, rounded rotor lobe design; Milodon (performance oil pumps with Gerotor design) uses a similar four/fi ve inner/outer rotor design but the lobes resemble a pyramid. (The name Gerotor stands for generated rotor.)
The universal guideline for oil pump pressure is 10 psi per 1,000 rpm. The typical stock pump probably puts out about 50 psi. The high-pressure relief spring is maybe 30 percent higher. Do not remove the oil pressure relief spring unless you have a new one and the press-in retainer cup in case the original is damaged during removal or use. Oil viscosity has an effect on oil pressure. Engine/bearing clearances also have an effect on oil pressure; close clearances help, wide clearances hurt.
The production small-block oil pump provides adequate performance for street use if it is not worn-out or damaged. The clearance between the outer rotor and the oil pump’s main housing should be less than .014 inch. The clearance between the inner rotor’s lobes and the outer rotor at the tip should be less than .010 inch. With the cover off, the clearance between a steel straightedge placed across the face and the rotors should be less than .004 inch. The pump must turn freely once assembled. If it passes these tests, it can be reinstalled.
The oil pick-up threads into the main pump housing of the oil pump, but where the inlet sits (the other end of the pick-up) is a function of the oil pan and the pan’s sump location and depth. If you install a pan with a dropped sump (Milodon or Moroso), you must install a new pick-up from same manufacturer.
If you switch the sump location, you must have a new pick-up. The inlet for the oil pick-up should be just above the bottom of the pan/ sump and toward the center/rear wall of the sump (passenger-side rear wall in a drag engine). Do not hand fabricate your oil pick-up; buy from oil system manufacturers such as Milodon or Moroso.
Breathers and the PCV
The breathers and the PCV (positive crankcase ventilation) valve are mounted in the valvecover (one on the driver’s side and one on the passenger’s side, typically) but should be considered part of the oiling system. Breathers and the PCV valve have been used with all production engines since the late 1960s.
The basic circulation system uses the breather in the valvecover to collect the exhaust gases that are in the valvecovers and the crankcase and returns them to the air cleaner. The PCV valve is designed to function with the breather (usually mounted on opposite valvecover). The PCV valve opens when there is a positive pressure in the crankcase, which indicates blow-by, and blow-by is not desired in any performance engine.
Adding oil to the engine is probably the last thing that you do in the engine assembly process; if you forget this step, you could be in some serious trouble. Because it is done last, you may not give the oil selection as much thought as you should. Today the oil replacement cycle (miles between oil changes) has increased from about 3,000 miles to 5,000 or even 10,000. Oils are better and engines are better. The last Magnum engine in 2002–2003 was probably not new enough for this trend (it started around 2010–2014).
The first choice for oil today is to use standard or synthetic. The next choice is which viscosity to use. Some of today’s lower-weight synthetic oils offer thinner options for viscosity than used to be available (“O-” and “5-” weight oils).
As you begin to assemble the engine (when you install the camshaft into the block and when you install the tappets onto the cam and into the tappet bores), you usually use an engine break-in oil or cam break-in oil. Chrysler/Mopar used Lubrizol oil for this purpose. Crane and Comp Cams have their own cam break-in lubes. In some cases, the cam manufacturer recommends a cam paste. Any cam break-in oil requires that the oil be changed after a short break-in cycle.
The regular oil filter attaches to the outside of the cylinder block on the passenger’s side at the rear. It threads directly into the side of the block. It is very important to have a good oil filter on any street engine. Replace it frequently.
The tricky part that relates to oil filters is the right-angle oil filter adapter, which is available from either Mopar Performance or Mancini Racing. The adapter bolts into the same location as the filter itself (a long bolt is included in the adapter kit). Then the filter threads into the adapter at 90 degrees to its original position and also rearward of its original position. The adapter kit is designed to move the oil filter for added exhaust header clearance. When installing the adapter, rotate it so that the oil filter is pointing rearward at the axle.
The windage tray is a curved piece of sheet metal that attaches to the number-2 and -4 main cap bolts. These main cap bolts have special heads that accept a small screw, which actually attaches the windage tray. The windage tray fits inside of the oil pan, so for any modification or revision you must keep the oil pan in mind. Most aftermarket trays are designed for specific stock or aftermarket oil pans; the pan and the tray are a team, whether Milodon or Moroso.
The 340 and 360 high- performance engines are the only production engines that used a production windage tray. It clears the stock 3.31-inch stroke and the 3.58-inch stroke. It may have to be modified for long-stroke 4.00-inch crank engines. In 1974 and newer engines, the tray attaching holes are slotted to fit the 340 and 360 main cap bolt widths.
The windage tray is designed to control the oil in the pan during acceleration and braking and control windage losses from the spinning crankshaft. For performance gains, I recommend using an aftermarket pan and baffle/scraper/tray. Milodon and Moroso offer many versions.
Several versions of the production oil pan are available. The 273, 318, and 340 all use the same basic oil pan. The 360 pan is unique because the end radius is smaller on the 360 pan. They are not interchangeable. Magnum pans are similar (5.2L is unique from 5.9L), but the sump locations based on the vehicle tend to be unique.
If you are building a high- performance street engine, you should increase the pan’s capacity because more oil absorbs more heat and enhances performance. Most A-engine and Magnum engine oil pans hold 5 quarts, including the filter. You want to increase this to 6 quarts or more. Moroso offers a pan with an extra quart of capacity plus baffles in the sump for better oil control. Milodon offers a deeper pan, for more capacity, and a sump that is wider than the engine block and increases the pan’s capacity without affecting ground clearance.
Milodon offers seven different levels of oil pans, which differ in volume and depth. The drag race pan and the off-road pan are too deep (more than 10 inches) for street/strip conditions. The stock replacement is just that, but it is nice to know that it is available if yours is damaged.
Also available from Milodon are the 8-quart Street/Strip pan, the 6- and 7-quart Pro Street pan, and the 6-quart Road Race pan. The Street/ Strip pan is 83⁄4 inches deep; the other three are about 7- to 73⁄4-inches deep. For most applications, the Street/ Strip pan is my first choice. If the car has a very low front ride height, one of the 6-quart 7-inch-deep pans is a better choice.
Moroso also offers a too-deep drag pan but also has an 8-quart pan that is 81⁄4 inches deep, which is a good street/strip pan. A road race pan should work well if it fits your engine compartment requirements. Champ Pans and Canton Pans also offer pans that can be used on a street/ strip engine.
High-horsepower and high-RPM engines should have one of these street/strip or better oil pans. The difficult part is where to draw the line. When a mechanical cam is added and/or the estimated power is more than 600 hp, you should upgrade to one of these pans.
The oil pan’s sump is the actual bottom of the pan (wet-sump style) and where the oil is collected after it has lubricated the engine’s moving parts and is gathered for its next trip through the pump. The typical production sump is about as long as it is wide (almost square) and the width is out to the edge of the block minus the two rows of attaching bolts. Sumps are a feature of wet-sump oiling systems.
In A-engine production pans, the sump could be located at the front of the pan (large van), in the middle of the pan (passenger car), or at the rear (trucks). Although Magnum engines in trucks and passenger cars use pans with different sumps, it isn’t as neat as an A-engine.
To increase the oil pan’s capacity, you can lower the sump. To do that, you need to cut off the sump and weld a 2-inch piece onto the pan. This increases the sump’s capacity by a quart or two, but it also reduces the engine’s effective ground clearance, and you don’t want to damage or rupture the oil pan driving over a speed bump or driveway incline. The model or vehicle and the orientation of the engine in the engine compartment generally dictate the location of the pump.
Typically, other items on the bottom of the engine compartment hit the ground before the production oil pan or they hit at the same time. If the sump is lowered, it is the first to hit. You can weld a shield onto the bottom of the K-frame to help protect the sump or just be careful when driving on uneven pavement. Dropped sumps are popular in drag racing where the tracks are basically flat.
Another performance tip (after increasing capacity) is to add baffles. The acceleration baffle is added across the rear of the sump as high as possible; it must stay below the crank. The rear baffle can be somewhat longer but the oil pick-up has to fit into the opening left between the baffles so you have to be careful. The rear baffle is angled downward at 20 degrees.
The braking baffle is added across the front of the sump at the same height as the front of the pan. The front baffle only needs to be about 2 inches long. The front baffle is angled downward at about 10 degrees.
If the pan has a rear sump, the rear baffle should be as close to the crank as possible. If the sump is in the middle, the baffle is at the top of the sump, even with the rear section of the pan.
All of the above-mentioned pans and dropped sump pans are steel pans. In many cases, they are just the attaching flange with the sides and bottom welded on, but they are still steel. The fully fabricated oil pan has been around for many years. The Mopar small-block makes it much more difficult to fabricate the pan because of the front and rear large radiuses. Once you step into the fabricated pan arena, the manufacturer (Charlie’s Oil Pans) can do almost anything, but typically these pans are used in racing. A wide-sump, close to stock height, aluminum pan with baffles is interesting for the street.
Custom pans, such as those offered by Charlie’s, can offer features that you desire but may not be readily available for your engine as “shelf” items. For example, perhaps the desired pan is only available for the 318/340 block and you have a 360 block.
Another custom pan feature is having enough clearance for steering and suspension components. A custom pan builder can address any of these issues. These custom pan builders also build big pans for drag race engines that focus on making more horsepower, but these pans are generally too deep for a street/strip vehicle.
Oil Pan Gaskets
The A-engine uses a four-piece oil pan gasket, two side gaskets and a front and a rear crossover gasket. Magnum engines use a one-piece gasket. Remember that the 318/340 and 5.2L gaskets are different from the 360 and 5.9L gaskets.
Oil Pump Drive
Another concern relates directly to the camshaft you use. If you plan on using a hydraulic roller cam or a mechanical roller cam in your engine, you should have an intermediate shaft, which uses a bronze gear or an aluminum-bronze gear. It is gold in color so it is very easy to determine if you have one. It should be pinned to the shaft. The problem is that these roller cams are made from steel and the production gear wears out very quickly when run against a steel gear. The bronze material solves this metallurgy problem.
Magnum engines, which already have a hydraulic roller cam made from steel, are tricky. Chrysler engineers solved the steel problem by alloying and heat-treating the gear. My problem is that the finished production part looks just like the A-engine production part, which should not be used with roller cams. The Magnum part should work with all rollers, but you might talk to the cam experts (Comp Cams or Crane) to see if they have encountered any issues. If in doubt, use the Magnum shaft for the hydraulic cams and the bronze gear with the bigger cams.
If the engine is being built for the street and for durability (high mileage), you might consider the Milodon bronze gear, which claims premium material for better wear resistance.
The dry-sump system allows a very low ride height for street or street/strip cars because it allows you to have very low front ends without having to worry about ground clearance for the bottom of the sump of the pan. In some custom cars, there is no room in the engine compartment for a wet-sump oil pan. A dry-sump system can help solve some of these issues. The dry sump provides a steady supply of oil under extreme operating temperatures in racing applications, but that’s not an issue for the typical street/strip engine.
Everything discussed previously relates to the basic wet-sump oiling system. A dry-sump oiling system replaces most of the bottom-end hardware: pan, pump, and filter (maybe). Many dry-sump oiling system designs started with the early 354/392 Hemi and other big-blocks in Top Fuel dragsters and racing boats. In the mid-1970s, the rules changed for NHRA Pro Stock, and big-blocks (426 Hemi) were allowed in small cars (Colt and Arrow). There was no room for a wet-sump pan in these small vehicles, so the dry sump jumped to the front of the class.
Much of the technology that is used today has its roots in this era. In this case the only parts that changed for the small-block use were the shallow pan and the front drive pulley. The typical dry-sump system has a very shallow oil pan and multiple oil pick-ups. The standard oil pump on the number-5 main is replaced with a separate four-, five-, or six-stage pump, which has one pressure stage and the rest are suction stages.
All suction stages pump oil to a remote oil storage tank, which holds the oil (8 to 12 quarts or more depending on the type of racing). The pressure stage draws oil from the bottom of the remote dry-sump tank and lubricates the engine similar to the wet-sump pump. The multi-stage oil pump is driven off the nose of the crank by a small Gilmer belt. The dry-sump pump (all stages) may be a Gerotor pump or a gear pump (the gear pumps are more popular). Typically the dry-sump pump is mounted on the lower driver’s side of the engine block, but it may be switched to the opposite side.
My recommendation on dry- sump systems is to select one supplier for all dry-sump hardware and follow all recommendations for your application. Years ago, customers didn’t use dry-sump systems because of expense. The biggest advantage of a dry-sump system is ground clearance, so that is very important to street applications.
Today, more and more “custom” street car owners want the look or style that comes with a dropped front end, and the dry-sump works in this environment. Do not mix and match your dry-sump parts. Moroso, Milodon, Dailey Engineering, and Barnes Dry Sump Systems are just a few manufacturers.
Written by Larry Shepard and Posted with Permission of CarTechBooks
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