Usage:
- SUPPLEMENT: 02/24/86
SERVICE MAGAZINE, JANUARY 27, 1986, PAGE 4, "Uprated 3500 Series Engines Now Available". In the charts for the 3508, 3512 and 3516 Engine Arrangements, several part numbers were omitted. Also, in the chart for 3508 Engine Arrangements, the 95W644 serial number should be 95Y644. The correct charts are listed below.
--------------- END SUPPLEMENT ---------------
Reference: "Uprated 3500 Series Engines Use Stronger Pistons, New Connecting Rods And New Piston Pins" in this issue.
Uprated 3500 Series Engines are now available. Design and manufacturing changes have resulted in improved structural and component capabilities. These improvements allow a rating increase of up to 25% above the previous levels, while the brake specific fuel consumption will decrease by up to 3%.
Improvements to some of the basic engine components such as the cylinder block, crankshaft, camshaft, valve train, pistons, rods, wrist pins, cylinder heads, turbochargers, inlet manifolding, fuel injectors and fuel lines have allowed the uprating of the 3500 Series Engines.
This article will address some of the improvements which have allowed the higher ratings. Part numbers of some components have changed and former parts should not be used to service the uprated engine.
Illustration 1. Location of the drilled oil galleries.
Cylinder blocks have increased wall thickness in key locations to make the block stronger. The oil galleries are now drilled rather than cast. These improvements have increased the fatigue limits of the block. This allows the block to be used at higher ratings without decreasing the reliability of the block.
Crankshafts used in 3512 and 3516 Engines have improved heat treating. The manufacturing process for the crankshaft oil supply holes has been changed to reduce stress concentrations. These changes will result in stronger crankshafts.
Illustration 2. Former and new camshaft drive gear retainers.
Camshaft lift, duration and profile have been refined to provide increased efficiency. The camshaft drive train has been improved to carry more load, as shown in Illustration 2. One larger bolt is now used, rather than two smaller bolts to fasten the camshaft drive gear on the end of the camshaft. This provides a stronger gear-to-camshaft joint and is simpler to assemble.
Illustration 3. Cross sections of the forged piston and the cast piston.
Illustration 4. Forged piston and cast piston.
Illustration 5. Bottom view of the forged piston and the cast piston.
Two types of pistons are now used. One type piston is of all cast construction and is used in lower and intermediate rated engines. The other type piston has two parts; a forged skirt, pin boss and central crown with a cast outer crown. These two piston parts are electron beam welded together. This welded type piston is used in the new uprated engines.
Illustration 6. Connecting rod used with the welded piston and the connecting rod used with the cast piston.
Due to the increased piston crown thickness, a new connecting rod with a different small end balancing boss is used. This will provide sufficient clearance between the top of the rod and the undersize of the piston crown.
Illustration 7. New and former intake and exhaust valves.
Piston pins have been improved but the difference is hardly discernible to the naked eye. The improved piston pin is required for proper break-in and satisfactory performance under the increased load. The former pin is not to be used with the welded pistons.
Illustration 8. New and former rocker arm shafts.
Illustration 9. New and former injector rocker arms.
Illustration 10. New and former rocker bases.
Illustration 11. New and former valve covers.
Many new, improved valve train components are used with the uprated 3500 Series Engines. The intake and exhaust valves now have thicker head and face areas. The rocker arm shafts have improved hardening techniques and thicker mounting spades. Push rods have improved heat treat techniques. The injector rocker arm is stronger and has a longer adjusting screw. The aluminum rocker bases have been changed to provide additional strength. The valve cover height has been increased to provide clearance for the stronger injector rocker arm.
Illustration 12. Cross section of new and former cylinder heads.
Illustration 13. New and former cylinder heads.
New cylinder heads have increased strength through the use of internal gussets which reduce cyclical deck distortion. This increases the strength of the lower deck surface of the head. These changes improve gasket sealing which is required for the increased cylinder pressures. The exhaust port shape has been modified as part of the structural design improvements.
New higher efficiency turbochargers have been selected to optimize the performance of the uprated engines.
Inlet manifolding and air shutoff equipment have also been changed to accommodate the uprated engines.
Fuel injection system improvements include new fuel line adapters to ensure a positive pressure in the fuel injection supply cavity at higher injection rates.
Many of the former ratings will continue to be offered for customers not requiring the uprated engines. These will be called "intermediate rated engines." These arrangements will contain some different components than the uprated engines. The "intermediate rated engines" do not require the extra strength in all areas of the engine because they are not rated as high. These intermediate rated engines do not require the use of the new piston or improved turbocharger; and, additionally, they may be equipped with a different damper. This allows a customer, who does not need the full increase in power, to have a more price effective engine. However, if the customer wishes to increase the power of an intermediate rated engine (above effective serial numbers listed in the chart) at a later date; the pistons, turbochargers and possibly the dampers will need to be replaced.
Customers who have earlier engines, below the effective serial numbers shown in the charts, may wish to uprate their engines. This is NOT recommended. The parts required to uprate the engines would include the block, crankshaft, camshaft, valve train, pistons, rods, wrist pins, cylinder heads, turbocharger, inlet manifolding, fuel injectors and fuel lines. Replacing all these components would not be cost effective.
Illustration 14. Location of the engine serial number and arrangement number on the Information Plate.
To determine if you have an "intermediate rated engine" or an "uprated engine", look at the information plate. Compare the serial number and arrangement number with information in the charts that follow.
The new engine arrangement numbers are in effect as shown in the charts.
Many of the improved parts used on the new uprated engines can be used to service the earlier engines. This can reduce the need for extra parts when a mixed fleet of new and earlier engines is involved.
The chart that follows outlines the adaptability of some new parts to earlier engines. The new improved parts used on the new uprated engines are listed in the left column of the chart. Their adaptability to earlier engines is indicated in the right column (Yes/No) along with any comments. This chart is for reference only, and will not be updated.