GM’s New Family of VVT Gen IV Cam Cores
The new style became the exclusive unit in most 2009 and newer engines. • Original (old style) GM Part #12585994: 2007?2008 (uses cam core 156?family) •Current (new style) GM Part #12606358: 2007-2009 and newer engines (use cam core 189?family). The difference in the camshaft core is the pin to centerline position. The difference in the
Using Valve Lash to Help Tune the Engine
If you decrease the amount of (hot) valve lash, for example, the valve will open slightly sooner, lift higher and close later. This makes the camshaft look bigger to the engine, because of a slight increase of actual running duration and lift. If you increase the amount of (hot) lash the opposite occurs. The valve
Extending Valve Life
Most manufacturers of valvesoperate tech phone lines, and all have received that caller who opens the conversation by saying, "Your valve ruined my engine; when are you going to pay to fix it?"As much as the rebuilder or vehicle owner might like to lay blame it on the manufacturer for providing a bad product, it
7 Shop Survival Tips
Ford 5.0L/302 "Cobra" Cams Problem: Ford made a limited number of the Mustang Cobras with a "super-high-output" 5.0L in ’93, ’94 and ’95. They all had a unique roller cam (p/n F3ZZ-6250-A) that can be identified by the "GT" stamped on the barrel, right behind the distributor gear (see Figure 1, at right). This cam
Thermal Considerations for High Performance Engines
Temperature affects the size of all the materials. However, the effect is certainly not the same for all materials. Almost all materials expand as they are warmed and contract as they are cooled. There is one noteable exception – when water changes to ice. Returning to the subject at hand, we find that for all
Finding the Weak Link in Nissan KA24 SOHC Engines
Many of you may have not seen this issue, but once it bites you, you will always remember the Nissan KA24 engine series in the SOHC configuration. ? When the timing chain, guides and tensioner get high miles and wear the chain can actually start rubbing against the front of the block (Figure 1). ??
This Super Duty Was a Super Headache
By Eric Seifert, Automotive Technical Editor Some 5.4L 3-valve engines found in 2004-’05 F-150 and 2005 F-Super Duty, Expedition and Navigator vehicles may experience difficulty with spark plug removal, which may cause damage to the spark plug and leave part of the spark plug in the cylinder head. Repair Procedure If the plug does come
Lower Cylinder Bore Damage Caution for CAT 3400, C15, & C18 engines
The wear shown in Figure 1 is an example of the damage that can result on a worn cylinder block. The cylinder block should be repaired prior to installing a new cylinder liner. With newer engines developing higher cylinder pressures and horsepower, and older engines possibly having been overhauled a few times already, making sure
Manganese Phosphate Coating on Compression Rings
This black coating is on the ring for two important reasons. The coatingis manganese phosphate. The reason rings are coated is twofold (1) rustprevention and (2) oil retention for protection against scuffing in early engine operation. Rust prevention is necessary for the period of time the ring is in the set box sitting on a
Cylinder Head Caution for Mercedes M112 and M113 Engines
Sealing surfaces of the crankcase and cylinder heads are provided withan 0.8 mm thick silicone layer (Loctite 5900) during standard factoryassembly. Silicone sealant should be applied during repair assemblyonly if sink holes exist in the sealing area. When cleaning sealing surfaces of the factory applied silicone sealant,during cylinder head reassembly, extreme care must be taken
Wet Sump and Dry Sump Oiling System Differences
Theuse of a wet or dry sump oiling system is often determined by the levelof competition and the racer’s budget. A wet sump system is based onthe original equipment oiling system, and can be enhanced with certaincomponents to improve oil control and increase power. A dry sump systemis designed for the top levels of racing
Revised Cylinder Head Torque Specs for Saab 2.1L B212 Engines
Affected vehicles: 1991-1993 Saab 900 with 2.1L engines (B212). The torque procedure cards included in Saab B212 cylinder head gasketkits, P/N 93 21 597 and B212 cylinder head gasket, P/N 87 87 111, areincorrect. The correct specifications are as follows: • Stage I: 44 ft.lbs. (60 Nm) • Stage II: 59 ft.lbs. (80 Nm) •