Engine Builder Shop Solutions: October 2010 - Engine Builder Magazine

Engine Builder Shop Solutions: October 2010

GM Castech Cylinder Heads

I’m sure most of you know by now about GM’s 4.8L and 5.3L Vortec Gen III and Gen IV V8 engines with Castech cylinder head castings. GM has sent a Technical Service Bulletin (TSB)  for Castech specific cylinder heads that are prone to cracking. GM’s TSB #06-06-01-019B covers 4.8L and 5.3L engines with VINs V, T, M, B, Z from 2001-2006.

Be sure to check for signs of cracking if you encounter these engines/vehicles. And when pricing these jobs be sure to allow for additional costs. The conditions may result in a slow loss of coolant with no sign of leakage, or continued coolant loss after overheating the engine from a cooling system failure. Castech heads are identified by a symbol that looks like a battery on the casting.

Bill Williams

Beaver Ridge Auto

Fairplay, CO

 

Drilling Out Broken Bolts Freehand

Have you ever had to drill out a broken bolt by hand? A good way to start it is by grinding the tip of the broken bolt with a round burr with your die grinder. You are going to make the tip of the bolt a “Bowl” shaped depression. This will make it easier to find the center and this helps keep the bit from walking.

Jeff “Beezer” Beseth

Beezer Built Inc.

Newtown Square, PA

 

Pushrods And Guide Plates

Based on the number of inquiries we get at Engine Pro, there is a great deal of misunderstanding concerning what the relationship should be between pushrods and guide plates.

First, a pushrod must be hardened when used with a guide plate. Pushrod hardness is usually in the 50 to 60 range using the Rockwell C hardness scale.

The guide plate is NOT hardened. Guide plates for both OEM and the aftermarket are produced from mild steel.  Hardness on the Rockwell C scale can go from not even registering on the scale to a reading of 10 to 12.

What is the purpose of a guide plate? The guide plate acts as insurance for the maintenance of correct lifter to rocker arm geometry. It is designed to keep the pushrod in place during extreme operating conditions. 

The pushrod should not be in constant contact with the guide plate. A simple way to check for contact is to rotate the pushrod by hand with the valve closed. If there is contact, there is a problem with the geometry of the valvetrain, usually involving the rocker arm stud, since a rocker arm stud is the fulcrum between the lifter and valve.

Bob Mitchell

Engine Pro Product Development

Wheat Ridge, CO

 

How Much Pressure On Head Bolts?

In a typical V8 engine peak combustion pressures could be around 1,100 psi, which means each cylinder exerts about 14,000 lbs. of pressure on the cylinder head at full throttle. In fact, each head bolt may have to handle more than five tons of force!

Lift-off force is the clamping load that is required to keep the head sealed under conditions that may be three times higher than the peak force exerted on the head. This could be up to 3,800 lbs. per bolt, with high performance and diesel applications being even higher!

Head bolts are designed to stretch as much as .006? to .010? or more depending on the application, so replacing them when you assemble an engine is a good idea even if it is not required.

Torque-to-yield (TTY) head bolts are used on many modern engines, especially engines with aluminum heads. A TTY bolt will stretch and then spring back to its original length only up to its yield point. This requires the bolt to be replaced after one use.

As a rule one must clean the threads in the block and use motor oil on the threads before installation. The torque specifications are based on oiled threads, not dry. Typically 10W30 multi-viscosity is used. Don’t forget to make sure your torque wrench is accurate, and use new head bolts with every rebuild.

Bill Williams

Beaver Ridge Auto

Fairplay, CO

 

Head Bolt Installation

In today’s competitive environment, there is little room for error. Costly comebacks not only take away from already modest profits, but can also harm a good shop’s reputation. Attention to the small details can often make a big difference!

Long-standing head bolt installation techniques are often assumed to be correct, while, in some instances, traditional practices can result in significant problems.

One example is head bolt installation thread lubrication practices. While many shops use white lithium grease, studies have shown that lightweight engine oil is a better lubrication choice providing a better average clamping load and a tighter range of clamping loads than lithium grease. A good lubrication choice for performance applications is ARP moly or Engine Pro moly lube paste.

Using light weight oil or moly lube as an alternative to white lithium grease, always replacing torque-to-yield bolts and consistently following original equipment manufacturers installation specifications should ensure consistently good results!

Lamar Whitman

Engine Pro Tech.Committee

 

Magnetic Base for Aluminum Heads

Need an easy and inexpensive way to mount your magnetic base to an aluminum head? Take the metal plate off of an old small block Ford oil pump, (302/351). Bolt it to the valve cover bolt holes and you have a sturdy mount for your base. Save the 1/4? bolts from the pump because they are the same as the bolts on the cam thrust plate on the 302-351W series Ford engines, and they always get lost!

Jeff “Beezer” Beseth

Beezer Built Inc.

Newtown Square, PA

 

Engine Builder Shop Solutions is sponsored by Engine Pro,
a consortium of 14 engine parts specialist WDs operating 33 branch
locations serving engine builders/rebuilders across the U.S.
Shop
Solutions published in each issue of Engine Builder Magazine are
awarded a $100 Visa Gift Card. Winners will be chosen by
the staff of Engine Builder Magazine and the Engine Pro Technical
Committee.

To submit a Shop Solution simply mail your entry
to Engine Builder Magazine, Shop Solutions, 3550 Embassy Parkway,
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Solutions may also be
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