Deck Surface Milling

Flat milling: .006" per cc
Angle milling: .0075" per cc

Excessive milling can cause intake manifold port misalignment, which may require corrective machining to the intake manifold or other measures in order to achieve proper intake gasket sealing.

Note that a combination of different thickness head gaskets and/or intake manifold gaskets will also effect port alignment.

Refer to cylinder head bolt manufacturer's specifications for torque setting.

Torque head bolts/studs to specified setting in 10 lb/ft increments, starting at 35-40 lb/ft. GM factory torque sequence must be followed for proper head gasket sealing. Bolts/studs that enter coolant passages should be coated with a thread sealant such as Permatex.

Bolts/studs that are being threaded into aluminum should be coated with anti-seize lubricant to prevent thread damage. All other bolts and studs should be lightly lubricated with 30 wt engine oil.

Before installing your new RHS™ cylinder heads, be sure to run a tap or thread chaser through all of the head bolt holes in your engine block in order to ensure clean threads and accurate fastener torque readings.

Intake manifold bolts should be torqued to 35 lb/ft in 5 lb/ft increments, starting at about 20 lb/ft.

GM factory torque sequence must be followed, and all bolts that enter water jacketing should be coated with a good thread sealant such as Permatex, in order to prevent coolant leaks.

If using valve springs other than those listed by application for your specific RHS™ cylinder head model, you must verify that the valve spring is appropriate for use with your camshaft and engine application.

Installed height, coil bind clearance, seat/open pressure, and spring rate must all be verified to be correct before the engine is run, or severe engine damage may result.

Call Racing Head Help™ toll free at 1-877-776-4323 if you are not sure that your valve springs are correct for your application.

Valve spring pockets can be machined to 1.625" maximum diameter, but cannot be machined any deeper.

If additional valve spring installed height is required, valves with longer stems or valve locks/keepers that provide increased installed height may be used.

Measuring with pushrod length checker such as COMP Cams® #7705, is required in order to verify pushrod geometry.

Incorrect pushrod length can cause poor performance, accelerated valve train wear, and/or engine damage. Note that there is no “standard” or “recommended” pushrod length unless your engine is bone stock, from air cleaner to oil pan. Pushrod geometry must be verified!

All cylinder heads that are to be run with guide plates must also be run with hardened steel pushrods that are intended for use with guide plates. Failure to use hardened pushrods will result in premature wear of the pushrod where it contacts the guide plate, which in turn may result in severe engine damage.

Contact COMP Cams® CAM HELP® at 1-800-999-0853 for a guide plate-compatible pushrod recommendation once the required pushrod length is known.

Piston to valve clearance must be verified – the minimum clearance is .080" on the intake side and .100" on the exhaust side.

The easiest method of verifying piston-to–valve clearance is to check using modeling clay on top of one of the pistons. See the COMP Cams® Master Reference Guide or www.compcams.com for detailed instructions on using this method.

Valve Guide Clearance

Valve guide clearance must be checked due to the variance in valve stem diameters between manufacturers. Recommended clearance is .0015"-.0016" for the intake valves, and .002"-.0025" for the exhaust valves.

Valve head margins and dishes will have an impact on advertised combustion chamber volume.

For accurate compression ratio calculation, the combustion chambers must be cc’ed with the valves installed in the cylinder head in order to verify the exact combustion chamber volume.

Pre-install cleaning

Spark Plugs

Use the spark plug application chart below to determine which spark plug best fits your application. Note that forced induction or nitrous engines should use spark plugs 1-2 heat ranges colder than those listed in the chart.

Be sure to use anti-seize lubricant on the threads of spark plugs installed into aluminum cylinder heads.