CC and Surface Mill - Out of the box combustion chamber sizes vary from 48-50cc's, with the average size being 50cc's. For best results, cc the cylinder head so that all chambers are the same size or within one cc, which translates to roughly one tenth of a point in C/R on a 200ci motor, less on a 250ci. Then surface mill the cylinder head so that the desired chamber size (compression ratio) is achieved. This will vary depending on deck height, head gasket thickness, cylinder and gasket bore size, and combustion chamber size. We recommend a C/R of 9:1 to 9.5:1 for street applications. Race builds may utilize higher compression ratios, but caution must be observed to prevent detonation and/or pre-ignition. Extreme compression ratios may require the use of water injection or other means of preventing pre-ignition and/or detonation. Warning: High C/R's may lead to pre-ignition and/or detonation, which may results in severe engine damage or failure (see warranty).

Spring Pockets - DO NOT cut the valve spring pockets any deeper, so as to increase the valve spring installed height, as this may result in small cracks and/or holes in the intake runners. While it may or may not be visible to the naked eye, it can result in excessive oil being sucked into the combustion chambers, thus fouling the spark plugs, mufflers, and the entire exhaust system in a bath of oil. The cylinder head can be repaired by a quality shop (by welding and re-machining) however it is quite expensive. To compare the intake ports and combustion chambers of a cast iron and our aluminum head, see the cross sections.

Spring Pressure & Installed Height - The valve spring installed height on our aluminum cylinder head is 1.6, as compared to 1.68 on the cast iron heads. As such, the valve spring pressures are higher, while spring clearances (coil bind) are reduced. For more information please see our tech article on valve springs, which includes specs for the springs we sell.

Reduce Your Ignition Timing - According to our design engineers, the ignition timing may need to be reduced to prevent pre-igniton and/or detonation. Failure to do so could result in severe engine damage. It is best to start on the low side, then gradually increase the ignition advance until properly set. For more info, see our tech article on ignition timing.

Check and Verify - It is extremely important to double check the pushrod lengths, pushrod side clearance, rocker arm geometry and clearance, valve spring coil bind, ignition timing, cylinder head torque values, carb linkage and/or throttle cables, vacuum connections, fuel lines, and oil level, prior to engine start up. This is critical on new engines which need to go through the initial breakin period (2000 rpm for a minimum of 20 minutes). Also remember to prime the oil pump, and to check the oil pressure during the start up procedure. .

Studs vrs Bolts: We recommend using studs instead of bolts, whenever possible, for several good reasons. Studs offer a more uniform and accurate torque load, as well as increased clamping force, which aids in the prevent-ion of gasket failures. Studs make it easier to assemble an engine, and insure the proper alignment of gaskets. Plus they greatly reduce the likely hood of stripping aluminum threads, caused by over torquing. See our tech article on ARP Studs for more information and installation tips.

Always use Anti-Seize - All bolts, studs, screws, pipe plugs, spark plugs, sending units, or anything that threads into aluminum must be coated with an anti-seize lubricant.

Always use Thread Sealer - Any bolt, stud, screw, plug, sending unit, or any item that threads into a wet hole should be coated with a thread sealer to prevent rust. One such bolt (stud), is the head bolt (stud) closest to the thermostat. It is often missed as it is the only head bolt (stud) that threads into a wet hole.

Coldest Spark Plug 1st - Always start with the coldest spark plug first, then move up the heat range as required. A plug which is to cold will simply foul out over time, which can be replaced with a hotter plug as needed. A Spark Plug which is to hot may cause pre-ignition and/or detonation, resulting in severe internal engine damage.

Check all Gaskets - Cylinder head, intake, and exhaust gaskets should be checked and trimmed accordingly, so as not to cause any interference or obstructions. Check intake and exhaust gaskets for any interference in the ports and runners, as this may create turbulence, resulting in reduced air flow and performance. Check head gaskets for correct size and alignment of water ports and oil passageways, as any blockage may result in severe engine damage. Always use the appropriate gasket sealer.

Note: While our universal intake manifolds accept 2V and 4V carbs, with the proper adaptor, they are not a simple bolt on installation. While the 2V is fairly straight forward, the installation of a 4V carb may present several obstacles to overcome, including but not limited to manifold and carb clearances, carburetor linkage, and automatic transmission kick-down linkage. See Clearance Issues for more information.

Maximum Air Cleaner Size - For most applications, a 10" round air cleaner is the maximum size allowable due to shock tower clearances. A small oval may be used in some cases.

Note: If you have a tip or suggestion to share, which will help future customers with their installs, please send us a detailed message via E-mail. Thank you very much.