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What spark plug should I use with my AFR cylinder heads?

The following list of spark plugs are suggestions for getting your engine up and running. In order to determine the correct heat range for your application, we recommend pulling your plugs and inspecting them a few times under typical operating conditions; commonly known as reading the plug. Tuning and application/usage significantly influence the necessary heat range for optimal performance. Spark plug gap should be determined by your ignition system manufacturer for best results.

- 3/4" reach, 14mm, gasket seat

- Autolite #3924  or equivalent for normally aspirated, pump gas engines with a compression ratio between 9:1 and 11:1

- Autolite #3922, or equivalent for engines with high compression, between 13.5:1 and 15:1, or boosted applications over 15psi running Race Gas

What should I torque my bolts to?

Aluminum cylinder heads with factory bolts should be torqued to 70-75 ft./lbs using Permatex thread sealant with Teflon. Be sure to follow the proper GM torque sequence, starting at 40 ft./lbs and increasing by 10ft./lbs until reaching the recommended setting. All engines with high compression or using power-adders should be re-torqued after the first run-in, after it has completely cooled-down. In addition, (4) one inch longer space fasteners must be used, per side, along the exhaust port(bottom) of the cylinder head.

If you are using ARP hardware, follow their recommended torque specifications. Rocker studs should be torqued to 50-55 ft./lbs using Permatex thread sealant with Teflon. Spark plugs and all intake and exhaust bolts should be tightened with a standard wrench or socket versus a torque wrench as these smaller threads can easily strip. Be sure to apply anti-seize to all threads prior to tightening.

Are there any other special parts that I need with my AFR cylinder heads?

Your AFR cylinder heads will accept most factory GM components. However, if you require a stud girdle, you must use our #6202 which has been designed specifically for our V2 castings. Conventional stud girdles will not fit properly.