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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 #3923 or equivalent for compression ratios between 11:1 and 13.5:1 or mildly boosted(8-12psi) applications running Race Gas

- Autolite #3922 or equivalent for engines with high compression, between 13.5:1 and 15:1, or high boost(15+psi) applications running Race Gas

What should I torque my bolts to?

Make sure to use Permatex thread sealant with Teflon.

289ci / 302W (7/16" factory head bolts) - 70ft./lbs. for the short bolts. 80ft./lbs for the long bolts.

351W (1/2" factory head bolts) - 100ft./lbs. for the short bolts. 110ft./lbs. for the long bolts.

For your convenience, we stock complete and partial ARP head-bolt kits, studs and washers. Our 1402 and 1472 cylinder heads are machined for 7/16" head bolt diameters; all others are machined for 1/2" head bolts. When using heads with 1/2" holes on blocks with 7/16" threads, we recommend using ARP's 254-3708 or 254-4401 kit with their 200-8598 bushings.

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.

Will the RENEGADE cylinder heads equipped with 2.02" or larger valves fit my stock pistons?

Typically our cylinder heads that are equipped with 2.02" or larger valves do not clear factory pistons or aftermarket pistons that mimic a factory style valve pocket. Regardless if it is a fresh engine build or a cylinder head swap, piston-to-valve clearance must always be checked for depth and radial interference prior to startup. The use of modelling clay is highly recommended for this procedure. Minimum clearances on depth are .080" on the intake and .100" on the exhaust, radial clearance should be no less than .020" around the perimeter of the valve. If your measurements are below the minimum it will be necessary to notch the pistons or replace them all together. Failure to do so may result in catastrophic engine damage, voiding your warranty.

Can I use my stock rocker arms with the RENEGADE cylinder heads?

The stock rocker arms can be used with our #1472 and #1492 cylinder heads, which come with the pedestal style bosses. The other cylinder heads in our RENEGADE line require stud mounted rocker arms.

What gaskets do you recommend using with my RENEGADE cylinder heads?


165cc Street - AFR #6828 or Felpro #1250

185cc Street, 195cc Comp and 205cc Comp - AFR #6832 or Felpro #1262

220cc Comp - AFR #6812 or Felpro #1262R


165cc Street and 185cc Street - AFR #6837 or Felpro #1415

195cc Comp, 205cc Comp and 220cc Comp - AFR #6839 or Felpro #1487

Head Gasket:

Factory block (289W, 302W and 351W) - AFR #6808 or Felpro 1011-1

Aftermarket Block - Consult with block manufacturer for recommendations