14 And then you put everything else back in place. Sounds easy, and it was. Distributor (with the new gear), intake, carb, valve covers, timing cover, oil pan, front drive, radiator, water, coolant, fuel lines, and belts … and then it was dyno time.
15 With no additional changes (just the new camshaft) we recorded a new peak horsepower of 295.70 with peak torque ringing in at 343.74 lb-ft. That's a nice gain of 11.07-rwhp and 8.8 lb-ft of torque. Of course, the real gains were
16 There is only so much you can do with a pair of super-low-buck cylinder heads, and all of the camshaft and cubic-inches in the world won't make a difference if you can't get air in and out efficiently. Air Flow Research said it could solve that problem, and Greg barely let our 383 cool before he started pulling the long-tube headers out of the engine bay.
17 Pulling the cylinder heads requires almost the same labor as pulling the camshaft, although the radiator and front timing cover can stay in place. Fast forwarding a little, here you can see Greg removing the head bolts from the block, after he already pulled the valve covers, intake manifold, rockers, pushrods, and other miscellaneous items out of the way.
18 And just like that, the old heads were coming off. Officially listed as 190cc cylinder heads, these budget pieces reportedly flowed 260cfm on the intake side and came equipped with 2.050-inch intake and 1.600-inch exhaust valves (same valve size as our AFR's) and 64cc chambers. They served us well, but we knew a serious cylinder head with heavy development work could outshine them.
19 If we were going to go through all of this trouble, we wanted to make sure we did it right. Enter the 23-degree 195cc SBC Eliminator Street cylinder heads from Air Flow Research. With 65cc combustion chambers, 2.050/1.600-inch valves, and 100-percent CNC-ported combustion chambers, intake, and exhaust ports, along with a competition five-angle valve job, these beauties flow 280cfm at .550 lift.
20 Lightweight 8mm 2.050-inch intake valves, paired with 1.600-inch exhaust valves fill the CNC-ported combustion chambers, which also feature a 5-angle competition valve job. With a thick .750-inch deck and 65cc chambers, these heads would do great with a little boost or a shot of nitrous, but we're running good old atmospheric air through our 383.
21a Both the intake and exhaust ports have been heavily worked by the engineers and machinists at AFR, and the results speak for themselves. 280cfm of flow on the intake side at .550-inches of lift and 218-cfm on the exhaust port (with a 1.75-inch pipe) is great for a 195cc street head.
21b Both the intake and exhaust ports have been heavily worked by the engineers and machinists at AFR, and the results speak for themselves. 280cfm of flow on the intake side at .550-inches of lift and 218-cfm on the exhaust port (with a 1.75-inch pipe) is great for a 195cc street head.
22 New cylinder heads require new cylinder head gaskets, and we chose to run a complete 4.165-inch top end gasket kit from Cometic (P/N PRO1003T; $285.55). These Multi Layer Steel (MLS) gaskets will handle big cylinder pressure for years to come and ship complete with practically any bore size and compression height that you may require.
23 The new AFR 195cc Street heads dropped right in place and bolted up without any issues. Here you can see Greg torqueing the head bolts to 75 ft-lbs using Permatex thread sealant.
24 AFR also included its adjustable guide plates, which makes centering the pushrod and rocker arm a breeze. Greg prefers to loosen the guide plate bolt, center up the rocker arm, then tighten everything down. Once set, it's time to set rocker arms, and get ready to fire the engine up.
25 But first we had to install our new AFR aluminum CNC engraved valve covers (P/N 6704; $169.00). These beauties easily cleared our Crane rocker arms and included rubber grommets for installing breathers. Always a nice way to spruce up an engine bay, and they'll keep our valvetrain and engine happy for years to come.
26 Drumroll please … and wow! The new AFR heads took our 383 from a 295-rwhp driver to a 343.10-rwhp rocket. That's a gain of 47.9-rwhp from an already decent set of aftermarket heads. Not to mention the 373.64 lb-ft of torque, which was way up from the 344.09 baseline with the new camshaft. That's a 29.9 ft-lb gain at peak torque, which is awesome. Overall, with the new AFR cylinder heads and the Crane Cam package, our 383 was up 57.69-rwhp and 38.56 lb-ft of torque. Now that's what we're talking about! Look at the improvements under the curve and the difference past peak power. Huge gains.