This continues almost to the bowl beneath the valve, which is good for performance and simplifies porting. These are respectable figures for what is essentially a very low-cost head. This head would be perfect for a big torque application on a 383 or 406ci small block aimed at a truck or towing application. Used on 396ci and 427ci engines. Also note the lack of a polished finish on the ports.
To avoid this, stroke it. Dusty makes a power move that, though time consuming, is worth passing on. This makes your porting efforts, combined with a valvetrain accessing the extra airflow, add up to yet more power. He takes a Scotch-Brite pad and gently polishes the rings so they feel smooth. The Chevy big-block has been installed in millions of cars and trucks over the past 50 years, including Camaros, Chevelles, Corvettes, Impalas, and a multitude of trucks. That is why all aftermarket heads are made with open chambers. Degreeing the camshaft is an important step in the build process.
While iron heads are usually less expensive than their aluminum-alloy cousins, there are also disadvantages to the cast iron route. Factory big-block Chevy heads were offered in both aluminum and cast iron, both open- and closed-chamber designs, and oval passenger car or rectangular high performance intake ports. With the carb installed and a few other little details taken care of, our 492 was ready for the dyno. The goal is to assemble a pump gas 500 + horsepower, maximum torque big block on a limited budget. Such heads can deliver impressive results, not because they are a rectangular design, but because the volume is appropriate for the application. I ported a set of them for a nonnitrous street application for a friend right after they became available. Shops might also want to consider a head that allows for future growth down the line.
Leak Detection Tech Tip: Checking For Leaks During the build process, Hardcore checks every single engine they complete for water and oil leaks. Used on 402ci and 454ci engines. The real beauty of having Scat balance the rotating assembly is that they machine off most of the excess material from the counterweights in a lathe. Torque and drivability have also taken a big leap. Extracting maximum performance has been the pursuit of engine builders ever since this engine was new in 1964. After several seasons of drag racing, this engine was rebuilt as a nearly max-performance 565 build. For a typical street or bracket racing application, that extra flow is usually not critical, so the less expensive head is the better deal.
Used on 366ci and 427ci truck. The Chevy big-block has been substantially under-valved, and the key to getting the best performance from this engine is to deal effectively with this design limitation. The customer wanted to retain the ability to chug around on the water using nothing more than 87 octane fuel. The abundance of cubic inches is staggering, and the canted-valve cylinder heads are largely responsible since they flow a seriously large amount of air. So they often recommend heads with big ports.
This refers to shifting the intake valve closer to the bore centerline in order to move the intake valve away from the cylinder bore wall. The best place to concentrate on port work is the area 1-inch below the valve seat. Many heads have what is basically a rectangular port, but may also have a relatively small-volume port. Terry wanted to know if I knew anybody who could port a set of factory iron heads really well. The size of the intake port and runner is a very important issue when it comes to head design. Used on 366ci and 427ci truck engines. Optional upgrades like titanium valves or retainers are available for hardcore racers with aggressive cams and high-rpm applications.
But before getting into porting and flow bench testing, all of the heads I cover here typically respond very well to the basic no-flow-bench-needed porting procedures I talked about in the previous book. The exhaust port generates a good 70 to 80 percent exhaust-to-intake relationship with a standard 64cc chamber size. At engine speeds below this point, the air has not achieved sufficient speed to fill the cylinder entirely. This is an easy way to see what they do during the build. Just as I finished porting these heads, which, by the way, flowed much better than I expected, Terry Walters had two sets come into his shop, each with less than 1,000 miles on street builds, and both sets had dropped intake seats.
Doing this means paying very close attention to every aspect of the build and understanding that the number-one point of failure is the selection of an incorrect camshaft. This is for additional clamping and better head-gasket retention when used with blocks that have provisions in the lifter valley. This is also an extended- tip plug where the center electrode projects into the chamber. On the dyno, the Chad Speier—modified heads proved their worth by delivering 850 hp from a 468-ci engine. My first encounter was to rebuild and port a set of well-used abused might be a better term 310 heads for an acquaintance. The flow numbers and dyno results of numerous head tests indicate that the best peak and average outputs are seen when the 0.
The point is that intake port cross-sectional area is amajor player in the torque and horsepower game. It was only down about 5 lb-ft over a purpose-built 900-cfm 4150 at 2,000 rpm, but was up over 20 hp at peak, and about 30 up at 8,000 rpm. The budget part is achieved by choosing the right parts the first time, and not duplicating your efforts. The first E-Street heads I received were bare. With close inspection, you can see that it veers off to the left of the port.