Cast iron heads sometimes are required by class racing rules and cast iron is perhaps a bit more durable versus Chevy 350 aluminum heads. Chevy 350 aluminum heads are lighter in weight of course, and look awesome on your fresh small block.

Iron versus aluminum is a popular subject to talk about for 350 Chevy head choice. If your rules require a stock type valve size like 1.94/1.5 and the bigger 76 cc type combustion chambers, we have those on hand too, like part #91624360 from Dart, which is IMCA legal and is much better than factory open chamber retreads. The good news is that almost all of our Chevy 350 heads are equipped with the large 2.02/1.6 valve size, and they are designed to maximize flow with the bigger valves. Since the stock heads arenвЂ™t designed to let a big valve breathe as it should, the modification often yielded less flow than the stock smaller valve. The hot thing to do back in the day was to stuff the biggest valve you could find in your factory heads. In the old days, guys always talked about 2.02 valves. Chevy 350 heads can be head in as large as 230 cc intake runner size! For extremely large cubic inch engines and big, big horsepower, itвЂ™s common to reach for 215 cc and bigger intake runners. If you are shooting for higher horsepower numbers (more than 450 hp, or extremely high rpm ranges for racing applications, then a 200 cc intake runner range is where you want to be. ItвЂ™s called the E-Tec and itвЂ™s based off of the factory vortec design, only itвЂ™s better and in aluminum to boot. You can purchase this type of head from Speedway Motors, Edelbrock part #32560975. They featured 170 cc high flow, high velocity runners and can easily make north of 400 horsepower while maintaining staggering low speed torque. A perfect example of this is the factory GM vortec type head. If the runner is too large, the engine can get lazy at low RPM. The intermediate runners flow enough air for that 400 hp power requirement, and they keep the mixture velocity high enough to help insure good low speed torque production. This is the runner range you want to stick to with your 350 small block heads for that 400 hp range. Many units check in around 180 cc port volume, some might be around 170, others closer to 190 just depending upon the manufacturer.

In this range, an intake runner less than 200 cc is best. LetвЂ™s just suppose we are building a 400 hp street 350 small block. When it comes to intake runner volume, bigger is not always better. WeвЂ™re gonna talk about intake runner size, valve size and materials like aluminum vs. When it comes to choosing which Chevy 350 heads to buy, the choices are many, but letвЂ™s narrow it down for you. The trick is to match the parts correctly. The bottleneck in airflow is gone when the heads do not restrict airflow. On the other hand, if you have a quality flowing set of Chevy 350 heads with a not so big cam, carb, and dual exhaust, the engine will still perform. Big cam, big carb, headers and poor flowing heads equals a doggy running mill. If you donвЂ™t have a modern set of good flowing Chevy 350 heads, your engine is gonna be a stone. ItвЂ™s easy to avoid the вЂњno horsepowerвЂќ blues when you choose the correct small block Chevy heads for your build. If youвЂ™ve got a small block with the later open chamber, small valve heads, the situation is even more dire. Yes, they were good for their time, but using those today makes no sense when you want to go north of 350 horsepower. The old iron double hump heads with 2.02/1.6 valve size. All these engines had different displacements, but they all had one thing in common: the same set of heads. They all made about the same peak gross horsepower. The 1970 350 LT-1, the famous 302 Z-28 and also the 327-365 hp Corvette engine. No matter what you do for cam, intake and carburetor, you are going to be limited in power potential unless you address the real bottleneck in the small block Chevy engine, which is its cylinder heads.Дyno tests have been done extensively on all the factory early high performance small block Chevys. A set of original, bone stock Chevy 350 heads flow less than 200 cfm of airflow on the intake side.

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