Cylinder Head Development: From Iron to Aluminum and 18-Degree Designs (Generation 2)

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History of Chevy's NASCAR Engines: Small Block Evolution Details Up Close With a Legend (SB2 & R07)

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The evolution of cylinder heads saw a move from fragile cast iron designs, which frequently cracked during 500-mile races, to more reliable aluminum heads. Builders even used ceramic sealer before and during races to extend the life of the iron heads. The aluminum Pontiac small-block Chevy head, made by Brodix, proved to be much more reliable and easier to work with, offering better performance. Chevrolet's later introduction of an 18-degree head, cast directly with the desired valve angle, eliminated the time-consuming and expensive process of welding and milling standard 23-degree heads. This breakthrough significantly boosted horsepower, often by over 100 HP, compared to the original cast iron heads.

Goal: Understand the progression of cylinder head technology and its impact on performance and reliability.

Tools and materials

18-Degree Head — Representing a major advancement in valve angle optimization
Early Cast Iron Cylinder Head Chevrolet — Demonstrating the original, fragile head design
Pontiac Small-Block Chevy Head — Illustrating an improved aluminum head design
Ceramic Sealer — Sealing cracks in early cast iron heads during races

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heads were very fragile it was a given they were going to crack in a 500 mile race we actually found some ceramic sealer that we sealed these heads with before we put them on the engine and then race day one of the things the last things the guys had done before the race started they'd pour another bottle of this ceramic sealer and let it circulate because more times than not the head would crack during the race and this sealer would let them finish the race sometimes they could be repaired sometimes not I don't remember how many years we had to run those things but I remember we eat a lot of cast iron dust I bet you were relieved when that changed oh yeah it's just a Pontiac when Pontiac was still involved in racing they're the ones that actually went with where Chevrolet did too they had a bow tie aluminum head but everybody ended up earning the Pontiac head that was made by brodix for Pontiac and much more reliable head a lot easier to work with than the performance was better too but the longevity was outstanding compared to those gas tanks it's heavy too but you can see the difference in the intake runners intake Runners raised up which gives it a straighter shot to the valve in the combustion chamber now what would the power difference from this era to this error be we when we first started with these things and these things evolved over a number of years by changing the Val ain't going by

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