Cylinder heads are one of the most important parts when it comes to the performance of any vehicle engine. But, it is something about which many people are not adequately informed. Talking about chevy engines, we have three options – 317, 706, and 862 heads. The 317 heads are equipped with superior ports but a lesser horsepower. On the other hand, 706 and 862 heads are almost identical. The similarities between both these heads create confusion even for those who have some knowledge about engine heads.
In this write-up, we will be clearing all your doubts regarding the differences between 706 and 862 heads.
Similarities between 706 and 862 Heads
Before we discuss the differences, let us see what features make both these heads similar to each other. The common features of 862 and 706 heads include:
- Both can be fitted to the same engine blocks
- The valve size for both heads is almost the same
- The size of the port is the same
- The chamber cores are similar
Having these similarities both these engine heads have similar performance. If you are someone who does not bother about minute differences you can pick just any of them. But, if you are someone who notices small performance differences and is very particular about choosing the better option, keep reading.
Differences between 706 and 862 Heads
As discussed already, the 706 and 862 heads are almost similar with minute differences. Let us see what those minute differences are and what impact they have on the overall performance.
Both the heads have almost similar cast but the method of casting differs. While the 862 heads are made using the sand casting method the 706 heads are made using the semi-permanent mold method. Now, you might be wondering how this is relevant to the performance. Well, the SPM method of casting gives 706 a slight edge over 862 in terms of durability.
Due to the different casting methods used in both heads, the finishing smoothness and precision are different. The 706 head has a smoother finish as compared to the 862 head. This makes 706 a slightly better option than 862 head when it comes to efficiency.
The 862 head has a smaller combustion chamber as compared to the 706 engine head. It is due to this difference in the size of the combustion chamber that the compression ratio of 862 is higher. This slightly improves the engine performance and the 862 engine head seem to be standing at a better pedestal as compared to the 706 engine head. But, a downside here is that 862 head can be troublesome in the long run due to issues created by a smaller chamber in the clearance of the valve.
Making a Choice between 706 and 862 Engine Heads
Now that you know the similarities and differences between 706 and 862 heads you are in a better position for making choice between the two. Generally speaking, choices of engine parts are based on three major factors – performance, reliability, and pricing. You can also base your judgment on these three factors and make the right choice for your engine.
You can see a clash between both these heads when it comes to performance. With its smaller combustion chamber, 862 head gives better performance promise. On the other hand, the smooth finishing and precision of the 706 head make it more efficient. So, it will become a really tough choice between the two if you want to make your judgment based solely on performance.
Now, the next criteria for choosing the better one will be based on reliability. Here the choice may seem a little easier. The different casting method used for making the cylinder heads makes 706 head more reliable in long term. Also, the smaller combustion chamber makes 862 lesser reliable in long term. However, you must always remember the difference is minimal.
The price that you will need to pay for these engine heads probably should be the most important determinant for choosing the better option. Whatever differences we have discussed between the two are very minimal or you can even say negligible. So, it would be prudent to check the availability of the two in the market and see at what price you are getting them. If the price is almost the same you can consider the differences discussed above.
The 706 and 862 cylinder heads both are great options to use in a vehicle for good performance. They are mostly similar thus making them an equally good option for an average person. But, some people might like to pick the better among the best. If you want to judge the engine heads based on their performance you can pick 862. And, if you want to go for longevity, durability, and reliability, you might like to pick 706 engine heads.