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Post Info TOPIC: How do I know a 350 from a 305?


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How do I know a 350 from a 305?

This is somewhat easy however more times than not I see many people purchase a 305 thinking its a 350.

Here is a few ways that you can know FOR SURE

- Check the casting number on the back left side of the block
- Pull off the heads and measure the cylinder bore, it should be 4 inches

These two methods should help to ensure that no-one pulls a fast one on you. One of the most comon casting numbers for the older Generation One 1969-1979 350's is 3970010.

Feel free to run any casting numbers by me until such time that I have the official list up.



What is to give light must endure burning -- Viktor Frankl




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Yo people,

I've been digging out some ( usefull ) info from way - back about the Small-Block Chevrolet engines etc etc. If your interested in what became what and how, read on !!!

The small-block Chevrolet began life in 1955 and at 265 cubes. Its then modern design and light weight brought about immediate acceptance in the performance world. This engine proved capable of high revs and was great as far as power was concerned. In 1957 the capacity of the 265 was brought up to 283 cubes by over-boring by about 1/8". To accommodate the the bore increase safely, the cylinder wall thickness was increased by a suitable margin. It is possible to bore a 265 to 283 cubes, but porosity can arise. With the introduction of the 283 engine came many performance options, notably for the Corvette. By using standard parts such as the "Duntov" cam and Corvette bits and pieces,the HP of a standard 283 engine would grow from about 170 HP to 290 HP.

1960 saw the introduction of a new head, primarily for the Corvette. This head was commonly known as the "fuel injection" head, and basically had a revised chamber design. This new head boosted the power possible by using factory optional parts up to about 315 HP. In 1962, the small-block underwent another change...The stroke was increased from 3.0", to 3&1/4"...And the bore went up from 3&7/8" up to 4.0". The new displacement gave us 327 cubes.

In 1967 Chevrolet introduced 2 more size variations with their small-block...And the engines in production at this time were the 283,302,327 & 350. The 302 cubed unit ( 5.0ltr ) was very popular for formula 5000 and cetain classes of GT cars and is essentially the 327 block with the 283 crank. It has been thought that this engine ( and probably Fords 302 ) owes its existance to the capacity limit of 5.0ltrs required in many saloon car classes at the time. By 1968, the 283 had been dropped from production, and its place was taken up by an engine of 307 cubes. This engine had the bore size of the 283, but the stroke of the 327...The 350 was the result of a stroke increase 0f 0.230" on the 327 unit. I hope that this info helps out anyone building up an early small-block !




"Only an alert & knowledgeable citizenry can compel the proper meshing of the huge industrial & military machinery of defense with our peaceful methods & goals, so that security & liberty may prosper together".    Dwight D.Eisenhower.

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Posts: 37

Thanks for sharing this. I've always been confused between the two.



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There is a small block inside your car.

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