I have a 400 that was bored .30
Does that mean it has is 6 or 8 ci over. i was told it means 8ci.

 

408.17833....

 

I hope you mean 0.030 instead of 0.30?.....

 

Yeah somewhat ago there was a confution about whether the 0.030" overbore to a 402 made it 406 or 408, The math says its a 408 as mustang 81 said but have you read the popular down and dirty article were a 400 was build cheap to 380 horses, well they state the over 30 got you a 406, but i think its just a miss calculation, you can find the article here:
385 HP Ford 400

 

404page.html

 

stroke = 4"
bore = 4" + 0.030" = 4.030"

cyl. area = (bore/2)^2*pi = 12.7556
cyl. volume = cylinder area * stroke = 12.7556 * 4 = 51.0222

displacement = #cyl * cyl. volume = 8 * 51.0222 = 408.1783

That's all folks.

 

it's only 6, but a 400 is actually a 402 if you do the math.

 

400- 402.123.... cubic Inches

 

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