400...big blcok or small block??

[70-boosted]

i have the original 1970 400 block for my 70 formula 400...is that a big block or a small block...cause i heard that the 455 heads fit it...any idea?

 

[Jeff R]

It's not a big block or a small block...it's a Pontiac. If anything it's a "medium block". They're all pretty much the same hunk of metal, just bored differently.

 

[70-boosted]

oh ok good deal...is that why the heads can be interchanged from 400 to 455...so may i ask...if i want to turbo this motor...should i stick with the 6x-8 heads i have now that came with the motor and car...or should i go with a set of 455 heads or something along that...as well...does the blcok i have...being a 2 bolt main, can it handle the big power?

 

[gtojw]

The 6X-8 heads on a 400 gave an advertised compression ratio of 7.6 to 1 if I remember correctly. As for the two bolt block, that will all depend on how hard you plan on boosting it.

With ANY stock block regardless of 2 or 4 bolt mains, one you start hitting that 600+ HP range, you are getting in to dangerous territory in regards to it lasting any length of time.

HTH

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[ED209]

Well It Just A 400

well it the sh#t!!!!! I got one in my 1986 cutlass and it the best damn motor ive ever had.