[RocktamusPrim3]

Hey guys, what would you guys think a SBC 400 bored .040 actually is?

I have absolutely no idea on how what to call it, mainly because I'm still new to the innerworkings of cars. Thanks in advance!

[VinceS427bb]

call it a 408...

[Tom Mobley]

still call it a 400 or 406. it's actually close to 408 cu. in.

[novaderrik]

call it a 305..

[Yellomalibu]

Originally Posted by Tom Mobley

still call it a 400 or 406. it's actually close to 408 cu. in.

If I'm talking to a car person, who knows about engines, I'll call mine a 406 - because we all know what a 406 is: a .030 over 400.

If I'm talking to someone who may not know what a "406" is, when they ask what engine I've got under the hood, I usually say "a small block 400", just to keep it simple.

[71454Chevelle]

Kinda of off topic but, on avarage what is the max you can bore a 400 sbc before the walls get too thin? I know to sonic test it but I'm just wondering what is the "norm". This would be for a fairly mild street car.

Sorry for the hijack.

[forcd ind]

i would call it a 409, always fun to add to the confusion, lol

[MrBill66Malibu]

Call it a 400 bored .040 over

[Yellomalibu]

Originally Posted by 71454Chevelle

Kinda of off topic but, on avarage what is the max you can bore a 400 sbc before the walls get too thin? I know to sonic test it but I'm just wondering what is the "norm". This would be for a fairly mild street car.

Sorry for the hijack.

I don't worry about .030 over, but if it needs more, I get it sonic checked first.
Perhaps a machinist or two will chime in and say how far they typically can be safely bored... also, out of curiosity, I'd like to know what the magic number is when they sonic check the cylinder walls - what is the minimum thickness recommended?

[bowtie0069]

Some are junk at only .030" over, while others are fine at .060".
Years ago David Vizard pulled a couple from junkyards and found they would safely go to 4.200", but...

[71-454]

I'd think it is 6th Grade Math....

[Brad Richardson]

Originally Posted by novaderrik

call it a 305..

I'm putting my 307 markers back on but it has a 406 under the hood.