If you take a 400 small block and bore it .30 over you get a 406. Bore .40 and you get a 408, right? Ok, how do you make a 427 out of a 400? I am asking because Im in the process of building a 400 small block for a '69 camaro. My goal is to make the same power and torque as a 502 even if it has to be at a higher RPM. What would you guys reccommend? The 427 has really got me interested. Is this something that can only be done with a performance block? I have a '70 or a '72 400, 2-bolt main.

a 427 would be a stroked 400, a 4 inch throw instead of a 3.75.... .030 over would be a 434.
not sure how much you need to clearance the 400 block. i've only stroked a 350 that did require some moderate grinding.
kip

I'm using a Dart Iron Eagle block for my 434. I really wouldn't suggest using a stock 400 block. The Dart block has .400" spread pan rails on both sides of the block, and it still had to be touched up to clear the rod bolts.

You might want to consider a 3.875" stroke crank. A stock bore will give you 415, and .030" over will get you a 420.

I'm TRYING to put a 30 over 400 with a 3.875 stroke motor together. We've decided to go with an aftermarket block for several reasons but a longer life was the main one. This will be a race only motor and is SUPPOSED to rev to 7500. A street motor with a Chevy block might be OK but the machine work on the block will make the aftermarket block a little easier to swollow even though the aftermarket block will require some work as well. If I am still alive and not completely bankrupt when the motor is finally ready to go, I'll post some numbers.

406CI/500+tq/428hp (http://www.chevyhiperformance.com/techarticles/148_0306_406/)

I am going to comment that to really make a 406 run good is to make sure you have a good set of heads on it b/c I figure my stock big valved -461's just didn't let my 406 breathe properly!!

I always figured like 350hp/425t for my motor..

And my setup pretty much mirrors the engine in the link right down to a Melling torque cam at .480"/230, but on 112 LCA... I did, however use the stock 400 short rods... pdq67