400 sbc block info needed!

I didnt know where to post this but since the engine is going in a 1970 nova i put it here, i got a 400 small block and i dont know much about them beside they are prone to over heat due to the steam ports, but i know it needs to be bored, i want to go .60 over, what would that make my cubic inches then? isnt .30 over a 406 and .60 be a 409 or so.....i need to know the bore specs for .60 over stock is 4.155, i think, can someone please help me

Because of its thin wall design and siamesed cylinders, a .030 overbore is considered the safe limit on the 400 block. The standard bore is 4.126 so with .030 over (4.156) and the stock stroke of 3.75, the engine would have 406.97 displacement or be considered a 407. The main reason for boring out an engine is to true and square the cylinders. The minuscule amount of additional displacement itself will not make a big difference.

i didnt want to bore it over .60 but if i use this block i have for my project .30 will not clear the cylinders up i knew a few people running .60 over but i knew it would be close to border line on the engines, and thank you for the stock bore measurement i had been looking all night and kept coming up with the one i had so i thought it was stock, any advice anyone can give me about what i need to do about a block?

If the block needs more than a .030 cut, think about getting another block, preferably a 350 that is so much more user friendly. Did a shop diagnose why it needs more than a .030 overbore?

Bob

Another thing you want to watch out for with the 400 SB is that it's externally ballenced on the flywheel and harmionic ballencer. Do not try to run that engine with those parts from other small blocks.

in my opinion .60 over is pushing it, im about to build a 406 which is .30 over, and thats about all i would go

For all the hassles associated with a 400, in the long run you're better off with a 350 especially if you plan on a rebore. Go for a 383/350 based stroker and you'll be happier and have a much more reliable ride overall.

Bob

I didnt know where to post this but since the engine is going in a 1970 nova i put it here, i got a 400 small block and i dont know much about them beside they are prone to over heat due to the steam ports, but i know it needs to be bored, i want to go .60 over, what would that make my cubic inches then? isnt .30 over a 406 and .60 be a 409 or so.....i need to know the bore specs for .60 over stock is 4.155, i think, can someone please help me

I like the 400 smallblock. have always had good luck with the 406. I have never had a problem with either of my 400s. one has factory heads that were redone and it is driven in my fullsize pickup.
My other was in my 73 nova for five years and was race and driven on the street. I have always run a aluminum radiator with duel electric fans which comes with thermostat. I would agree with bob in buying a nice 400 balancer.
Mine has never overheated. I run trick flow heads with 510 lift came, keath black hyper pistons.
I asked the machinist about 60 over and he said not a good idea due to cylinder wall weekness issues. He advised if i was going to do it i fill the block with cement whick only means the dragstrip and no more street.

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