ok i have been searching/reading this board about the 400 sbc...

anyway, how much boost can a 400 block handle?

can anybody give me numbers for unfilled and filled jackets. this is gonna be going into a street car, and i doubt the engine will ever see over 10 psi of boost.

thanks
andrew

 

mine will (if I can get a D-1sc to blow hard enough) and its not a race block, but I have set a personal 6500 RPM limit on engine RPM. stock "very inspected" block, half filled, splayed caps, deck plugs... I am very curious too, "go or blow" I will know eventually

 

7 psi and short rods to boot. motor is still spinning fine. its the weaker factory 4 bolt block too

 

so as long as i dont go nuts on the boost i really shouldn't have any worry?

 

thats one way of saying it. but a little boost still can also show no mercy if the fuel and timing curves are off, weak fastners, bargain rate pistons,2nd rate head gaskets, poor machining, out of spec. torque wrench-on and on-i guess im meaning that if the motor is getting freshened up-and the parts choosing comes down to cost-usually the better choice is going to be the more expensive of the 2 if longevity is concerned. a little overbuilt and you will never know, a little underbuilt and it will become apparent far too quickly.

 

There is a member of this board who cracked his block running over 15psi of boost on his 400 block. It cracked the cylinder.

I was told the limit of that block is about 650 ft/lbs of torque. And then it starts folding. I dont know with all the prep like shortfill, plugged deck, splayed caps and the like how much it will handle though.

Good luck.

 

so what are the problem areas of 400 blocks??

i know about the cylinder walls....but what are the other problems???

is the 400 basically the same as a regular small block except for the freeze plugs, steam holes, bearing sizes, and bores???

i would have thought that the larger main bearing size would allow for more power output.

 

heres what i know-as far as problem areas (weak points)-factory 4 bolt blocks main webbing is thinner than its 2 bolt brother-get caps and drill for 4 bolt-line bore and use special size rear main seal. short rods suck weewee-too much sidewall scuff-not to mention the ratio and power output potential thats not there.

 

ok, i have two, two bolt block so i am not worried about the webbing.

when i do build this thing up i want to use at least 5.7" rods but i am really looking at 6" rods

any thing else that can be a problem area?