ok heres the deal. i've got a '76 400 sbc and was wanting some opinions on whether i should build it up as a 377(destroked), a 406(.030 over), or a 420(.030 over+3.875 stroke crank), and also list reasons for replies.

 

post this at thirdgen.org too, they usaully have more traffic on the general engine board

 

Build as big as you can afford. I don't know about taking an increasingly hard to find 400 block and destroking it, unless you plan to run high rpm. The cubes of a 406 can be just as quick without buzzing the engine.

 

It all depends on where your going, 400 SBC can't do everything a 350 can. I am building a 406 was going to be a 420 but I can't do it. I want to use 28cc dished pistons cause one day I will be getting a supercharger. a 400 loves 6" rods it gives it great rod to stroke ratio, some say it helps rev up quicker also. But I'm not able to run a 3.875 stroke crank with 6" rods it just won't work piston skirt is to short and will cause rocking. I am however able to run a 3.75 stroke Crank with 6" rods and 28cc Dished Pistons. I have a rotating assembly that I need to get rid of , I don't know the compression but it is out of my 72 400 SBC stock rods aftermarket pistons, stock crank. I have the three center mains also if you don't have them (2 bolt) Make sure your block is clearanced for the crank no matter what crank you use, Make sure your rods are clearanced also. You should use a small base circle cam so that you don't interfere with it and don't forget to drill steam holes in the heads! Check your block before building some 400's had cracks in between the steam holes and the head bolts.. If you have any questions please feel free to contact me. I have been researching this for almost 6 months before I started.. Don't ever wanna have to go back and change anything, just minor rebuilds every tow years or so will be all that is nessecary

Kevin

 

You can make alot of power with any of the combinations. A 420 is too costly and the longevity isn't as good as a 406 or 377. I'm running a 406 with a 150 shot of nitrous.