Just when I thought I had my 383 all planned out, my brother-in-law picks up a good 400 block (checked with no cracks) that he says I can have if I want it.

So, which should I build?

I already have a .040 over 4 bolt 350 block and a set of Vortec heads that I was going to use on the 383. The 400 block is a '71 date 4-bolt block and comes with rods and pistons and the stock heads. I will have to pick-up a crank no matter which I decide to go with.

I've read here that the 4-bolt 400 blocks are weak in the webbing and not really that desirable. Are the extra 20 cubes worth the weaker block?

I'm looking for around 400 HP which should'nt really stress a 400 that much.

If I do build the 400, will the vortec heads work for about 400 hp?

would there be any noticeable performance difference between the 400 and the 383?

Sorry for all the questions. I'm leaning toward staying with the 383 but just wanted to get some of your opinions.

Thanks

Dwayne


BTW, what is the actual cubic inches on a .040 over 350 with a 3.75 stroke?

384.6 CI.....b4 you do anything with the 400 block, have it sonic checked. They can be very thin on the thrust side of the cylinder and no use building one that is too thin. The 400 can make more power than the 383...but not with the vortecs. The vortecs will barely work on the 383(for rpms above 5500)they are truck heads after all..made for torque. They are a nice replacement for stock heads but IMO not a performance head